The trade-up contract is CS2's one crafting recipe that climbs the rarity ladder: feed it ten skins of the same grade and it returns a single skin one tier higher. Everything about the outcome — which skin, which collection, how clean the float — is decided by the inputs you pick, making it a game of probability rather than luck.
How the outcome pool is built
A contract takes exactly 10 skins of the same rarity grade and returns one random skin of the next grade up — the ladder runs Consumer, Industrial, Mil-Spec, Restricted, Classified, Covert. The pool of possible outcomes is made of the next-grade skins from the collections your inputs come from. Load more inputs from a single collection and you raise the chance of landing that collection's outcome, which is the main lever you control.
The output float is derived from the average of your ten input floats, then remapped onto the outcome skin's own float range. That is why skilled trade-uppers deliberately buy low-float inputs: a clean average pushes the result toward Factory New, which is usually where the value sits.
The hard rules
A few constraints are absolute and worth memorizing before you spend anything.
- StatTrak stays with StatTrak. ST inputs produce ST outputs; you cannot mix ST and non-ST in one contract.
- No souvenirs. Souvenir items cannot be used in a trade-up at all.
- Covert is the ceiling. Covert-grade skins cannot be traded up, so contracts never produce knives.
- Same grade in. All 10 inputs must share one rarity grade.
- Float is averaged. The result's wear comes from the input average, not from any single skin.
Profit is pure math
Whether a trade-up makes money is not a vibe — it is an equation. On one side sits your total input cost; on the other, the value of every possible output weighted by its probability. If the probability-weighted output value clears the input cost after fees, the contract is +EV; if not, you are donating.
Because both the odds and the prices shift constantly, running the numbers by hand is slow and error-prone. Our trade-up calculator computes the full probability table and expected value at live prices for any combination you sketch, and the knife trade-up calculator applies the same math to the priciest top-grade contracts.