Money Results

A while back I initiated a discussion on money in D&D, and created a poll with a couple options for a preferred money system. You can see the results at the top here, which I'll be using in my own games starting today. One of the things that was pointed out last time was that the by-the-book OD&D money structure of 1:10:50 (gold:silver:copper) was passingly similar to the real-world coin values in medieval England of about 1:20:80. Note again that this is separate from the often-confused issue of "moneys of account", i.e., pounds/shillings/pence at 1:20:240, which were used for bookkeeping purposes only, and not actually coins. We consider it a mistake to use those ratios in AD&D for several reasons. (And thanks to commenter Tsojcanth for pointing out that GURPS also uses the historical 1:20:80 coin conversion rate.) Our OD&D coins more-or-less match the English silver "Groat" (4 pence, 1/3 of a shilling) and gold "Half Noble" (40 pence, 1/6 of a pound value). So here's what I'll be doing from now on:
  1. Convert the economy to a "silver standard". Read the OD&D Basic Equipment list as being priced in silver pieces, not gold (and start PCs with the same). Likewise, read the values for gems, jewelry, hiring henchmen, paying specialists, tolls and tithes, crafting magic items, etc., as being in silver pieces. Award experience at the rate of 1 XP = 1 sp.
  2. Reduce coin treasures appropriately. Fortunately, by choosing the OD&D conversion rate of 1 gp = 10 sp, it's simple to convert monetary treasures to an equivalent purchasing amount; just divide by 10. For example, monster treasure-types (Vol-2, p. 22) are now generated in 100's of coins, not 1000's. Do the same thing for other coin-specific tables, treasure troves in pre-published adventures, etc.
  3. Change the encumbrance rate of coins. Let's assume that our money weighs an average of 100 grains per coin. This is realistically large: 6.48 grams per coin, 70 coins per pound, and 980 coins per stone weight. For simplicity, we'll say: 1,000 coins per stone in our streamlined encumbrance system. That makes it exceedingly easy to adjudicate. (Another benefit to the 1:10 gp:sp choice is that it accurately reflects the medieval value of gold & silver by weight, i.e., it's correct to think that our coins do in fact weigh the same amount.)
  4. Use historical pricing data to fill in gaps. Now that we have a more real-world based economy structure, it's reasonable to use historical resources like the Medieval Sourcebook to answer more esoteric questions when they come up in play. You'll just have to convert moneys-of-account to coinage: Where it says pence (d) use the same number of copper coins; where it says shillings (s), multiply by 3 for our silver coins; and where it says pounds (L), multiply by 6 for our gold coins.
Examples of treasure generation: We'll use the (unguarded) treasure table on Vol-3 p. 7. On the 1st level, I roll up: 30 sp and 3 gp (a little under average). That may look very small to our jaded eyes, but notice that it's enough to buy a full suit of plate mail and a sword. If you want somewhat more exciting treasure, advance the game to 4th level: Here I get 500 sp and a +1 sword. Later at the 10th level: A treasure with 3,000 sp, 1,000 gp, and 7 gems worth base 50 sp each. Note that this entire treasure can be carried away by one character in a big, normal sack (4 stone weight), earning 13,350 XP (over 1/10th of a Lord's level), and enabling him or her to purchase a small galley. Now that's treasure worth fighting for! Some of the lessons here, I think, are these: You don't want to "blow your wad" with enormous summer-action-movie-size treasures right at 1st level. A fat purse with a few dozen coins should be worth a thief's time to knife someone over. A wizard should be able to carry enough money in the folds of his robe to buy a night's stay at an inn, hire a lantern-bearer, or procure some interesting ephemera. If you want to jump into "heroic" adventure from the get-go, then it should match the rest of the D&D mechanics in that 3rd or 4th level is where you would start. Pricing power, and therefore game-balance, is always exactly the same as in the regular game; a roll of N on whatever treasure table allows you to buy exactly the same number of helmets or horses (or whatever), and awards exactly the same XP, as in the base game. The one thing that's changed is carrying capacity -- characters can pack out almost ×100 greater value in treasure (×10 for the silver-standard switch, and ×7 for the weight-of-coins change). No longer do you have characters leaving the majority of a treasure in the dungeon at 1st level, and worsening geometrically from there. Examples of historical conversions: Look to the Medieval Sourcebook. Leather armor in 1285 is listed as 5s (shillings): convert to coins by 5×3 = 15 silver pieces (historical groats), and notice that's identical to the OD&D equipment list. Helmets (Burgonet, 1590) were 4s: convert 4×3 = 12 silver pieces; compare to OD&D listing of 10. Draft horses (13th cen) are documented at 10s-20s: convert starting price 10×3 = 30 silver pieces; again, identical to the OD&D listing. Lessons from this exercise: The OD&D price listings are actually somewhat realistic (at least on the right order-of-magnitude; usually within a factor of ×2 or ×3 or so) if you read them in units of silver pieces, like the historical "groat" coins. (But not gold pieces; nor shillings or any other non-coin money-of-account.) I think that's good news, because it allows us to leverage our wealth of resources from history to support and enrich our game in this particular context. Now I'll point out a pair of outliers. One exception to realistic OD&D pricing in silver coins is the heavy armor types, chain and plate mail. While Vol-1 lists these at prices of 30 and 50 respectively, looking at the Medieval Sourcebook shows that they could realistically be valued at 10 times those figures in silver pieces. You could change them, but I'm conservative enough that I don't want to re-do the pricing list just for this. I'll be giving my players the price list unchanged from the OD&D books, merely referencing them in terms of silver instead of gold pieces, and running the game unchanged in that regard. The other exception is the cost of men-at-arms. One thing that's apparent in OD&D as you look on facing pages in the DM's book (Vol-3, p. 22-23) is that the prices for Specialists & Men-at-Arms are in totally different magnitudes (the former in hundreds or thousands per month; the latter in ones or maybe tens per month). The costs for Specialists can be interpreted as silver/month and be compatible with the rest of our system, as usual (compare to Sourcebook: "armorers"). However, if we take the Sourcebook mercenary/army wages (usually in a few pence or shillings per day), add in a like factor for upkeep/support, multiply out to monthly payments, and then convert to our half-noble gold coins, then we get numbers very similar to the OD&D table. So this is the one case in our entire system where we should do the following for realism's sake: Read the OD&D Men-at-Arms monthly costs in actual gold pieces, not silver pieces (i.e., multiply by 10 for silver pieces). One other note: If you'd prefer to use the 1:20:80 ratio in your own game, almost all of the foregoing would still apply, although you'd have to divide coin treasures by 20 (instead of 10). When converting historical prices you'd multiply both shillings & pounds by 3 to get your silver and gold coinage. And OD&D men-at-arms prices could possibly be cut in half (reading in gold pieces). In summary, this fairly lightweight revision provides a lot of advantages: (1) We maintain by-the-book coin conversions for OD&D. (2) We can still use almost all of the OD&D tables and figures as written, simply dividing coin treasure amounts by 10 on the fly. (3) Game balance is maintained with identical overall purchasing power and XP awards. (4) We create a campaign where PCs can carry appreciably large amounts of value with them, whether in the dungeon, wilderness, or city (even when treasures are increasing hugely at the upper levels). And (5) We develop an economy and coinage reasonably in tune with medieval Europe, such that we can use historical sources to enrich and reinforce our game when desired.


