Value Bet Calculator
Work out the expected value (EV) of a bet from your own estimated win probability compared with the odds on offer.
Your own judgement of the chance the outcome happens — not the probability the odds imply. The calculator is only as good as your own estimate.
Enter your stake, the odds and your estimated win probability to see the expected value.
This calculation relies entirely on your own estimate of the win probability and is no guarantee of profit. A positive expected value only shows up over many repeated bets — any single bet can still lose.
A value bet calculator helps you judge whether a bet is profitable long-term — not by gut feel, but by the math behind your own probability estimate compared with the odds you're being offered. Enter your stake, the odds and your assessed win chance, and the calculator instantly works out the expected value (EV), your edge and the break-even line.
How the value bet calculator works
A value bet exists when your own estimate of the win probability is higher than the probability the odds imply. The odds set the bookmaker's break-even line (1 / odds) — if your estimate beats that line, the bet has a positive expected value, whether or not this particular bet actually wins.
EV per unit staked = p × (odds − 1) − (1 − p)
p is your estimated win probability (0–1) and odds are decimal odds. EV converts to currency by multiplying by your stake, and to a percentage by multiplying by 100. Your edge is the gap between your probability and the odds' break-even line (1/odds) — the bigger the edge, the more profitable the bet is by your own assessment.
Worked example
Say you stake 100 at odds of 2.50 on an outcome you judge to have a 50% chance of happening. The odds' implied break-even probability is 1/2.50 = 40%, so your assessed edge is 10 percentage points.
The expected value works out to 0.50 × (2.50 − 1) − 0.50 = 0.25 per unit staked, i.e. 25% of the stake. On a 100 stake that's an EV of +25 — a positive expected value by your estimate, provided that estimate holds up over time.
Frequently asked questions
What is a value bet?
A value bet is a bet where your own estimate of the win probability is higher than the probability the bookmaker's odds imply. That means the bet has a positive expected value (EV) long-run, even though any single bet can still lose — EV is an average over many repeated bets, not a guarantee for this one.
How do I know if my probability estimate is accurate?
You never know for certain — the calculator only tells you what EV works out to GIVEN your estimate. The better your own analysis of the outcome (form, injuries, statistics, line shopping across bookmakers), the more reliable the EV figure becomes. If you systematically overestimate your win chances, the calculator will show value bets that don't actually exist.
Is a positive EV enough to turn a profit over time?
A positive EV is necessary but not sufficient on its own — you also need enough bets for variance to even out, and a stake size that doesn't risk your whole bankroll along the way (see the Kelly calculator for that). A single value bet can still lose; it's the sum of many value bets over time that produces the expected profit.
