What Is Expected Value (EV) in Betting?

The short answer

Expected value (EV) is how much you'd win or lose on average per bet if you could place the same bet thousands of times. A bet with positive EV (+EV) pays more than the risk is worth, so it makes money over time. A bet with negative EV (-EV) pays less, so it loses money over time, even if it wins today.

The formula for decimal odds is simple:

EV = (true probability × decimal odds) − 1

If a team has a 45% chance of winning and you can back them at 2.40, the EV is (0.45 × 2.40) − 1 = +8%. On average, every £10 you bet like that is worth +£0.80.

What expected value actually means

Any single bet either wins or loses. EV ignores that and asks a different question: if this exact bet were placed again and again, what would the average result be?

Take the bet above. At 2.40, a £10 winner pays £14 profit. A loser costs £10. With a 45% chance of winning:

• 45% of the time you win £14: 0.45 × £14 = £6.30
• 55% of the time you lose £10: 0.55 × £10 = £5.50
• Average result per bet: £6.30 − £5.50 = +£0.80, or +8%

You'll never see +£0.80 on a single bet. You'll see +£14 or −£10. But over hundreds of bets like it, your results will drift towards that +8%.

How to calculate EV on any bet

There are two ways to write it, and they give the same answer.

As a percentage: EV = (true probability × decimal odds) − 1

In money: EV = (probability of winning × profit if it wins) − (probability of losing × stake)

A few quick examples, all with a true probability of 45%:

The break-even price is 1 divided by the true probability: 1 ÷ 0.45 = 2.22. Anything above 2.22 is +EV. Anything below is −EV. The match is exactly the same in every row. Only the price changes.

Where the true probability comes from

The formula is easy. The hard part is the true probability, because nobody knows the exact chance of a football team winning.

You can build your own model, but most bettors use a simpler benchmark: the odds at a sharp bookmaker like Pinnacle, with the margin removed. Pinnacle takes big bets from winning players and moves its prices on their money, so its odds are about as close to the true chance as you'll find. Our guide to Pinnacle closing odds explains why.

Here's how it works in practice. Say Pinnacle prices a tennis match at 1.95 for each player. Remove the margin and each player has a 50% chance, so the fair odds are 2.00. If a soft bookmaker offers 2.08 on one of them:

EV = (0.50 × 2.08) − 1 = +4%

For markets with three outcomes, or prices that aren't level, removing the margin takes a little more maths. The free no-vig odds calculator does it for you.

Why most bets are −EV

Bookmakers build a margin into every price, so most bets are −EV before you start. On a coin toss, the fair odds are 2.00 on each side. A bookmaker might offer 1.91 on both:

EV = (0.50 × 1.91) − 1 = −4.5%

That 4.5% is the bookmaker's edge, and it's why most bettors lose over time. To bet +EV, you need to find prices that are higher than the true chance, which usually means finding a soft bookmaker that's out of line with the sharp price. That's what value betting is.

EV and results: why +EV bets still lose

A +8% bet loses 55% of the time. A run of +EV bets can easily lose money for weeks. EV describes the long run, not the next bet, so you need volume before your results start to reflect it.

In our study of 25,954 value bets tracked by OddsHub users, weekly returns swung from −2.6% to +4.4%, even though the bets had a positive edge throughout. Over the full sample they returned +2.8%.

EV v closing line value (CLV)

EV is your estimate of a bet's value at the moment you place it. Closing line value (CLV) is the check that comes later: how your odds compare with the final, most accurate price before the event starts.

The two usually agree, but not perfectly. Prices keep moving after you bet, and sometimes the market moves against you. In the same study, value bets had an average EV of +6.7% when they were placed, and an average CLV of +4.9% at the close. Some of the edge was lost as the markets settled, but most of it held.

That's why serious bettors track both. EV tells you whether a bet looks good when you take it. CLV tells you whether it really was.

How much EV is enough?

In theory, any +EV bet is worth taking. In practice, very thin edges are fragile. The price might move before your bet goes through, your estimate of the true probability might be slightly off, and the margin for error is tiny.

The value bets study shows this clearly:

Bets under 2% EV barely beat the close and lost a little. From 2% upwards, every group was profitable. A sensible rule for most bettors is to look for 2% EV or more.

Find +EV bets for free

Working out EV by hand means checking the sharp price, removing the margin and comparing it with every bookmaker you use, before the odds move. The free value bets page on OddsHub does that for you, comparing 490+ bookmakers with Pinnacle's fair odds and showing the EV on every bet, for value bets up to 3% EV on a 15-minute delay.

For real-time value bets at any EV, plus automatic EV and CLV tracking on every bet you take, try the OddsHub Terminal.