  1. The article on the silver standard in D&D that I wish I'd written. Good stuff.

    "Money is silver; treasure be gold."

  2. That's some good scholarship and adaptation. AD&D armor prices seemed to be more in turn with reality, though, and they give characters something to work up towards.

    For my own uses, ease of use trumps everything. So while I loved silver standard ever since I first saw it in Runequest, I prefer to go up and down by factors of 10. You can still use medieval prices by keeping the silver standard, but adjusting copper accordingly.

  3. Very good article. I wish too I've written that.

    Anyway, about castles:
    the tower listed for 395L converts to about 284000 sp, which is 10x off with respect to the expert cost for the "fat" round tower (listed at 30000 old GPs).

    Tattershall looks to me as the expert set square keep, but we can't say what the 450L/year were spent for (as a college is mentioned).
    450L * 240 * 3 * 13 = about 4.2 MILLION sp. The square keep is listed as 75000 old gp... anyway, Lord Cromwell decided to go posh and use bricks instead of (abundant) stone. Go figure.

    Anyway, if i welcome the 10x rate for metal armours, the same rate for fortifications means that my campaign won't see many new castles. Which I don't like.

    A couple of bits:
    Archer's wage 3d/day = 3*3 sp/day = 9 sp/day. It's listed at 5gp/month in the expert set.

