How CS2 Trade-Up Contracts Work: Input Skins, Float, and Expected Value

What Is a CS2 Trade-Up Contract?

A trade-up contract (Contract) in CS2 (Counter-Strike 2) allows you to trade 10 skins of the same rarity tier for 1 skin of the next higher rarity from any of the input skins' collections.

Rarity progression: Consumer Grade → Industrial Grade → Mil-Spec → Restricted → Classified → Covert → Contraband (knives/gloves — not obtainable via contracts)

Rule: All 10 input skins must be the same rarity tier; the output is one tier higher.

How Output Skin Selection Works

The output is randomly selected from the pool of all skins one tier higher that exist across all collections represented by your 10 input skins.

Critical rule: Each collection's output skins appear in proportion to how many of your 10 inputs come from that collection.

Example: - 6 inputs from Collection A → 60% chance of Collection A's higher-tier skins - 4 inputs from Collection B → 40% chance of Collection B's higher-tier skins

If Collection A has 3 possible outputs, each has probability: 0.60 / 3 = 20% If Collection B has 2 possible outputs, each has: 0.40 / 2 = 20%

Float Value Calculation

The output skin's float (wear level) is determined by your input skins' floats:

Output Float = (Average input float) × (MaxFloat − MinFloat) + MinFloat

Where MaxFloat and MinFloat are the output skin's float range limits.

Wear tier thresholds: | Condition | Float Range | |-----------|------------| | Factory New (FN) | 0.00–0.07 | | Minimal Wear (MW) | 0.07–0.15 | | Field-Tested (FT) | 0.15–0.38 | | Well-Worn (WW) | 0.38–0.45 | | Battle-Scarred (BS) | 0.45–1.00 |

Example: 10 inputs average float = 0.12 (MW range) Output skin has MinFloat = 0.00, MaxFloat = 0.80

Output float = 0.12 × (0.80 − 0.00) + 0.00 = 0.096 → Minimal Wear

Expected Value (EV) Calculation

EV = Σ(Probability × Value of each possible output)

Example trade-up: - Total input cost: 10 skins × $5 each = $50 - Possible outputs: Skin A (50% probability, $80 value), Skin B (50%, $40 value) - EV = (0.50 × $80) + (0.50 × $40) = $40 + $20 = $60 - Profit EV = $60 − $50 = +$10 expected profit

But factor in Steam Market fees (15% seller fee): - Net EV = $60 × 0.85 = $51 after selling - Net profit = $51 − $50 = +$1 (barely profitable)

Using a Trade-Up Calculator

Input fields: 1. 10 skin names and conditions (or float values) 2. Purchase price for each input

Calculator outputs: 1. All possible output skins and their probabilities 2. Output float range based on input floats 3. Current market prices for each output 4. Expected value and breakeven analysis

Key metric: EV / Total input cost > 1.15 (covers Steam 15% fee) = potentially profitable

Common Trade-Up Strategies

• Float targeting: Use high-float inputs to push output float into a desirable condition tier for a specific skin
• Concentrated collection: Put 10 inputs from one collection to get 100% probability on specific outputs
• Diversified high-value: Spread across collections with expensive outputs at each probability weight