Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
Expected value per bet
$12.50
EV as % of stake
12.5%
Break-even win probability
40.0%
Your edge vs. break-even
5.0%
Profit if bet wins
$150.00
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter stake ($).
- 2Enter odds offered (american).
- 3Enter your estimated true win probability (%).
- 4Read your expected value per bet on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Expected value tells you what a bet is worth on average if you could place it thousands of times. A bet with positive EV isn't guaranteed to win — most positive-EV bets still lose plenty of the time — but making the same type of decision repeatedly will be profitable over a large enough sample. This calculator takes your stake, the offered odds, and your own honest estimate of the true win probability (not the market's implied probability) and computes the expected profit per bet, the EV as a percentage of stake, and the break-even probability the odds require. The hardest part of this calculator isn't the math, it's the input: your probability estimate needs to come from real research, a model, or a documented edge, not a hunch dressed up as confidence. Bettors consistently overestimate their own win probability, which turns math that looks positive on paper into a losing proposition in practice. Use this to quantify a specific bet you're considering, and be skeptical of any estimate that conveniently produces a large edge.
Worked example
Using the values the calculator loads with:
Inputs
- Stake: 100 $
- Odds offered (American): 150
- Your estimated true win probability: 45 %
Results
- Expected value per bet: $12.50
- EV as % of stake: 12.5%
- Break-even win probability: 40.0%
- Your edge vs. break-even: 5.0%
- Profit if bet wins: $150.00
What each field means
Inputs
- Stake ($)
- The stake used in the calculation, measured in $. Starts at 100 $ so you have a working example on load.
- Odds offered (American)
- The odds offered (american) used in the calculation. Starts at 150 so you have a working example on load.
- Your estimated true win probability (%)
- The your estimated true win probability used in the calculation, measured in %. Starts at 45 % so you have a working example on load. Accepted range: 0–100 %.
Results
- Expected value per bet
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- EV as % of stake
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Break-even win probability
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Your edge vs. break-even
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Profit if bet wins
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
If a bet has positive EV, why does it still lose so often?
EV describes the long-run average, not any single outcome. A bet with a true 45% win probability priced generously at +150 has positive EV, but it still loses 55% of the time on any given try. Positive EV only pays off over a large enough number of similar bets, which is why bankroll management matters as much as finding the edge.
What's the difference between EV and the break-even win rate?
Break-even win rate is the probability required for the bet to have exactly zero EV, purely a function of the odds. EV requires you to also plug in your own probability estimate. If your estimate exceeds the break-even rate, EV is positive; if it's below, EV is negative, regardless of how the bet turns out.
How do I get a reliable probability estimate instead of just guessing?
Serious bettors build models from historical data, injury reports, and situational trends, or use a no-vig market consensus from multiple sharp books as a baseline and adjust from specific information. If your estimate is just a feeling about a favorite team, treat any resulting EV number as unreliable.
Does a small positive EV matter?
Yes, if you can repeat the process at scale. A 3% EV edge sustained across thousands of similarly-sized bets compounds meaningfully, the same way a small edge in card counting or index investing compounds. On a single bet, a 3% edge is nearly invisible against normal variance.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Related tools
Break-Even Win Rate Calculator (-110 and Beyond)
The win percentage you need at any odds just to break even.
Implied Probability Calculator
See the win probability a betting line is actually pricing in.
Closing Line Value (CLV) Calculator
Measure whether you beat the market's final price, independent of the result.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Expected Value (EV) Bet Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/expected-value-bet-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/expected-value-bet-calculator" target="_blank" rel="noopener">Expected Value (EV) Bet Calculator — RevenueLab</a> (2026).</p>
Source: [Expected Value (EV) Bet Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/expected-value-bet-calculator) (2026).