The risk/reward ratio calculator above compares how much you stand to lose against how much you stand to gain on a trade, then goes one step further and tells you the win rate you'd need just to break even, plus the expectancy per share once you plug in a realistic estimate of how often you actually win. Enter your entry price, stop-loss, and target, and every figure updates instantly.
Arb Digital built this as part of a small library of free trading calculators because risk/reward is one of the few numbers a trader controls completely before the trade even happens β unlike the market's next move, which nobody controls. Getting this ratio right, and understanding what it implies about the win rate you need, separates traders who survive from traders who don't.
What This Risk/Reward Ratio Calculator Does
Every trade has two prices that matter before you ever place it: where you get out if you're wrong (the stop-loss) and where you get out if you're right (the target). The distance between your entry and the stop is your risk. The distance between your entry and the target is your reward. Dividing reward by risk gives you the ratio β a 3:1 ratio means you stand to make three dollars for every dollar you're risking.
This calculator also solves for the win rate you'd need just to break even at your current ratio, and, if you supply an honest estimate of your actual win rate, it calculates expectancy β the average amount you'd expect to make or lose per share, per trade, over a large number of similar trades. Expectancy is the number that actually determines whether a trading approach is profitable over time; the ratio alone is not enough.
How to Use It
- Enter your entry price β the price at which you plan to open the trade.
- Enter your stop-loss price β the exact level that invalidates the trade idea and triggers an exit.
- Enter your target price β the level at which you plan to take profit.
- Optionally, enter an estimated win rate based on your trading history or backtest results. Be honest β an inflated number defeats the purpose.
- Hit Calculate to see the ratio, the break-even win rate, and expectancy per share.
The Formula Behind the Numbers
The reward per share is the target price minus the entry price (for a long trade). The risk per share is the entry price minus the stop-loss price. The ratio is simply reward Γ· risk, commonly expressed as "X:1." The break-even win rate β the minimum percentage of trades you'd need to win, at this exact ratio, just to net zero over time β is calculated as risk Γ· (risk + reward). A 3:1 ratio, for example, has a break-even win rate of 25%, since 1 Γ· (1 + 3) = 0.25.
Expectancy per share is calculated as (win rate Γ reward per share) β ((1 β win rate) Γ risk per share). This single number tells you, on average, how many dollars per share you'd expect to gain or lose on a trade like this one, repeated many times. The concept of expectancy in trading system evaluation is discussed by financial educators and is closely related to the expected value concept explained in Investopedia's overview of expectancy, a standard reference for retail trading education.
Why You Can Be Wrong 60% of the Time and Still Profit at 3:1
This is the counterintuitive heart of risk/reward math: win rate alone tells you almost nothing about profitability. A trader who wins only 40% of the time but consistently trades at a 3:1 ratio has a break-even win rate of just 25% β meaning every percentage point of win rate above 25% is pure expected profit. At a 40% win rate and a 3:1 ratio, the expectancy per dollar risked works out to roughly (0.40 Γ 3) β (0.60 Γ 1) = 1.2 β 0.6 = +0.6, a healthy positive number even though the trader is "wrong" most of the time.
Compare that to a trader who wins 70% of the time but only at a 1:3 ratio β reward smaller than risk, common among traders who take quick profits but let losers run. That trader's break-even win rate is 75% (3 Γ· (3+1)), so a 70% win rate, which sounds impressive, is actually below break-even: expectancy is (0.70 Γ 1) β (0.30 Γ 3) = 0.7 β 0.9 = β0.2 per dollar risked. A high win rate with a poor ratio can still bleed an account dry, one small win and one large loss at a time.
This is precisely why professional traders and risk-management educators, including material referenced by FINRA's investor education on day-trading risk, emphasize that win rate in isolation is close to meaningless β it must always be evaluated alongside the ratio it's paired with.
Reading the Break-Even Win Rate
The break-even win rate is arguably the most actionable number this calculator produces, because it converts an abstract ratio into a concrete, comparable question: "based on my trading history, do I actually win more often than this?" If your ratio implies a 40% break-even win rate and your honestly tracked win rate over the last 50β100 trades is 45%, you have a thin but real edge. If your tracked win rate is 30%, the setup is losing money on average regardless of how good it feels in the moment.
