CS2 Trade Up Contracts: How They Work, Odds & Float Formula
Trade up contracts let you turn ten unwanted skins into one skin of the next rarity up, and since late 2025, five Covert skins into a knife or gloves. Understanding the maths is the difference between a profitable contract and burning skins for nothing. This guide covers the rules, how to calculate your odds and the float formula that every CS2 trade up calculator is based on.
What is a trade up contract?
A trade up contract is a feature in CS2’s inventory. You hand over a set number of skins of the same rarity, and the game gives you back a single skin from the next rarity tier. The new skin always comes from a collection that one of your input skins belongs to.
The rules
- Standard contracts use 10 skins of the same rarity (for example, ten Mil-Spec skins give one Restricted skin).
- Inputs can’t be mixed between StatTrak™ and normal. Ten StatTrak inputs give a StatTrak output.
- Souvenir skins can’t be used, and nor can items that are already at the top of a collection.
- The output is one rarity higher and comes from one of the input skins’ collections.
- Covert → knife or gloves: since Valve’s October 2025 update, five Covert skins can be traded up for a rare special item (a knife or gloves). StatTrak Covert inputs give a StatTrak knife. Gloves can’t be StatTrak.
Valve tweaks these rules from time to time, and its own support pages haven’t always kept up with the game. If something here doesn’t match what you see in game, the game is the final word.
How trade up odds work
For a standard 10-skin contract, each input “buys” a share of the odds for its own collection. The chance of a particular output skin is:
Chance = (number of inputs from that collection ÷ total inputs) ÷ number of possible outputs in that collection’s next tier
Worked example
You put in 7 skins from Collection A and 3 from Collection B. Collection A has 2 possible outputs in the next tier, and Collection B has 4.
| Output | Calculation | Chance |
|---|---|---|
| Each Collection A skin | (7 ÷ 10) ÷ 2 | 35% |
| Each Collection B skin | (3 ÷ 10) ÷ 4 | 7.5% |
So the two A outputs add up to 70%, and the four B outputs add up to 30%. This is why experienced traders use “filler” skins from collections with only one valuable output in the next tier, so the odds land where they want them.
For Covert-to-knife contracts, Valve hasn’t published exactly how the knife or glove pool is chosen. Community testing is still being argued over, so treat any calculator’s knife odds as an estimate.
The trade up float formula
The output skin’s float (wear) is worked out from your inputs’ floats. In CS2 the game normalises each input float against that skin’s own float range first, which matters because many skins can’t reach the full 0–1 range.
- Normalise each input: (input float − that skin’s min float) ÷ (that skin’s max float − min float).
- Average the normalised values across all inputs.
- Map to the output skin: output float = output min + average × (output max − output min).
Example
Your ten inputs average a normalised value of 0.05, and the output skin’s range is 0.00–0.80. The output float is 0.00 + 0.05 × 0.80 = 0.04, which is Factory New (below 0.07). Now you can see why traders pay a premium for low-float inputs: they’re the only reliable way to guarantee a Factory New or Minimal Wear result.
Not sure what float ranges mean? Read our CS2 float value and wear guide first.
How CS2 trade up calculators work
A trade up calculator simply automates the maths above. You enter your inputs, and it:
- looks up each skin’s collection and float range;
- works out the chance of every possible output;
- predicts the output float (and so the wear) of each outcome;
- multiplies each outcome’s chance by its market price to give an expected value, which it compares with the cost of your inputs.
The result is only as good as the prices it uses. Market prices move quickly, and selling a skin costs fees, so check live prices and allow for fees before committing.
Tips for profitable trade ups
- Look at expected value, not the best case. A contract with a 10% chance of a great skin can still lose money on average.
- Control your odds with filler collections. Inputs from collections with a single, valuable output keep the odds concentrated.
- Buy floats for the wear you need. Work out the maximum average float that still gives your target wear, then buy inputs below it.
- Allow for fees and trade protection. Steam Market fees and the 7-day trade protection on traded items both affect how quickly and profitably you can sell.
- Start small. Test a cheap Mil-Spec contract before risking expensive Classified or Covert skins.
FAQs
How many skins do you need for a trade up in CS2?
Ten skins of the same rarity for a standard contract, or five Covert skins for a knife or gloves trade up.
Can you trade up StatTrak and normal skins together?
No. All inputs must be StatTrak or all normal, and the output matches.
Can you get a knife from a trade up?
Yes. Since October 2025, five Covert skins can be traded up for a knife or gloves.
Are trade ups profitable?
Some are, but most aren’t on average. Profitable contracts usually rely on careful input selection, low floats and up-to-date prices. Always calculate the expected value first.
Want to trade up with skins you already own? Find out what they’re worth with our guide to checking your CS2 inventory value, or compare the best CS2 trading sites to source inputs.
