CS2 trade up contracts have a reputation as a pure draw, and that is half right. Which skin comes out is random. What condition it comes out in is fixed arithmetic you can work out to three decimal places before you press confirm.
What the contract does
Ten skins of the same rarity go in, they are consumed permanently, and one item a single tier higher comes back. There is no undo and no partial input: nine will not work and eleven will not either.
Two restrictions catch people while collecting inputs. StatTrak only combines with StatTrak, and souvenir items are excluded from contracts entirely.
One tier higher means exactly that. Consumer becomes industrial, industrial becomes mil-spec, and so on up to the ceiling where contracts stop.
Where the output comes from
Every skin belongs to a collection. The game looks at which collections your ten inputs come from and splits the odds in proportion to how many came from each.
Seven from one collection and three from another gives seventy percent for an output from the first and thirty for the second. That share then divides across the skins available at the higher tier inside whichever collection wins.
Which produces the advice everyone repeats without explaining: ten inputs from a single collection means a hundred percent chance the output comes from it. That does not make the result more valuable. It makes the list of possible results short enough to plan around.
The float formula, which nobody prints
This is the part worth the reading time.
The wear of the output is not drawn. The game takes the float of each of the ten inputs, rescales it to a zero to one position inside that skin’s own range, averages those ten numbers, and maps the average onto the range of whatever comes out.
Written out: output = outputMin + average x (outputMax – outputMin).
The normalisation step is where intuition fails. Skins have different wear ranges. A skin capped at 0.40 holding a float of 0.05 does not count as 0.05, it counts as 0.125, because that is how far along its own range it sits.
So a batch of Factory New inputs does not guarantee a Factory New result. Position within the range decides, not the number printed on the item.
Doing it by hand once
- List the ten floats with each skin’s range beside it.
- Normalise each one: subtract the minimum, divide by the range.
- Average the ten results.
- Take the range of the output you want and put the average into the formula above.
- Check where that lands for every possible skin in the pool, since each has its own range.
That is tedious, and that is why calculators exist. It is still worth doing once by hand, because that is when it becomes obvious that two batches described identically as “all Factory New” produce entirely different outputs.
Where to get inputs without overpaying
Since the result depends on what goes in, sourcing the inputs is the actual work rather than clicking confirm.
The cheapest source costs nothing: weekly rewards for playing. Over a few months that accumulates into dozens of low rarity items, which is precisely what a contract consumes.
The second is your own inventory. Items you have never equipped have zero use value to you and full value as an input.
The third and most expensive is buying to order on the market. That only works if you calculated first, because every purchase carries a fee and those few percent turn a marginal contract into a losing one. The free routes are collected in our guide to free CS2 skins without a deposit.
Where the ladder stops
A point worth stating plainly, because a lot of people assume the ladder eventually reaches a knife.
Contracts operate within ordinary weapon skins and stop at one of the upper rarity tiers. Knives and gloves sit outside the system and are not a possible output of any contract, ever.
So ten contracts in a row bring you no closer to the most expensive items in the game. They bring you closer to more expensive weapon skins, and there the road ends.
If a specific knife is the goal, the only sensible route is selling what you have and buying it. Everything else is a longer path to the same place at a worse exchange rate.
When CS2 trade up contracts actually pay
| Situation | Worth it |
|---|---|
| a pile of cheap drop skins | yes, the alternative is selling them for pennies |
| chasing a specific skin from one collection | sometimes, if the inputs cost less than the target |
| chasing an unusually low float | yes, for some items this is the only way one exists |
| buying inputs to turn a profit | rarely, fees and input premiums eat the margin |
| raising inventory value quickly | no, that is what buying and selling is for |
The first row is the only unconditional yes. Weekly drop skins are worth close to nothing on the market and carry real value as contract inputs, which is a better outcome than letting them sit.
Why most contracts lose money
The market prices skins, and the market knows the same formulas you do. Items that make good inputs are more expensive precisely because they make good inputs, and that premium consumes most of the theoretical margin.
Then there are fees, both when buying inputs and when selling the output. How much disappears at each step is set out in our breakdown of how much you lose selling CS2 skins.
Treat a contract as a way to use worthless inputs or to obtain one specific item, not as an earning mechanism. Approached that way it is genuinely useful.
The one case where the maths pays
Some skins effectively never exist in the best condition, because their wear range does not reach that far. The only way such an example comes into existence is a contract with carefully chosen inputs.
Those items have their own market and prices disconnected from appearance, because the buyer is paying for a number rather than for anything visible. The difference between 0.002 and 0.01 is invisible on the model and can mean several times the price.
That is the one area where running the formula from this article converts directly into money. Everywhere else it converts into not being surprised by what came out.
Contracts and what your inventory is really worth
There is a second reason to run contracts that has nothing to do with the output, and it only becomes obvious once you total up what you own.
An inventory full of cheap drops looks more valuable than it is, because every item is counted at its listed price. In practice nobody will buy most of them, and the fee on what does sell removes what little was there.
A contract is one of the few operations that converts that dead weight into a single item with a real price. That is housekeeping rather than profit, and treating it as housekeeping is what keeps expectations honest.
How to total an inventory without fooling yourself is set out in our piece on CS2 inventory value.
Three expensive mistakes
Mixing collections without a reason. Each additional collection adds possible outputs, including the ones you did not want.
Using inputs whose ranges you never checked. Two items that look identical in your inventory can sit at completely different positions in their own ranges and shift the result by a full wear tier.
Expecting the next contract to make up for the last one. Each is independent, previous results have no bearing, and there is no such thing as a run.
What happens to the output
The item lands in your inventory with a trade restriction, exactly as an item from any other source does.
That means a week before you can sell or trade it, and the price can move in either direction during that week. If selling was the plan, build that into the timing rather than discovering it afterwards.
How the restriction works and what starts the clock is in our piece on the CS2 trade lock.
Frequently asked questions about CS2 trade up contracts
How many skins does a contract need?
Exactly ten, all of the same rarity. Nothing else is accepted.
Can you predict the outcome?
Partly. The pool and the collection odds are known in advance, the specific skin is drawn, and the wear is calculable.
Are single collection inputs better?
They guarantee the output comes from that collection. They do not raise its value, they narrow the range of surprises.
Can StatTrak mix with normal items?
No. StatTrak combines only with StatTrak, and souvenir items cannot be used at all.
Why did I get a worse wear than my inputs had?
Because position inside each skin’s own range counts, not the raw number. A narrow range contributes more than it appears to.
Can a contract produce a knife?
No. Knives and gloves are outside the contract system entirely.
Can you make money doing this?
Occasionally a specific combination works out, but the market prices good inputs accordingly. Treat it as a use for cheap skins rather than as income.
Last updated: September 2026
Mechanics and the wear formula come from public documentation and from tools that calculate contracts, checked in September 2026. Collection contents and prices change, so recalculate any specific batch before confirming it.
