Expected value calculator
Updated August 2026
The expected value formula, running live: what a bet is worth on average, before luck has its say.
+$5
expected value per bet
Positive EV: over many bets like this one, the math is on your side.
The expected value formula
EV = (chance you win × what you'd profit) − (chance you lose × what you'd stake). At 55% to win $90.91 on a $100 stake at −110: 0.55 × 90.91 − 0.45 × 100 = +$5. Run that bet forever and you average five dollars a pop; run its 50% cousin and you average a loss. The formula is the entire difference between betting and investing in edges.
Break-even: the other useful number
Every price implies a chance you must beat: at −110 you need 52.4% just to tread water, the gap above 50% is the vigtalking. If your honest estimate doesn't clear the break-even row, the rest of the calculator is just telling you how much the lesson costs.
Quick answers
What is the expected value formula?+
EV = (win chance × profit if you win) − (lose chance × stake). It's the average result of the bet if you could run it a thousand times, one number that says whether the price is on your side.
What's a good EV?+
Anything reliably above zero is gold, professionals grind edges of 2–5% per bet. The catch is the word reliably: a positive EV is only as real as the win probability you fed in.
Why did my positive-EV bet lose?+
Because EV describes the long run, not tonight. A +EV bet losing is normal; judging the decision by one result is outcome bias, graded in our glossary.