Expected Value (EV) Calculator
Enter the odds being offered and your estimated true probability. See if a bet is +EV and how much edge you have.
Enter odds and your estimated probability to see the results.
What is Expected Value (EV)?
Expected Value is the average amount you expect to win (or lose) per bet if you placed it an infinite number of times. EV is the foundation of professional betting and trading.
A +EV bet has a positive expected value in your favor over the long run. A -EV bet loses money over time, no matter how many times you place it.
How to Calculate EV
The fundamental EV formula is:
For a typical sports bet with -110 odds and a 55% true probability:
EV = (0.55 × $0.91) − (0.45 × $1.00) = $0.50 − $0.45 = +$0.05 per $1 bet
This means over 100 such bets, you'd expect to profit ~$5 per $100 wagered (a +5% ROI).
What Makes a Bet +EV?
A bet is +EV when your estimated probability of winning is higher than the implied probability of the odds being offered. The gap between these two probabilities is your edge.
For example, if you estimate 55% and the odds imply 52%, your edge is 3%. Over hundreds of bets with a 3% edge, you'll be profitable in expectation.
This edge is what separates professional bettors from casual gamblers. Pros hunt for small edges (+1–5%) and rely on volume to compound returns.
Why EV Matters More Than Individual Outcomes
A +EV bet can still lose. A -EV bet can still win. That's variance — randomness in the short term.
But over hundreds or thousands of bets, variance smooths out, and EV determines whether you make or lose money. This is why professional bettors obsess over process, not results. They focus on identifying +EV opportunities and letting the math work.
One losing bet doesn't invalidate your edge. One winning bet doesn't prove your edge exists. Only over time does expected value reveal itself.
Who Uses EV Calculations?
- Sports bettors hunting for value in NFL, NBA, college sports, soccer, etc.
- Prediction market traders on Polymarket, Kalshi, and other platforms
- Poker players evaluating every decision in real-time
- Professional gamblers and quant traders managing portfolios of bets
- Anyone making decisions under uncertainty who wants to optimize long-term returns
EV and the World at Odds Podcast
We use EV thinking on the show to evaluate everything from sports bets to political predictions. It's not about being right on any single bet — it's about making decisions that have positive expected value over time.
When we debate whether a bet is worth taking, we're asking: "Is the probability we assign higher than the market is implying?" If yes, it's worth considering. If no, we move on. That discipline is what separates professionals from the crowd.