Prices and profit markers

Bannerlord v1.4.8 · checked 2026-11-10 · updated 2026-11-12

How a town prices an item, how the trade penalty is built, and how the green and red profit markers on the trade screen are chosen, at full precision for game v1.4.8. For a plain-language version, see the trading guide. Trade rumors have their own page: Trade rumors.

No official module (SandBox, StoryMode, NavalDLC, BirthAndDeath) overrides any of the models or behaviors on this page. The numbers in the examples and tables are computed by the Python model in src/bannerlord/trade/.

At a glance

Markers only appear in trade mode (InventoryMode.Trade), not when looting or using a stash.

Market state

Prices are computed by DefaultTradeItemPriceFactorModel. The market state is kept per town and per item category, in an ItemData record with four fields:

• Supply: the town's supply value for the category.
• Demand: the town's demand value for the category.
• InStore: how many items of the category the town holds.
• InStoreValue: the total value of those items, Σ count·value over every item of the category in stock.

A village has no market of its own; it uses its bound town's market.

Base price factor

The base price factor base(cat) is the multiplier a town applies to the value of every item in category cat:

base(cat) = ( Demand / (0.1·Supply + 0.04·InStoreValue + 2) ) ^ p

• Demand, Supply, InStoreValue: the town's market state for cat, defined above.
• p: the exponent. p = 0.3 for animals, p = 0.6 for everything else. The smaller exponent makes animal prices react less to the market.
• Selling: when the player sells, the item's own value is added first, InStoreValue += item.Value, and then the formula is applied. The item being sold already counts as stock.
• Clamp: the result is clamped to [0.1, 10] for trade goods and to [0.8, 1.3] for everything else.

Buy and sell price

buy  price = max(1, ceil (value · base · (1 + penalty)))
sell price = max(1, floor(value · base / (1 + penalty)))

• value: the item's value.
• base: the base price factor of the item's category in this town (with the selling adjustment when selling).
• penalty: the trade penalty below.
• The buy price is rounded up and the sell price rounded down; neither goes below 1.
• When the merchant is a caravan and the client has Silver Tongue, the buy price is multiplied by (1 − SilverTongue.SecondaryBonus).

Trade penalty

penalty comes from GetTradePenalty and is built in this order:

Reading the table:

• The client is the party trading with the merchant; for the player this is the main party. The merchant is the town, village or caravan on the other side.
• The additive rows (+) come first, then the multiplicative rows (×) apply to the running total.
• tier is the equipment's tier. A tier-1 item adds 1.5, each tier above 1 adds 0.25 more: tier 3 adds 2.0, tier 6 adds 2.75.
• TradePenaltyReduction is the reduction the client's Trade skill gives; it divides the penalty by 1 + TradePenaltyReduction.
• ×(1 + Artisan Smith) scales only the equipment term (1.5 + 0.25·max(0, tier − 1)), not the running total.
• With no client party and no item-type terms the penalty is 0.06·0.2 = 0.012. For other items the item-type terms are added to 0.06 first, and the whole sum is then ×0.2. This is the penalty trade rumors are recorded with (see Trade rumors).

Example: the plain penalty

The main party buys or sells trade goods in a town, at peace, with no Trade skill reduction and no perks. Only the start row applies, so penalty = 0.06. This is the penalty used for the price curve below.

Example: selling tier-3 equipment

The main party sells a tier-3 item of value 1000 in a town, at peace, with no Trade skill reduction and no perks, where base = 1.0.

1. Start: penalty = 0.06.
2. Selling equipment, not a caravan: + (1.5 + 0.25·max(0, 3 − 1)) = + (1.5 + 0.5) = + 2.0, so penalty = 2.06.
3. No other row applies; the client-party row divides by 1 + 0 = 1.
4. Sell price: max(1, floor(1000 · 1.0 / (1 + 2.06))) = floor(1000 / 3.06) = floor(326.80) = 326.

The item sells for 326, about a third of its value.

Example: a caravan client at war

A caravan client at war with the merchant's faction, trading goods in a town, with no Trade skill reduction and no perks: (0.06 + 0.5) · 0.5 = 0.28. The equipment and pack-animal rows do not apply to a caravan client.

Price curve example

A trade good of value 40 in a town with Supply = 50 and Demand = 20, traded by the main party with penalty = 0.06, for stock values from 0 to 2000.

A trade good worth 40 with supply 50 and demand 20.

Step by step for the row with InStoreValue = 300, p = 0.6 (a trade good):

1. Buying: Demand / (0.1·50 + 0.04·300 + 2) = 20 / (5 + 12 + 2) = 20 / 19 = 1.0526.
2. base = 1.0526 ^ 0.6 = 1.0313, inside the trade-good clamp [0.1, 10].
3. Buy price: ceil(40 · 1.0313 · 1.06) = ceil(43.73) = 44.
4. Selling: InStoreValue becomes 300 + 40 = 340, so 20 / (5 + 13.6 + 2) = 20 / 20.6 = 0.9709.
5. base = 0.9709 ^ 0.6 = 0.9824.
6. Sell price: floor(40 · 0.9824 / 1.06) = floor(37.07) = 37.

