Enter American odds and your estimated win probability to instantly calculate expected value, implied probability, breakeven win rate, and your edge. No signup required.
The hardest part of EV calculation is getting an accurate probability estimate. If you want help with that, we recommend Juice, an iOS app that uses three AI models (ChatGPT, Claude, and Gemini) to estimate probability and calculate EV for any sports bet. It also compares odds across 18 sportsbooks.
Expected value (EV) is the foundation of profitable sports betting. At its core, it answers one question: if you placed this exact bet thousands of times under the same conditions, would you make money or lose money on average? A positive expected value (+EV) means you expect to profit over time. A negative expected value (-EV) means the bet costs you money in the long run. If the odds you are working with are in decimal or fractional format, convert them to American first using our Odds Converter before entering them here.
This concept is borrowed directly from professional gambling and finance. Casino operators, poker players, and quantitative traders all think in terms of expected value. A single bet can always win or lose due to luck, but over hundreds of similar bets, positive EV reliably produces positive results while negative EV reliably destroys bankrolls.
You want to bet $100 on a team covering the spread at -110 odds. Your analysis suggests they have a 57% chance of covering.
EV = (0.57 × $90.91) - (0.43 × $100) = $51.82 - $43.00 = +$8.82
This is a +EV bet. Over hundreds of similar opportunities, you would expect to earn approximately $8.82 for every $100 wagered.
The calculator requires three inputs:
The calculator then returns five outputs: Expected Value in dollars, EV as a percentage of your stake, implied probability embedded in the odds, breakeven win rate, and your edge percentage. The result is color-coded green for +EV and red for -EV.
The dollar amount you expect to win or lose on average per bet at this stake size. A result of +$5.50 means that if you made this bet 100 times, you would expect to net roughly $550 in profit. A result of -$3.20 means you would expect to lose about $320 over those 100 bets.
EV as a proportion of your stake. This lets you compare opportunities regardless of bet size. An EV of +5.5% on a $100 bet is the same quality edge as +5.5% on a $500 bet. Serious bettors typically look for edges above 2-5% to make betting worthwhile after time costs and line movement.
The win probability baked into the sportsbook's line, including their margin (the vig). At -110, the implied probability is 52.38%. This is not what the book thinks the true probability is. It is a number inflated by their edge. The actual market consensus might be closer to 50%.
The minimum win percentage needed to not lose money at these odds over time. This equals the implied probability. At -110, you must win 52.38% of bets just to break even. At -130, the breakeven rate is 56.52%. Your true probability estimate needs to clear this threshold for any profit potential to exist.
Your estimated win probability minus the implied probability. An edge of +5% means your assessment is 5 percentage points more favorable than what the market implies. Positive edge combined with positive EV indicates a potentially profitable betting opportunity.
This is where most bettors struggle. The EV calculator is only as accurate as the probability you input. Here are the main approaches:
Sharp markets like Pinnacle and Circa build very thin vig into their lines. You can use their pricing as a starting approximation of true probability by removing their margin mathematically. If Pinnacle shows Team A at -108 and Team B at -108 (a balanced market), true probability is close to 50-50 for each side.
Compare odds across 5 to 10 sportsbooks, remove the vig from each, and average the no-vig probabilities. The consensus across a broad market is a reasonable proxy for true probability, though sharp money can still create systematic biases.
Build your own regression or simulation model using historical game data, team stats, injury reports, and situational factors. This produces true probability estimates independent of market pricing. Models require significant data science work and ongoing maintenance.
Tools like Juice use multiple AI models to analyze matchups and estimate win probabilities automatically. The app processes injury reports, recent performance trends, weather, pace-of-play mismatches, and dozens of other factors to produce a probability estimate without requiring you to build a model. For a full overview of how AI fits into modern betting research, read our guide on how AI helps estimate true probability.
