Win Rate Calculator with Costs & Confidence

Enter your trade sample and all-in cost per trade. The calculator shows the observed win rate with a 95% confidence interval, then adjusts expectancy, profit factor, breakeven rate, and total P&L for commissions and fees.

Your trade sample

After-cost results

Observed win rate
45.0%
95% CI 35.6–54.8%
Net expectancy / trade
$47.50
$52.50 gross − $5.00 cost
Net profit factor
1.56
after-cost gains ÷ losses
Cost-adjusted breakeven
34.4%
minimum rate for zero expectancy
Total net P&L
$4,750.00
100 closed trades
Sample strength
useful
100–199 trades

The observed 45.0% win rate is above the 34.4% after-cost breakeven estimate, but the 35.6–54.8% interval shows the remaining sampling uncertainty.

Formulas and Worked Example

Observed win rate

wins ÷ (wins + losses)

Net expectancy

(win rate × average win) − (loss rate × average loss) − cost per trade

Net profit factor

sum of positive after-cost trade outcomes ÷ absolute sum of negative after-cost outcomes

Cost-adjusted breakeven

(average loss + cost) ÷ (average win + average loss)

Worked example: 100 trades

With 45 wins, 55 losses, a $300 average win, a $150 average loss, and $5 cost per trade: observed win rate is 45.0% (95% Wilson interval 35.6–54.8%), net expectancy is $47.50 per trade, total net P&L is $4,750, net profit factor is 1.56, and the cost-adjusted breakeven rate is 34.4%.

Methodology & Limitations

How the calculation works

  • All averages are treated as gross realized outcomes; the entered all-in cost is deducted once from every trade.
  • The 95% range is the Wilson score interval for a binomial proportion, which remains finite at 0% and 100% observed win rates.
  • Sample labels use fixed trade-count bands: preliminary (<30), early (30–99), useful (100–199), and stronger (200+).

What this cannot tell you

  • The model assumes trades are comparable and independent. Correlated setups, changing market regimes, and execution drift can make the interval too optimistic.
  • A single average cost cannot capture variable slippage, partial fills, tiered commissions, or contract-specific fees.
  • Historical positive expectancy does not establish that a strategy has a durable edge or will be profitable in live trading.

Formula review: July 20, 2026. Maintained by TestMax. Results are educational estimates based on user inputs and simulated examples. They are not investment advice, a performance forecast, or a substitute for current exchange, broker, or firm rules.

Questions or corrections? Contact us. See our Privacy Policy and Terms of Service.

Frequently Asked Questions

How do trading costs change win rate calculations?

Costs do not change the observed win percentage, but they reduce every trade result. Net expectancy equals gross expectancy minus cost per trade. The cost-adjusted breakeven rate is (average loss + cost) ÷ (average win + average loss). If cost is greater than the average win, even a 100% win rate cannot produce positive expectancy.

What does the 95% win-rate confidence interval mean?

It is a range of win rates compatible with the observed sample under a binomial model. This calculator uses the Wilson score interval because it stays well behaved for small samples and at 0% or 100% observed win rates. It quantifies sampling uncertainty; it does not prove the strategy will keep the same win rate.

How many trades do I need before my win rate is meaningful?

There is no universal cutoff. The calculator labels fewer than 30 trades preliminary, 30–99 early, 100–199 useful, and 200 or more stronger. Those labels are practical communication guides, not proof of statistical validity. Regime changes, correlated trades, and changes in execution can matter even with a large sample.

What is a good win rate for day trading?

There is no universally good win rate. A 40% win rate can be profitable with large average wins, while a 60% win rate can lose money when losses and costs are too large. Judge win rate with net expectancy, net profit factor, and the uncertainty around the observed rate.

What is net expectancy?

Net expectancy is the estimated average after-cost P&L per trade: (win rate × average win) − (loss rate × average loss) − cost per trade. A positive historical expectancy is descriptive, not a guarantee that the same edge will continue.

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