    It's significant that "Mounted archers, armored infantry, hobilars, vintenars" are ALL at 6d/day (18 sp/day) while in the expert set are listed at 15, 2 or 3, 10 gp/month, while vintenars (I'd say some kind of corporal or sergeant) are not listed (which is odd). The expert sets mention as well to double pay on wartime. Furthermore it's kinda obvious that the room and board are to be paid by the employer, and we don't know if the medieval sourcebook accouunts for it or not.

  4. Tsojcanth: That's good to think about, you're ahead of me in digging into the effects of those building costs. However, I'm coming up with very different multipliers than you are -- e.g., to convert pounds-to-new-sp, I'd just multiply by 60 (L x6 gp/L x10 sp/gp), so I'm not sure where your 240 * 3 comes from? Which of us do you think is mistaken?

    Some examples the way I'd do it from the Medieval Sourcebook:
    (1) Merchant's house, L33. Convert 33 x 60 = 1980 sp ~ 2,000 sp. OD&D Vol. 3 lists a house like this at 2,500.
    (2) Stone gatehouse, L30 (est.) Convert 30 x 60 = 1,800. Vol-3 lists same at 3,000.
    (3) Tower in wall, L333. Convert 333 x 60 = 19,980 ~ 20,000 sp. Vol-3 lists big round tower at 10,000.
    (4) Tattershall castle, note this includes adjacent college, so I'll cut in half as a guess for castle keep alone? I get 450 x 13 x 1/2 x 60 = 175,500 sp. Vol-3 lists Great Keep at 72,000 total.

    Analysis -- Again, all of these numbers are in the same order-of-magnitude, varies by between about half to double. (Which gladdens me greatly.)

    For men-at-arms like archers, my assumption is that while OD&D/Expert includes support/upkeep, Sourcebook literally lists only "wages" (I suppose we could dig into original source material to be sure). As a guess I just double wages to find total with upkeep (or you can calculate food for men & horses, comes out about the same).

    So for archers: 3d/day x 2 = 6d/day with upkeep. Convert 6d/day x 1/5 sp/d x 1/10 gp/sp x 30 days/month = 3.6 new-gp/month. Compare to Vol-3 listing of 5 gp/month (same as copied into your Expert book), note it's about the same.

  5. Delta: i lost my reply, and I'm at work. anyway, the 240x comes from the Lsd ratio (from the medieval sourcebook) and the 3x from your analysis. more later, I hope :)

  6. Delta: I got the conversion rates wrong. Totally my fault for being up commenting so stupidly late and writing BS here.

    Anyway, your math is right, mine was wrong. I might unleash the new coinage system to my players this weekend (maybe together with your stone encumbrance system).

  7. I had read those articles assuming they were talking about weight in pennies for the gold coins not value. For the ½ noble, 40 pence weight, which would be about 2 2/3 ounces. About the size of a casino chip. Now that I re-read they are talking about value, not weight; much smaller gold coins than I was imagining.

    The (1/60 lb) Groat would be a little bigger than a US silver quarter, but the gold is twice as dense and would be half as big, about a big as 2 US Dimes; smaller than a US dime if the gold to silver exchange rate was 20:1.

    Much easier system than I was imagining with farthings, silver pennies and casino sized gold coins worth 600-1200d (had not pegged if I should 30, 40 or 60 pence weight gold coins)

  8. Thank you for your answer in the other post. I've read through everything on this site, and I still have a few questions:
    1) First, have you updated the post with reference to the error in calculations discovered?
    2) I've used 1 D&D silver piece = 1 "new" silver penny for my system. Is this the way you intended? I've been a bit back and forth about it, and came to the conclusion that to have 1 GP = 1 sp would cause all the low cost stuff, such as gate pass, customs, travel per mile etc. , to most likely be free of charge (due to the lack of coins to pay with).

    I love your writing — so thanks for taking the time.

  9. Hey CM, thanks for the interest!
    (1) I think everyone else agreed there weren't any calculation errors -- what were you thinking of specifically?
    (2) Well, the main way I think about it is to interpret 1 D&D silver piece as 1 sterling silver English Groat (4 pence), etc., to just re-value all prices as being in these silver pieces (not gold), and to divide all coin treasure by 10.

    My attitude is that the coins actually remain the same, but all the prices of objects change (in units). Does that make sense?

