Two numbers to read together
Win rate tells you how often you win, risk/reward how much you win compared with how much you lose. On their own they mislead: you can lose money with 70% winning trades and make money with 35%.
The break-even win rate
Minimum win rate = 1 ÷ (1 + R:R). With an R:R of 1:1 you need to win more than 50% of the time, with 1:2 more than 33%, with 1:3 more than 25%. Below that threshold the system loses, however precise it looks.
Expectancy
Expectancy = (win rate × average win) − (loss rate × average loss). In R it's even simpler: the average R result of all your trades. An expectancy of +0.3R means that each trade, on average, earns you 30% of what you risk.
Example: 40% wins of +2R and 60% losses of −1R. Expectancy = 0.4 × 2 − 0.6 × 1 = +0.2R per trade.
What to look at in your journal
Calculate win rate and expectancy separately by setup and hour, with at least 30 trades per group. Often a single setup is carrying everything else: cutting the losing ones is the quickest improvement you can make.