Most traders look at their win rate first. It feels like the most direct measure of whether a strategy works: you were right more often than you were wrong. The higher the number, the better the strategy. Except that is not how it works, and relying on win rate to judge a strategy leads directly to keeping losing systems and discarding profitable ones.
Win rate is one of the most watched numbers in the TradingView Strategy Tester, and one of the least informative on its own. This post explains exactly why, shows the numbers that actually predict long-term results, and ends with how to track the right metrics directly in your Pine Script strategy.
The problem with win rate in isolation
Win rate measures how often you are right. It says nothing about how much you make when you are right versus how much you lose when you are wrong. Those two figures, not your win rate, are what determine whether a strategy is profitable.
Consider two strategies run over 100 trades. Strategy A wins 70 of them, which sounds excellent. Strategy B wins only 35. Most traders would pick A immediately without looking further. Here is what the rest of the numbers say:
| Strategy A | Strategy B | |
|---|---|---|
| Win rate | 70% | 35% |
| Average win | $50 | $300 |
| Average loss | $200 | $100 |
| Expectancy per trade | −$25 | +$40 |
| Result over 100 trades | −$2,500 | +$4,000 |
Strategy A is losing money despite winning 70% of the time because every loss ($200) wipes out four wins ($50). Strategy B wins fewer than half its trades but each win is three times the size of each loss. The win rate told you nothing useful. Expectancy told you everything.
Expectancy: the number win rate obscures
Expectancy is the average amount you make or lose per trade over a large enough sample. The formula is straightforward: multiply the win rate by the average win, then subtract the loss rate multiplied by the average loss.
For Strategy A above: (0.70 × $50) − (0.30 × $200) = $35 − $60 = −$25 per trade. Negative expectancy. For Strategy B: (0.35 × $300) − (0.65 × $100) = $105 − $65 = +$40 per trade. Positive expectancy.
A positive expectancy means every trade adds value on average. A negative one means every trade costs you money on average, regardless of win rate. You can use the trade expectancy calculator to compute this from your own numbers. The win rate calculator is a natural starting point if you want to see your win rate first.
R-multiples: a cleaner way to think about the same thing
Expectancy expressed in dollars depends on position size and the instruments you trade. A more portable way to look at the same relationship is through R-multiples. R is the initial risk on a trade: the distance from entry to stop loss. Expressing wins and losses as multiples of R makes it possible to compare trades across different instruments and account sizes.
A trade that made twice the initial risk is +2R. One that lost the full stop is −1R. Average R-multiple across all trades is the expectancy in risk units. A positive average R-multiple means you have a mathematical edge. Use the R-multiple calculator to express any trade in these terms.
The breakeven relationship between win rate and payoff is worth memorising. At 1:1 reward-to-risk, you need 50% wins to break even. At 2:1, you only need 34%. At 3:1, you only need 25%. A strategy that wins 30% of the time at an average of 3R per win is more profitable than one that wins 60% of the time at 0.8R. Win rate is not irrelevant, but it only means something in context of the payoff.
Profit factor: a quick cross-check
Profit factor is gross profit divided by gross loss over the same period. A profit factor above 1.0 means more money came in than went out, which is the minimum requirement for a viable strategy. A factor of 1.5 or above is generally considered a reasonable starting point for live trading, though the number of trades in the sample matters enormously. A profit factor of 2.0 on 12 trades tells you almost nothing.
Profit factor is visible in the TradingView Strategy Tester and is a fast gut-check. A number below 1.0 means stop and investigate. A number above 1.0 means continue to the deeper analysis: expectancy, drawdown, and sample size. Use the profit factor calculator if you want to compute it from gross figures outside TradingView.
Sample size: the trap inside the trap
Even expectancy and profit factor can deceive you if the sample is too small. With 15 trades, a 70% win rate could easily be random variation. With 200 trades across different market conditions, it starts to mean something. The commonly cited minimum is 30 to 50 trades before any metric is worth acting on, and even that is a bare floor. A robust strategy needs hundreds of trades, ideally across different years and market regimes, before the statistics deserve real confidence.
This is also why cherry-picking the date range of a backtest is so dangerous. A high win rate and strong profit factor on a bull market from 2020 to 2021 may collapse entirely when tested on a range-bound or declining market. The statistics describe the sample, not the strategy in general.
The metrics worth watching instead
Win rate is fine as a secondary check once the primary metrics are healthy. The primary metrics are: expectancy (does the average trade add or subtract value), profit factor (is the system profitable in aggregate), maximum drawdown (how much did equity fall from peak before recovering), and sample size (are there enough trades to trust any of the above). Maximum drawdown matters because a strategy with 0.4R expectancy and a 60% drawdown is not tradeable regardless of how positive the expectancy is.
You can combine all of these using the Strategy Tester in TradingView once your rules are coded in Pine Script. The strategy you need to build is one where the position logic is correct first, and the statistics follow from that. PineScripter generates Pine Script v6 strategies from a plain-English description of your rules, so you can reach the Tester and start reading real numbers rather than estimating them. The guide to turning a trading idea into testable Pine Script covers the specification step that makes that work.
Disclaimer: PineScripter is a coding tool for Pine Script development. It does not provide financial advice and does not guarantee trading profits. Always backtest strategies thoroughly and understand the risks before live trading.