CS2 trade-up contract: the 10-skin math, the float formula, and the knife rule the wikis disagree on
Posted: Wed Oct 21, 2026 4:37 pm
CS2 trade-up contract: the 10-skin math, the float formula, and the knife rule the wikis disagree on
Quick summary
Open the contract from your inventory and select ten skins of the same weapon grade. You get back one skin one grade higher, chosen randomly from the higher-rarity skins of the collections those ten came from. [1][2]
The ladder runs Consumer Grade to Industrial, Industrial to Mil-Spec, Mil-Spec to Restricted, Restricted to Classified, and Classified to Covert. [1]
Collections decide the odds. You can mix skins from different collections as long as the grade matches, and the more you pull from one collection, the more likely the output comes from it. Nine skins from collection A and one from collection B gives you roughly a 90 percent chance of a collection A output. [1][2]
The Fandom wiki records that the contract used to be called the Arms Deal Contract and was renamed with the Operation Bravo update, which is also when it stopped being limited to a single collection. [2]
The float formula
The wear on the outcome skin is not random. Both wikis give the same calculation: [1][2]
f = x * (y - z) + z
f is the float of the outcome skin. x is the average float of the ten inputs. y and z are the maximum and minimum float caps of the skin you actually receive. [1][2]
The wiki's worked example: ten inputs averaging 0.10 into an output with a 0.00 to 0.50 range gives 0.10 * (0.50 - 0.00) + 0.00 = 0.05, which lands in Factory New. [1]
That is the whole reason people sort inputs by float. Cheap skins that have drifted up in wear drag the average with them, and the outcome lands in a worse wear band than the one you were aiming at.
StatTrak and what you cannot use
Ten StatTrak inputs produce a StatTrak output. Mix StatTrak and normal inputs and the output is normal, so the two categories never mix in one contract. [1][2]
Three kinds of skin are excluded as inputs. Knives and gloves cannot be used. Contraband skins cannot be used. And a skin that is the top grade of its own collection cannot be used, because there is nothing above it to trade into. The Fandom wiki's example is the Tec-9 Ossified, which is Mil-Spec but sits at the top of the Aztec Collection. [2]
Consumer Grade skins are not a possible outcome either. [2]
The knife rule, where the sources disagree
Counter-Strike Wiki says you cannot trade up to knife or glove rarity, and lists Extraordinary and Gold as out of reach. [1]
The Fandom Counter-Strike Wiki says the opposite, and puts a date on it. Following the October 22, 2025 update, five Covert skins can be traded up for one knife or one pair of gloves from a collection represented in the inputs, and five StatTrak Covert skins can produce one StatTrak knife. [2]
Valve's official update notes do not mention trade-up rules, so I cannot settle this from a primary source. [3] The contract screen in your own inventory is the only place the answer is authoritative, and it is worth checking before you commit five Covert skins to a knife attempt.
Is it worth doing
The contract is one-way. The ten inputs are destroyed. [1]
It pays when the expected value of every skin you could receive is higher than what you paid for the ten inputs. That needs current market prices for the whole possible output pool, not just the skin you want. The wiki lists three conditions: expected value above input cost, collections loaded with the valuable skins you are targeting, and the float formula keeping the wear where you want it. [1]
Rounding in the float calculation can also produce results you did not expect, so a near-miss in the math is not a near-miss in the outcome. [1]
FAQ
Quick summary
- The contract takes ten weapon skins of one rarity and returns one skin of the next rarity up, pulled from the collections you fed it.
- The wear on the returned skin is calculated, not rolled. Both wikis publish the same formula.
- StatTrak carries over only if all ten inputs are StatTrak.
- The two main wikis disagree on one point: whether you can trade up into a knife or gloves.
Open the contract from your inventory and select ten skins of the same weapon grade. You get back one skin one grade higher, chosen randomly from the higher-rarity skins of the collections those ten came from. [1][2]
The ladder runs Consumer Grade to Industrial, Industrial to Mil-Spec, Mil-Spec to Restricted, Restricted to Classified, and Classified to Covert. [1]
Collections decide the odds. You can mix skins from different collections as long as the grade matches, and the more you pull from one collection, the more likely the output comes from it. Nine skins from collection A and one from collection B gives you roughly a 90 percent chance of a collection A output. [1][2]
The Fandom wiki records that the contract used to be called the Arms Deal Contract and was renamed with the Operation Bravo update, which is also when it stopped being limited to a single collection. [2]
The float formula
The wear on the outcome skin is not random. Both wikis give the same calculation: [1][2]
f = x * (y - z) + z
f is the float of the outcome skin. x is the average float of the ten inputs. y and z are the maximum and minimum float caps of the skin you actually receive. [1][2]
The wiki's worked example: ten inputs averaging 0.10 into an output with a 0.00 to 0.50 range gives 0.10 * (0.50 - 0.00) + 0.00 = 0.05, which lands in Factory New. [1]
That is the whole reason people sort inputs by float. Cheap skins that have drifted up in wear drag the average with them, and the outcome lands in a worse wear band than the one you were aiming at.
StatTrak and what you cannot use
Ten StatTrak inputs produce a StatTrak output. Mix StatTrak and normal inputs and the output is normal, so the two categories never mix in one contract. [1][2]
Three kinds of skin are excluded as inputs. Knives and gloves cannot be used. Contraband skins cannot be used. And a skin that is the top grade of its own collection cannot be used, because there is nothing above it to trade into. The Fandom wiki's example is the Tec-9 Ossified, which is Mil-Spec but sits at the top of the Aztec Collection. [2]
Consumer Grade skins are not a possible outcome either. [2]
The knife rule, where the sources disagree
Counter-Strike Wiki says you cannot trade up to knife or glove rarity, and lists Extraordinary and Gold as out of reach. [1]
The Fandom Counter-Strike Wiki says the opposite, and puts a date on it. Following the October 22, 2025 update, five Covert skins can be traded up for one knife or one pair of gloves from a collection represented in the inputs, and five StatTrak Covert skins can produce one StatTrak knife. [2]
Valve's official update notes do not mention trade-up rules, so I cannot settle this from a primary source. [3] The contract screen in your own inventory is the only place the answer is authoritative, and it is worth checking before you commit five Covert skins to a knife attempt.
Is it worth doing
The contract is one-way. The ten inputs are destroyed. [1]
It pays when the expected value of every skin you could receive is higher than what you paid for the ten inputs. That needs current market prices for the whole possible output pool, not just the skin you want. The wiki lists three conditions: expected value above input cost, collections loaded with the valuable skins you are targeting, and the float formula keeping the wear where you want it. [1]
Rounding in the float calculation can also produce results you did not expect, so a near-miss in the math is not a near-miss in the outcome. [1]
FAQ
- Can I use any ten skins? No. They must be the same weapon grade, and none of them can be the top grade of its own collection.
- Where does the output come from? From one of the collections you put in, weighted by how many skins you contributed from each.
- Can I get a knife? The two wikis disagree. Counter-Strike Wiki says no. The Fandom wiki says five Covert skins can produce a knife since October 22, 2025.
- Does StatTrak carry over? Only if all ten inputs are StatTrak.
- Can I cancel after signing? The contract gives you one last confirmation prompt before it submits.
- Can I get a Consumer Grade skin? No. Contraband and Consumer Grade skins are not possible outcomes.