The input price is the best buy price across five markets for that exact wear; for regular contracts we take whichever of the normal and Souvenir version is cheaper and actually has enough listings. The outcome price is the same best price for the projected output wear, minus the selling fee. An outcome only counts if at least two independent markets confirm its price. Outcomes without a live price are counted as zero, so the estimate is conservative and their share is shown on its own line. Phase knives trade under one phaseless market hash whose price is the cheapest phase, so gold-tier expected values are understated.
How are the odds of a specific skin calculated?
A collection’s chance equals the share of its items in the contract, and inside that collection the result is drawn uniformly from every skin of the next rarity. Seven inputs from a collection with four outcomes give each of them 7/10 ÷ 4 = 17.5%, while three inputs from a collection with five outcomes give 3/10 ÷ 5 = 6%.
How is the output wear determined?
Each input’s float is normalized inside its own range: (float − min) ÷ (max − min). The average of those ten numbers is projected into the range of the skin you get: output float = min + average × (max − min). That is why the same set of inputs can land in different wears with very different prices.
Why a range instead of a single profit number?
Markets publish prices per wear bucket, not per float, so ten “Field-Tested” purchases can land anywhere inside that bucket. Usually the entire profit of a trade-up is one expensive outcome that stays in its good wear on a lucky float and drops into the next one on an unlucky one. The lower figure is the worst float inside the wear, the upper one the best, and the middle figure assumes you buy ten random listings without checking floats.
Can a contract give a knife or gloves?
Yes: since October 2025 five Covert items from one collection are exchanged for a knife or gloves from that collection. Five StatTrak™ Covert items give a StatTrak™ knife — StatTrak™ gloves do not exist. This is the only five-item contract; every other transition takes exactly ten inputs.
Does a contract accept Souvenir items?
Yes, since May 2026 Souvenir items go into a contract alongside normal ones: every Souvenir attribute — stickers and tournament marks — is removed and the result is a normal item of the next rarity. Souvenirs cannot go into a StatTrak™ contract. We pick the Souvenir version of an input when it is cheaper than the normal one and has enough listings.
How is this different from a normal trade-up calculator?
A calculator shows what a contract would cost at the average wear price. We show a basket you can buy: ten specific lots with floats, prices and links, plus the exact result float for that set.
Is there a free alternative to TradeUpSpy?
Yes, this page. Basket building, EV, ROI, outcome odds and lot links are free and need no account, and the lots are pulled from several markets at once instead of a single one.
How often is the data updated?
The top list is recomputed in the background every thirty minutes, and listings for a given skin are cached for ten minutes. Each basket page has a "Refresh listings" button that queries the markets again.
Why does a basket sometimes fail to assemble?
If the markets do not have ten listings with the required float and price, the basket remains incomplete and shows the number found. Lower-tier transitions fill more often than knife contracts.
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