What is expected value in betting?

Expected value (EV) is the average amount you expect to win or lose per bet if you repeated the same bet indefinitely. A +EV bet means you have a long-run edge; a -EV bet means the bookmaker profits over time.

How is EV calculated?

EV = (probability of winning × net profit) − (probability of losing × stake). For example, a 50% chance to win $110 on a $100 bet gives EV = (0.5 × 110) − (0.5 × 100) = $5.

What is a good EV for a bet?

Any positive EV is mathematically favorable. Professional bettors target edges of 2–5% or more. A very high edge (>10%) often indicates an error in your probability estimate rather than a genuine opportunity.

What is the break-even probability?

Break-even probability is the win probability at which EV equals zero. If your estimated win probability exceeds this number, the bet has positive EV; if it is lower, the bet has negative EV.

How do I convert American odds to decimal?

For positive American odds (e.g. +150): decimal = (odds / 100) + 1 = 2.50. For negative American odds (e.g. −110): decimal = (100 / |odds|) + 1 ≈ 1.909. This calculator handles the conversion automatically.

Should I always bet when EV is positive?

Positive EV is a necessary condition for a good bet, but you should also consider your bankroll size, odds variance, and the Kelly criterion to size your bets appropriately.

Expected Value Bet Calculator

Name: Expected Value Bet Calculator
Availability: InStock
Author: Nham Vu

Enter your probability estimate, payout odds, and stake to see whether a bet has positive or negative expected value.

Bet Parameters

Win Probability (%)

Your estimated chance the bet wins.

Odds Format

Decimal Odds

Decimal odds include your stake (e.g. 1.91 returns $1.91 per $1 bet).

Stake ($)

Expected Value (EV)

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per bet

Summary