Expected Value (EV) Calculator
Calculate the Expected Value of any sports bet in one click. Enter decimal odds and your estimate of the true probability — get instant EV%, your edge over the bookmaker, and expected profit per stake.
What is Expected Value (EV) in betting?
Expected Value (EV) is the average profit (or loss) you'd make per bet if you placed the same bet thousands of times. It's the single most important number in sports betting — it tells you whether a bet has positive long-term value or whether the bookmaker has the edge.
The formula is simple:
If EV > 0, you have a value bet — over many bets, you make money. If EV < 0, you lose money long-term, regardless of whether this particular bet wins.
Example: Calculating EV step by step
Let's say the bookmaker offers 2.10 on Team A to win. You estimate Team A's true probability of winning at 52%:
- Convert probability to decimal:
52% = 0.52 - Multiply odds × probability:
2.10 × 0.52 = 1.092 - Subtract 1:
1.092 − 1 = 0.092 = +9.2%
Result: +9.2% EV. On a $100 stake, your expected profit per bet is $9.20. Over 1,000 such bets, you'd profit roughly $9,200 — minus variance.
EV examples across markets
| Sport | Bet | Odds | True P | EV | Verdict |
|---|---|---|---|---|---|
| Soccer | Liverpool ML | 1.85 | 58% | +7.30% | Value |
| NBA | Celtics ML | 2.10 | 52% | +9.20% | Strong value |
| Tennis | Djokovic ML | 1.62 | 65% | +5.30% | Value |
| EPL Draw | Spurs vs Arsenal Draw | 3.20 | 30% | −4.00% | No bet |
| Soccer Total | Over 2.5 | 1.95 | 55% | +7.25% | Value |
| NFL Spread | Chiefs −3.5 | 1.91 | 50% | −4.50% | Bookmaker edge |
Notice: not every bet has positive EV. In fact, most don't — that's how bookmakers make money. EV betting works by selecting only the small percentage of bets that are mispriced in your favor.
How to estimate the true probability
The hardest part of EV betting is not the calculation — it's getting an accurate probability estimate. Three proven approaches:
1. No-vig method (recommended for beginners)
Take the best odds available across all bookmakers for each outcome. Remove the margin proportionally. The result is the market's no-vig fair probability. This is the consensus of all sharp bookmakers and is usually within ±1% of the true probability.
2. Sharp book pivot
Use Pinnacle, Betfair Exchange, or Smarkets odds as your baseline. These books are run by sharp traders, take large limits, and barely move on public action. Their odds (devigged) approximate the true probability better than any model an individual bettor can build.
3. Your own model
For specific sports/markets (NBA totals, soccer xG, tennis surface adjustments), a custom Poisson, Elo, or ML model can beat the market. This is how syndicates extract edge — but it requires data, code, and validation.
Most casual value bettors should use approach #1. EVBets automates this across 94 bookmakers and 88 sports.
EV vs implied probability — what's the difference?
Implied probability is what the bookmaker's odds tell you: 1 / decimal_odds. At 2.10 odds, implied probability = 1 / 2.10 = 47.6%.
True probability is your estimate of the real chance the outcome happens.
EV is positive when your true probability is higher than the implied probability — meaning the bookmaker has under-priced this outcome. The bigger the gap, the higher the EV.
Quick mental shortcut: edge = true_prob − implied_prob. If your edge is > 0, the bet has positive EV.
EV betting strategy — common pitfalls
- Variance is brutal. A +5% EV portfolio can have losing months. You need 500+ bets to see EV converge to actual results.
- Stake sizing matters. Never bet 100% of your bankroll on one "huge" +EV opportunity. Use the Kelly Criterion — typically Quarter Kelly (25% of full Kelly) for safety.
- Bookmaker limits. Soft books (DraftKings, FanDuel, Bet365) will cut you to $5 stakes within months if you only place +EV bets. Spread action across multiple books and use exchanges (Betfair, Smarkets) for sharp-priced bets.
- Don't chase >20% EV. Almost always a stale price, palp error, or limit-down market — not a real edge. Verify the line before betting.
- Closing line value (CLV). The strongest proof you're a +EV bettor is beating the closing line. Track your CLV — if you consistently bet at better odds than the closing line, you're a winner regardless of short-term results.
Frequently asked questions
What's a good EV percentage for a value bet?
Sharp bettors target EV above +2%. Below +1% the edge often gets erased by margin variance and bookmaker limits. Above +20% is usually a data error — verify the odds and your probability estimate before betting.
How many bets do I need to see EV converge?
At least 500 bets, ideally 1,000+. Short-term variance is huge — a +5% EV portfolio can be down after 100 bets and still be profitable long-term. Track every bet, calculate your average EV, and compare with actual ROI over time.
Does EV work for accumulators/parlays?
Mathematically, yes — multiply individual probabilities, multiply odds. But practically, parlays compound bookmaker margin: a 4-leg parlay can have 15-25% margin baked in vs 4-7% per single. Stick to singles for serious EV betting.
Is positive EV betting legal?
Yes — placing bets with positive expected value is just betting smart. It's legal everywhere sports betting itself is legal. Some bookmakers limit or close winning accounts (which is also legal on their side), so professional bettors spread action across many books and use exchanges.
EV calculator vs Kelly calculator — which do I need?
Both. EV tells you whether to bet (positive EV → yes). Kelly tells you how much to bet (optimal stake fraction). EV first, Kelly second. Use the Kelly calculator after confirming positive EV here.
Next steps
- Find real +EV bets right now: EVBets live value bets (updated every 60 seconds across 94 bookmakers)
- Remove bookmaker margin from odds: No-Vig Calculator
- Size your stake optimally: Kelly Criterion Calculator
- Convert between American/decimal/fractional: Odds Converter
- Multi-leg parlays: Parlay Calculator