Knife Trade-Up EV Calculator
Estimate expected value, profit/loss, and break-even knife price for a trade-up attempt.
Contract Costs
Outcome Assumptions
Tip: Make sure your total chance equals 100% for accurate expected value math.
What this knife trade-up calculator does
This tool helps you model a trade-up as a probability problem instead of a gut-feel gamble. You enter your total contract cost, estimate your likely outcomes, and the calculator returns your expected value (EV), expected profit/loss, ROI, and break-even knife value.
If you trade in skin economies (such as CS2-style trade-up systems or similar item markets), EV is the most useful number to track. A single opening can win big or lose hard, but over many attempts, EV tells you whether the strategy is mathematically favorable.
How to use it correctly
1) Start with realistic input costs
Include your true average item purchase cost, not just the lowest listing you happened to see once. If you bought 10 fillers at different prices, use the average. Add extra costs if needed (for example, transfer fees, conversion losses, or small spread costs).
2) Use believable probabilities
Probabilities should come from the contract pool you are actually using. If your estimated knife chance is too optimistic, EV will look much better than reality. A small probability error can flip a seemingly profitable contract into a losing one.
3) Always apply selling fees
Most item markets take a fee. Ignoring that fee can overstate your returns by a lot. The calculator deducts fee from your outcome value before EV is computed, which is the correct approach for a practical liquidation estimate.
Core formulas behind the calculator
- Total Contract Cost = (item count × average input price) + extra costs
- Net Outcome Value = market value × (1 − fee rate)
- Expected Value (EV) = Σ(probability × net outcome value)
- Expected Profit = EV − total contract cost
- ROI = (expected profit ÷ total contract cost) × 100
Practical trading advice
Use EV as a filter, not a promise
Positive EV means your assumptions suggest a favorable long-run edge. It does not guarantee that your next attempt makes money. Variance can dominate short runs.
Track outcomes over time
Keep a log: input cost, resulting item, net sale value, and profit/loss. This gives you real data to compare against your expected model and helps you identify bad assumptions quickly.
Watch liquidity and spread
A knife valued at a high listing price might still sell lower in practice. If quick sale is needed, adjust your value assumptions downward. EV is only as good as your expected exit price.
Mini example
Suppose your contract costs $180 total. If regular outcomes are common and net around $104.40 after fee, while a 10% knife hit nets $1,261.50, your EV is the weighted average of those two outcomes. If EV exceeds $180, you have a positive expected edge. If it does not, you are likely paying for entertainment rather than edge.
FAQ
Can this calculator guarantee profit?
No. It estimates expected value based on your inputs. Real market prices and probabilities can shift.
Why can I still lose if EV is positive?
Because single outcomes are random. Positive EV is a long-run property, not a short-run certainty.
Should I include taxes?
If taxes apply to your jurisdiction and selling platform, include them in extra costs or adjust expected sale values down.