  10. Hello again, and my apologies for not following up till now.

    After lots of thinking hither and thither, and after completing the subject "History-1012: A medieval monk's tales: Jocelin of Brakelond describes a dangerous world" I've actually ended up opting for a system using the following monetary units (with the norwegian terms in brackets and abbr. forms i square brackets):
    1 gold crown (gullkrone) [GC/GK] = 20 gold pence (gullpenninger) [gp]
    1 gold penny (gullpenning) = 12 silver pence (sølvpenninger) [sp]
    1 silver penny (sølvpenning) = 4 copper farthings (kobberøre) [cf/kø]
    1 silver mark (sølvmark) [SM] = ⅔ GC id est 3 SM = 2 GC = 13 gp 4 sp.
    This is in other words a copy of the medieval 1:20:240-system used , and according to my history professor, gold coins were used from time to time, but didn't seem to get a foothold again (after the Romans) till quite late.
    I've chosen to not change the price lists from my core books (we play 3.5), so 1 D&D silver piece = 1 silver penny. This makes price conversions mostly straightforward, however, XP awards are now 1 XP = 10 sp, since the gold coins are a rare sight.
    This did, however, post some problems. During the earlier middle ages, only the silver piece was actually minted, so one of the questions I had for my professor, was how they then dealt with low priced items, such as buying an ale at the local pub. The answer was as simple as it could be: they had credit, so when it equalled a silver penny, they payed. To avoid this problem (more things to keep a record of for me), I decided that the silver pence in my campaign, are riveted, so that they can easily be split in halves or quarters. In addition, the copper piece is used, but mostly by lower class people, and only for very low priced items. The copper piece is also riveted, but only one way (i.e. halves), and this half-copper is usually only used for toll in towns that demand a ½-cf in toll regardless of whether or not you are entering with any goods. To convert the D&D cp to 4/sp copper farthing, I used the following guideline:
    1–2 cp = 1 cf
    3–5 cp = 2 cf
    6–7 cp = 3 cf
    8–9 cp = 4 cf

    What was my motivation for using this system?
    First of all, as Chris said: "Money is silver; treasure be gold." I really wanted the gold coins to be rare, and when you actually had one, you'd be a lucky man. Only those dealing in expensive items such as jewellery, or buying large quantities or huge items such as houses and ships, ever use gold coins. Also, the aristocracy and high ranked guild members naturally prefer these coins. Thus, this is the coins' order of appearance: sp, cf, gp, GC & SM.
    Secondly: I wanted to get a more historically correct feel to my campaign.

    I'm sorry for this ridiculously long answer – it happens. As to my and your number 1), I don't remember. I was probably mistaken.

  11. Mistake made:
    1 silver mark (sølvmark) [SM] = ⅔ GC id est 3 SM = 2 GC = 13 gp 4 sp.

    1 silver mark (sølvmark) [SM] = ⅔ GC = 13 gp 4 sp id est 3 SM = 2 GC.

  12. Am I mistaken in assuming you've based your economy on late medieval era? As you might be aware of, during the 1200's there was a massive inflasion, so all of a sudden the usual one-p a day for an untrained worker couldn't buy the same as a few years back.
    Around 1300, a labourer would earn a maximum of £2 a year. During the 1270's, a thatcher's mate would earn (roughly) 1d a day. In 1351 a master mason would earn 4d a day = 1 groat (correct?). [Sidenote: all prices are from The Medieval Sourcebook's price list.]

    So I understand your economy as being based on the later medieval period, whereas I have chosen to base it on earlier medieval times (roughly around the latter part of Jocelin of Brakelond's life and chronicle).

    Does that make sense?

  13. Hey CM -- You're right, I mostly look at prices of things around the 1300's. (I could make an argument with several data points that regular D&D is set around that time or later: consider armor types, ship types available, etc.)

    I must admit that I'm confused by your system's terminology. What I'm used to is that "pence" is a fixed unit of value; "penny" is a coin type with that value; and neither could change by making them out of a different material. (So "gold penny vs. silver penny" gets my eyes crossed.)

    I might go back to my claim on the Primary House Rules page: "Shillings and pounds were not coins!"

    Let's say I propose this collegial challenge -- Ask your professor (if he's still available to you): "Did anyone ever make a coin worth 240 pence (of any metal type)?" My understanding is that the answer to that would be "no".