Every standard -110 spread bet requires you to win 52.38% just to break even. Most casual bettors win around 48 to 50% of their bets, which means they are steadily losing money even when they win close to half their wagers. The vig is the silent tax that makes recreational betting a losing proposition by default.
| Odds | Breakeven Win Rate | Implied Probability |
|---|---|---|
| -110 | 52.38% | 52.38% |
| -120 | 54.55% | 54.55% |
| -150 | 60.00% | 60.00% |
| +100 (Even) | 50.00% | 50.00% |
| +120 | 45.45% | 45.45% |
| +150 | 40.00% | 40.00% |
| +200 | 33.33% | 33.33% |
To be profitable, you need to consistently find bets where your true probability exceeds the implied probability. That is what positive EV betting means in practice: finding systematic gaps between what you know and what the market prices in.
The single biggest conceptual shift required for profitable betting is accepting that EV is a long-run concept. A single +EV bet will lose roughly as often as its loss probability implies. A 10-game +EV run can still produce a losing record in the short term. What matters is accumulating enough +EV bets across a large enough sample for the math to play out.
Professional bettors think about results the same way a casino thinks about its house edge. Casinos do not worry about individual hands at a blackjack table because they know their edge will express itself over millions of transactions. A disciplined +EV bettor takes the same perspective: every good bet is a unit added to an edge that will eventually compound into profits.
Expected value tells you whether to bet. The Kelly Criterion tells you how much to bet. Once you have confirmed a bet is +EV using this calculator, use our Kelly Criterion Calculator to determine the optimal stake as a percentage of your bankroll.
Together, EV and Kelly form the complete mathematical framework for professional sports betting. Find +EV opportunities, size them with Kelly, track your results, and refine your probability estimation process over time.
Calculating EV for a parlay works the same way as a single-game bet, with one key addition: you multiply the individual probabilities together to get the combined probability of the parlay winning. For a 2-leg parlay where you estimate each leg at 55% probability:
The problem with most parlays is that sportsbooks do not give you true parlay odds. They shave each leg to increase their margin, and that vig compounds with every leg added. A 4-leg parlay where you genuinely have a 3% edge on each leg can still easily be -EV overall because the book's margin on each leg multiplies across all four. This is why most parlays are deeply negative EV despite occasional big payouts.
If you want to evaluate a parlay with this EV calculator, estimate your combined win probability (multiply each leg's probability together), then enter the actual parlay odds your sportsbook is offering. The calculator will show you whether the combined price is still +EV after accounting for the correlated vig.
Most serious bettors look for at least 2 to 5 percent EV. Any positive EV is theoretically profitable over a large enough sample, but edges under 1% are difficult to exploit reliably after accounting for line movement and timing. The higher the EV percentage, the stronger the edge.
Yes, absolutely. Positive EV is a long-run concept. A bet with +5% EV still loses close to half the time. Short losing streaks are completely normal even with a genuine edge. What positive EV guarantees (given a large enough sample) is that your results will trend profitable over time. A single session or even a month of results proves nothing about whether your process is sound.
The accuracy required depends on your edge size. If you're targeting 5% EV opportunities, being off by 2 percentage points on probability still likely keeps the bet positive. But if you're hunting thin 1-2% edges, a probability estimate that's off by even 1.5 percentage points can flip a +EV bet to -EV. The practical implication: focus on larger, more obvious edges when you're starting out. Thin edges require precise calibration that takes time and track record to develop.
No. Positive EV betting improves your long-run expectation but does not eliminate short-term variance. Even strong edges produce extended losing streaks due to normal statistical variance. EV is a long-run concept that requires a large sample size and consistent discipline to realize.
If your goal is long-term profitability, yes. Every -EV bet has a negative expected return regardless of how confident you feel about it in the moment. Disciplined +EV bettors pass on bets where their probability estimate does not clear the implied probability threshold, no matter how "good" the matchup looks.
EV is the expected value of a single bet at a given moment. ROI (return on investment) is the actual return you realized across your entire betting history. A positive EV strategy should produce positive ROI over a large enough sample, but short-term ROI can deviate significantly from expected EV due to variance.