If value betting tells you what to look for, Expected Value (EV) tells you how much that opportunity is worth.
Expected Value is one of the most important concepts in probability and betting. It measures the average amount you can expect to win or lose if the same bet were placed repeatedly under identical conditions.
Rather than focusing on the outcome of a single bet, EV evaluates the quality of the betting decision itself.
Expected Value (EV) is the average profit or loss you would expect if the same bet were repeated an infinite number of times.
A bet can have one of two types of expected value:
Short-term results may differ because of randomness, but over hundreds or thousands of bets, actual results tend to move towards the expected value.
The standard formula for calculating EV is:
EV = (Pwin × Profit) − (Plose × Stake)
Where:
This formula combines both possible outcomes into a single average result.
Suppose you place the following bet:
Using the formula:
EV = (0.45 × £150) − (0.55 × £100)
EV = £67.50 − £55.00 = +£12.50
This means that every time you place this £100 bet, you expect to earn an average profit of £12.50 over the long run.
The actual result of any individual bet will still be either a win or a loss, but the average outcome across many identical bets is positive.
Now consider the same bet, but assume your estimated probability of winning is only 35%.
The calculation becomes:
EV = (0.35 × £150) − (0.65 × £100)
EV = £52.50 − £65.00 = −£12.50
The advertised odds have not changed, but your assessment of the true probability has.
This bet now has a negative expected value, meaning you would lose an average of £12.50 for every £100 staked if the same opportunity occurred repeatedly.
Many professional bettors express EV as a percentage of the stake because it makes bets of different sizes easier to compare.
The formula is:
EV% = (EV ÷ Stake) × 100
Using the previous positive example:
(£12.50 ÷ £100) × 100 = +12.5%
This means the bet has an expected return of 12.5% on every pound staked.
Expressing EV as a percentage allows bettors to compare opportunities regardless of stake size.
A positive EV does not guarantee an easy profit.
In real betting markets, genuinely high-EV opportunities are uncommon because bookmakers adjust their prices quickly.
As a general guide:
Small positive edges may appear insignificant, but when repeated consistently over hundreds or thousands of bets, they can produce substantial long-term profits.
Expected Value shifts your focus away from individual results and towards decision quality.
A positive EV bet can lose today, while a negative EV bet can win today.
What matters is whether your decisions are mathematically profitable over the long run.
This mindset helps bettors avoid judging their performance based solely on short-term outcomes and instead evaluate whether they consistently identify value.
Expected Value (EV) measures the average profit or loss you can expect from a bet over the long run. Positive EV bets are mathematically profitable because your estimated probability is greater than the probability implied by the bookmaker's odds, while negative EV bets lose money on average. Successful bettors focus on consistently making positive EV decisions, knowing that long-term results will eventually reflect the quality of those decisions.
