What counts as a good EV?

Any positive EV means the bet is priced in your favor at your probability. Small edges, in the low single digits of a percent, are typical for serious bettors. The number is only as reliable as the win probability you put in.

Where does my win probability come from?

From your own model or read on the game. If you do not have one, paste the other side's price and let the calculator use the fair no-vig probability as a neutral estimate.

Is EV the same as guaranteed profit?

No. EV is a long-run average. Any single bet still wins or loses. A positive EV only means that, repeated many times at that true probability, the bet would come out ahead on average.

Why is EV negative when I win most of the time?

A high win rate at short odds can still be negative EV if the price does not pay enough for the risk. EV weighs the payout against the probability, not just how often the bet wins.

Free calculator

Expected value calculator

Enter a price and your estimated win probability to see the bet's expected value. You get EV per $100, EV as a percentage, and your edge over the price's implied probability.

Price (your bet)

Win probability from

Your win probability

EV per $100

+$5.00

EV %

+5.00%

Edge vs implied

+2.62%

Implied probability

52.38%

from the price

For information only. Not betting advice.

How it works

Expected value is the average result of a bet if you could place it many times. Multiply your win probability by the decimal odds, then subtract 1. A positive number means the bet pays more than its true risk at your probability; a negative number means it does not.

EV per $100 is that figure times 100. The edge is your win probability minus the probability the price implies. If you think a side wins more often than the price suggests, both the edge and the EV are positive.

If you are not sure of your own probability, paste the price of the other side of the market. The calculator removes the margin from the two prices and uses the fair no-vig probability as the win probability.

Worked example

A bet at -110 with a 55% win probability has decimal odds of 1.9091. The EV per dollar is 0.55 × 1.9091 − 1 = 0.05, which is +5.00%, or +$5.00 per $100. The price implies 52.38%, so the edge is 55.00% − 52.38% = +2.62%.

Questions

What counts as a good EV?: Any positive EV means the bet is priced in your favor at your probability. Small edges, in the low single digits of a percent, are typical for serious bettors. The number is only as reliable as the win probability you put in.
Where does my win probability come from?: From your own model or read on the game. If you do not have one, paste the other side's price and let the calculator use the fair no-vig probability as a neutral estimate.
Is EV the same as guaranteed profit?: No. EV is a long-run average. Any single bet still wins or loses. A positive EV only means that, repeated many times at that true probability, the bet would come out ahead on average.
Why is EV negative when I win most of the time?: A high win rate at short odds can still be negative EV if the price does not pay enough for the risk. EV weighs the payout against the probability, not just how often the bet wins.

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