The same steps for InStoreValue = 0 give base = (20 / 7) ^ 0.6 = 1.8774 and a buy price of ceil(79.60) = 80; selling, base = (20 / 8.6) ^ 0.6 = 1.6593 and a sell price of floor(62.61) = 62.

Profit markers

The marker is chosen by SPItemVM.UpdateProfitType, which calls GetProfitTypeFromDiff(a, b). There are five states, ProfitTypes:

a and b are two prices whose meaning depends on the marker mode (below). The checks run in this order and the first match wins:

GetProfitTypeFromDiff(a, b):
  a == 0          -> Default
  a < 0.80·b      -> HighProfit
  a < 0.95·b      -> Profit
  a > 1.05·b      -> Loss
  a > 1.20·b      -> HighLoss      (unreachable: the 1.05 check returns first)
  else            -> Default

The HighLoss bug

HighLoss is never shown: any loss beyond 5% displays as plain Loss. Any a > 1.20·b also satisfies a > 1.05·b, and that check comes first and returns Loss. In the example table below, a paid price of 60 against a sell price of 44 (ratio 1.36) shows the same red as 50 (ratio 1.14).

Your inventory (Appraiser or Whole Seller)

• a = your average purchase price for the item.
• b = the sell price in this town (ItemCost).

TradeSkillCampaignBehavior keeps one running average per ItemObject, for items without a modifier only. avg is the average price paid and count the number of items it covers:

buy n at total cost C:   avg = (avg·count + C) / (count + n);  count += n
sell k:                  count -= min(count, k); entry removed at count 0
outside trade mode:      count is capped at what the party still holds; entry removed if none left

Selling lowers count but leaves avg unchanged.

Items never bought (looted, crafted, rewards) and items with a modifier (e.g. "Fine", "Rusty") have a = 0 or a = b and always show Default.

So: green = selling here earns ≥ 5% (≥ 20% for the strong marker) over what you paid; red = selling here loses > 5%.

Merchant inventory (Caravan Master or Market Dealer)

• a = this town's base(cat).
• b = the mean base(cat) over every other town in the world, computed when the trade screen opens (InventoryLogic.InitializeCategoryAverages).

Both sides use base only: no trade penalty, no perks, no stock change from the item itself. Green = this category is ≥ 5% (≥ 20%) cheaper here than the world average; red = > 5% dearer. Per category, not per item, and it includes towns you have never visited.

Marker examples

Your-inventory rows compare a paid price with a sell price of 44; merchant rows compare a local base with a world average of 1.

Marker colors for goods you bought (compared with the price here) and for towns (compared with the world average).

Step by step for "Paid 40":

1. a = 40, b = 44. a is not 0.
2. 0.80·b = 35.2; 40 is not below it, so not HighProfit.
3. 0.95·b = 41.8; 40 is below it, so Profit (green).

Step by step for "Paid 60":

1. a = 60, b = 44.
2. 0.80·b = 35.2 and 0.95·b = 41.8; 60 is below neither.
3. 1.05·b = 46.2; 60 is above it, so Loss (red). The 1.20·b = 52.8 check that would give HighLoss is never reached.

Game code

IL for every method on this page, decoded from game v1.4.8:

• DefaultTradeItemPriceFactorModel.il: GetBasePriceFactor, GetPriceFactor, GetPrice, GetTradePenalty.
• DefaultPartyTradeModel.il: GetTradePenaltyFactor (Trade skill reduction).
• TownMarketData.il and ItemData.il: market state per town and category.
• Town.il: GetItemPrice, GetItemCategoryPriceIndex.
• TradeCampaignBehavior.il: market initialisation and daily market updates.
• InventoryLogic.il and InventoryLogic.averages.il: item prices on the trade screen, InitializeCategoryAverages.
• InventoryTradeVM.avg.il: GetAveragePrice.
• TradeSkillCampaignBehavior.il and ItemTradeData.il: the running purchase average.
• DefaultPerks.InitializeAll.il: perk skill thresholds and bonuses.

Reproducing

The IL was extracted with the steps in How the findings were reversed:

1. Snapshot the DLLs into dll/v<ver>/: uv run python -m scripts.reversing.sync_dlls.
2. Dump a type's members: rea inspect-managed-members dll/v1.4.8/<asm>.dll --type <Full.Type.Name> --format json --full-output > ev/<T>.json.
3. Decode the method bodies: python3 scripts/reversing/ildump.py ev/<T>.json dll/v1.4.8/<asm>.dll '<regex on Type::method>'.

Changelog

• v1.4.8 (2026-11-10): First version from IL.