This is also a useful filter before you ever take a trade: if a setup's ratio implies a break-even win rate higher than what similar setups have historically achieved, the trade doesn't need to be taken just because a chart pattern looks clean. Ratio and realistic win rate have to be evaluated together, every time.
Expectancy Is the Number That Actually Matters
Ratio tells you the shape of a single trade. Win rate tells you how often trades like it tend to work. Expectancy combines both into the one figure that predicts long-run outcomes: your average result per share, per trade, if you repeated this exact setup hundreds of times. A positive expectancy, compounded across enough trades with consistent position sizing, is the mathematical basis of a profitable trading approach β not any single win, and not any single loss.
It's worth stressing that expectancy is only as good as the win-rate estimate that feeds it. A guessed or hoped-for win rate produces a meaningless expectancy figure. The honest version of this exercise requires a trading journal or backtest with enough sample size β most educators suggest at least 30β50 trades β before the win-rate input can be trusted.
A great risk/reward ratio still needs the right number of shares behind it β run the trade through our position size calculator next.
Position Size Calculator All Free ToolsCommon Mistakes to Avoid
- Chasing a high ratio with an unrealistic target. A 10:1 ratio is meaningless if the target is a price the stock has never reached.
- Ignoring your actual win rate. The ratio alone doesn't tell you whether a strategy is profitable β always compare it to your break-even win rate.
- Moving the stop or target after entry to "improve" the ratio. The ratio should be locked in before the trade, based on real chart levels, not adjusted after the fact to feel better.
- Using a win rate from too small a sample. Ten trades is not enough data to trust an expectancy calculation.
- Forgetting commissions and slippage. Real-world costs shrink both your reward and your effective ratio slightly on every trade.
Adjusting the Ratio When the Trade Doesn't Work
Sometimes plugging real numbers into this calculator reveals that a setup you were excited about doesn't actually clear a sensible risk/reward bar β the target is too close to the entry relative to the distance of a logical stop, or the only stop that makes technical sense sits far enough away that the reward no longer compensates for it. When that happens, the discipline is to walk away or wait for a better entry, not to shrink the stop until the ratio looks acceptable on paper. A stop moved closer purely to improve the math is a stop that no longer reflects where the trade idea is actually invalidated, and it tends to get hit by ordinary price noise rather than a genuine reversal.
It's also worth running the same setup through the calculator with a slightly more conservative target β say, the midpoint of a resistance zone rather than its far edge β since real fills rarely land on the exact best-case price. A ratio that still looks attractive after that haircut is a more trustworthy number than one that only works if every price in the trade lands perfectly in your favor.
Related Free Tools From Arb Digital
Once you know your ratio and expectancy, the Position Size Calculator tells you exactly how many shares to trade, the Options Profit Calculator extends this same thinking to calls and puts, the Stock Profit Calculator models the dollar outcome of a winning trade, and the Sharpe Ratio Calculator looks at risk-adjusted return across your whole portfolio rather than one trade at a time. See every calculator at our free online tools hub.
Frequently Asked Questions
Many traders target at least 2:1 or 3:1, but there's no universal answer β a ratio is only "good" relative to the win rate a strategy actually achieves over a meaningful sample of trades.
Break-even win rate equals risk Γ· (risk + reward). At a 3:1 ratio, that's 1 Γ· 4, or 25% β the minimum win rate needed to avoid losing money over time.
Yes β if the risk/reward ratio is high enough, a strategy can be profitable while losing more often than it wins, as long as the actual win rate stays above the break-even win rate for that ratio.
It's the average amount you'd expect to gain or lose per share, per trade, if you repeated a setup with the same ratio and win rate many times over.
From a trading journal or backtest covering a reasonably large sample of similar trades β most educators suggest at least 30β50 trades before trusting the figure.
No single trade is guaranteed anything β the ratio and expectancy describe an average outcome across many repetitions of a similar setup, not the result of any one trade.
This tool provides general estimates for educational purposes only and is not financial, tax, legal, or medical advice. Figures are illustrative; consult a licensed professional for decisions.
