EdgeLab
Sign in

Strategy guide · play money practice

What does EV mean in betting?

EV is short for expected value — the average result of a bet if you could place it a thousand times. It is the closest thing betting has to a scoreboard for decisions rather than outcomes: a good bet can lose and a terrible bet can win, but over a season only expected value decides where you end up.

Practise with $10,000 play money

The expected value formula

Expected value compares what you win when you're right against what you lose when you're wrong, weighted by how often each happens:

EV = (win probability x profit) - (loss probability x stake)

Say a team is priced at +150 and, after your own research, you think they win 45% of the time. A $100 bet returns $150 profit when it hits:

(0.45 x $150) - (0.55 x $100)
= $67.50 - $55.00
= +$12.50 per $100 staked

That is a positive EV bet. It still loses more often than it wins — 55% of the time — which is exactly why judging your betting by last weekend's results tells you almost nothing.

Implied probability: what the odds already assume

Before you can say an edge exists, you need the probability the price itself implies. With American odds:

  • Negative odds (favourites)

    odds / (odds + 100). A -150 favourite: 150 / 250 = 60% implied.

  • Positive odds (underdogs)

    100 / (odds + 100). A +150 underdog: 100 / 250 = 40% implied.

In the example above the price implied 40% and you estimated 45%. That five-point gap is your claimed edge — and the whole game is being honest about whether your 45% is better information or just optimism.

Why the vig makes most bets negative

Add the implied probabilities on both sides of a typical -110 / -110 market and you get 52.4% + 52.4% = 104.8%. That extra 4.8% is the sportsbook's margin, the vig. It is why a coin-flip bettor at -110 loses money over time: you risk $110 to win $100, so you need to win about 52.4% of your bets just to break even.

To find the market's true estimate, divide each side by the total. Here: 52.4 / 104.8 = 50% each. Positive EV betting is the search for prices where your estimate beats that vig-free number — not merely the raw odds.

Turning EV into actual decisions

  1. 1

    Estimate the probability before you look at the price

    Anchoring on the odds turns your 'independent' read into an echo of the market. Write your number down first.

  2. 2

    Convert the price to implied probability

    Use the two formulas above. If the price implies more than your estimate, there is no edge — pass, no matter how much you like the team.

  3. 3

    Remove the vig before you celebrate

    A two-point 'edge' on a market carrying 4.8% juice is not an edge at all.

  4. 4

    Stake by bankroll rules, not by conviction

    Positive EV only pays off if you survive the variance. Flat one-unit stakes are how you get there.

  5. 5

    Grade the decision, not the result

    Log your estimate and the price for every bet. After 100 bets you can check whether your probabilities were calibrated — that is the real test.

No calculation guarantees a winning bet. Expected value is a way to make better decisions with uncertain information, not a way to predict games.

Practise EV without risking money

EdgeLab is a free simulator: $10,000 in play money, a realistic multi-league board, and an AI coach that grades each bet against the price you took and the estimate you gave. Nothing is deposited and nothing is paid out — it exists so you can run a few hundred practice bets and see whether your read is actually worth anything before it costs you.

Start practising freeRead the bankroll guide