    So that might illuminate the issues involved; which is to say, the 240-unit was for counting only, not for coins.

  14. Follow-up to CM: 1st, I see there was indeed a coin called the "gold penny" in England -- minted 1257; worth 20 pence; was not popular; discontinued within about 10 years.


    And my comment "Shillings and pounds were not coins!" deserves this footnote: In the ancient and middle-ages period. The first 1-pound coin was minted in 1489 with the gold Sovereign.

    "The First One Pound Coin: The gold sovereign came into existence in 1489 under King Henry VII...
    The pound sterling had been a unit of account for centuries, as had the mark. Now for the first time a coin denomination was issued with a value of one pound sterling."


  15. Hello, again, and I’m so sorry for not checking back to this post for a year!

    As to your answer:
    You are of course absolutely right: the period I’ve based my monetary system on din’t have any coins besides the silver penny (I asked my professor). The way I’ve thought about it is slightly mixed-up, though I’m aware of it, and my player’s are too. I use major elements from the 13th century, and shove this into a more or less regular D&D-world (14th to early 15th century, if I’m not mistaken).

    What I wrote was slightly inaccurately expressed: I chose to base my monetary system on the book-keeping system used, for two reasons: simplicity when checking historical sources, and to get a really high-valued gold coin. Since the last time I wrote to you, I’ve more or less discontinued the gold penny (it is considered a rich-people-who’d-like-to-show-off-coin) for a silver crown instead.
    My goal was all the time to get rid of two problems with D&D’s standard monetary system: The size and weight of the coins, and the players’ disregard of anything not gold. The system worked, so I’m happy.

    However, I do have another problem I’ve seen surface: the monetary system in standard D&D is seriously flawed! The wages shown in the hireling-lists do not match what an artisan can actually earn using his profession check. Furthermore, the prices for anything but common items are insanely high; a commoner can probably never, without getting seriously lucky, hope to even lay his hands on a simple sword (even a shortsword) when it costs 10 GP = 100 SP; the Mediaeval pricing for a cheap sword was a meager 6d… (Medieval Sourcebook)

    Do you have any thoughts on this? If getting the economy in D&D to actually make sense, it seems to me the entire system needs a revamp. I wrote a post on it a couple of days ago, if you’re interested, though I have to warn you it is probably not as well-thought-out as yours. http://mrsadventurer.blogspot.com/2012/02/problems-with-economic-system-in-d.html

  16. ^ Hey, Tor-Ivar -- Thanks for checking back in (now here I've gone a half-month before replying). I think that's really interesting that you've continued to think about your system and refine it over the last year, and pay close attention to how your players interact with it. I think that's great.

    I agree that the main thing in core D&D is that the items and the wages are just totally out-of-sync. I think the men-at-arms level wages are about right, and everything else in the game is inflated an order of magnitude (because of the initial arbitrary calling of "gold pieces"). So actually what I do is keep men-at-arms wages as written, and just declare everything else in the game to be really "silver pieces" (i.e., divide by about 10 in value). That's a pretty easy fix, and I find that it more-or-less works out when I check it (a heck of a lot more than the original published system).

  17. This comment has been removed by the author.

  18. hanks a lot for your answer, and no need to apologize – you’ve been sick! I assume you set 1 XP = 1 sp when dividing by ten. Do you know of any attempts to make a economic system for D&D that actually works? By that, I mean something that looks at real-life values, and then includes magic in this as a regular craft/profession (though high-priced). I’ve been thinking of trying to re-vamp the whole thing for a different campaign I’ve been mind-meddling with. Should I decide it simply is too much work, I’ll definately go for your system.

    By the way, here’s a pricelist I made for my campaign (GK = gullkrone = gold crown, SK = sølvkrone = silver crown, kø = kobberøre = copper farthing; the rest should be self explanatory), in case anyone might’d be interested. Its three columns in Norwegian is the name of the items in Norwegian, the largest coins the item can be paid with, and the silver-only-based payment.

  19. Hey, that list looks really nice, excellent work! THe last I heard, the guys making the Adventurer-Conquerer-King System (ACKS) were carefully considering the money/economic system (pretty similar to how we're thinking about it here). You might check that out for more (search "economy" and check the links that follow):


  20. I realize you're working pretty fast and loose with this system, but I think choosing the groat as the basis is odd. It was the five dollar bill of its day - one would no more count a cost in groats in 14C England than we would count a cost in five dollar bills.

    It was also a lot of money - probably about 2 days wages for a labourer, or a day for a tradesman. Would it not make more sense to peg the basis of the system on the penny, which was both the basis of specie and the basis of the money of account? There were two smaller coins than the penny, the halfpenny and the farthing, which could stand in for your sp and cp (with the penny standing in for the gp).

    This would match up better with how medieval people would really see money, simplify importing prices (as you will always find prices listed as pounds, shillings, and pence (or occasionally marks, shillings, and pence), and mean that you're trucking about 1/4 the weight of metal to pay for something.

    Some thoughts regarding comparing prices from different eras and countries, the sterling is probably the best medieval silver standard you could use (its weight, fineness, and value varied very little over time), but it did still vary, trending to be worth less over time. If you're finding French prices in livres tournois or livres parisien, it's a highly fraught exercise. The livre tournois went through dozens of debasements, revaluations, etc in the 14th C alone. Spufford's Handbook of Medieval Exchange is the go-to reference for this stuff.

    Anyway, I guess all of this is to say that to my mind it makes more sense to use the penny as the basis of the system, giving you something more like .25:.5:1:4:36 (or 1:2:4:16:144)- more in line with the medieval English farthing, halfpenny, penny, groat, and the florin (which was worth about 3 shillings and was a common gold coin across all of Europe).

    Another flavourful silver standard practice that's maybe worth considering adopting is the mark. It's not certain, but it definitely seems that ingots of silver weighing/worth one mark and stamped to prove their worth were used instead of carrying around masses of coins when traveling, especially before the widespread introduction of bills of exchange and/or if travelling somewhere you couldn't get a bill of exchange for.

    Thanks for indulging my ramblings!

    1. Thanks for reading and the thoughtful reply. The main point I'd diverge at would be that I'm not trying to define a money of account. Rather, we're dealing with concrete coinage: something we can describe as the D&D adventurer physically carrying and paying over. The assumption being that when one says in-game "I slip a gold piece in the slot" that this is speaks of a well-defined single object, not an accounting statement that could be ambiguously fulfilled with either 80 pennies or 20 groats or 1 noble or whatever.

      Likewise, the penny is not bad for a new system from scratch (Gygax did that in DJ), but again I'm trying to regress something that has the smallest error from D&D game equipment prices. Usually my go-to is the Medieval Sourcebook: Prices (link.

      At the risk of repeating myself, I'll grab two examples: war horses in 12th c. and draft horses in 13th. (listed at 50s and 10-20s, mean 15s). If we convert to groats we get 150 coins and 45 coins respectively. If we convert to pennies we get 600 and 180 coins instead. Looking at OD&D costs, listed at 100/200 (light/heavy) and 30 respectively, we see the former (groats) is a better match. That's just two examples, but as you can see in the other posts, I see that regression happen again and again in more other D&D subsystems.

    2. I've run into some people who will in fact claim that "1 gold piece" is a money of account representing multiple coins, but I simply don't find that either helpful for interpreting/narrating the game or liguistically coherent.

  21. Thread necromancy: what does this do for prices already listed in sp and cp where gold is the standard piece? Do the values increase by a multiple as well?

    1. Thanks for question. A: Looking at OD&D, there aren't any. Everything is in the single unit of gp.

  22. If the value of a silver piece "increases" by 10, such that a 3gp dagger is now 3sp, how is copper's value affected, i.e., if a mug of ale costs 2cp under the old system, how much does it cost under 1gp=10sp=50cp, where 1sp now buys what 1gp does?

    1. As noted above, in OD&D, there aren't any items with list prices below 1 gp. Personally for inn/tavern individual stuff I just handwave it as included in the monthly upkeep costs. (But: Buying a round of drinks for info is 10-60 as per OD&D Vol-3.)

      If someone forced me to price something like that, I'd look up the Medieval Sourcebook and convert. E.g., It lists a quart of good beer (16th c.) at 1d (pence). If we carefully convert it we'd do 1d × 1s/12d × 3sp/s × 5cp/sp = 1.25 cp, round to 1 cp. In short: a real-world pence converts to 1 cp (penny).

      But even shorter: Among reasons I like OD&D is that there aren't any costs like that, there's just one single unit in the price tables.