What does expected value mean?
It is the probability-weighted average net result. This calculator assumes one win payout and one full-loss outcome.
Betting & casino math
Expected value
calculator.
See the average net result implied by a wager’s price and your estimate of its chance to win.
01 / Input
Describe the wager
$USD
AMERICAN
Try a common line
%
Enter your estimate of the true chance to win, not the odds’ break-even probability.
Expected value formula
EV = 45.00% × $140.00 − 55.00% × $100.00 = +$8.00
Assumes a win earns the listed profit and a loss loses the full stake. Pushes, fees, and taxes are not included.
02 / Readout
Here’s the average on paper
Expected net value per wager
+$8.00
0% win estimate100%
EV per $100 staked+$8.00
Return on stake+8.00%
Break-even probability41.67%
Your estimate above break-even+3.33 pp
Input price+140
Stake amount$100.00
Profit if it wins$140.00
Loss if it loses$100.00
Total return if it wins$240.00
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With these inputs, the average net result is +$8.00 per wager over many comparable outcomes. A single result can still lose.
Read it correctly
An average, not
a forecast.
Expected value weights each possible net result by its probability. It does not say what the next bet, spin, or round will do.
+
Positive EV
Your estimate is above the price’s break-even rate.
+140 · 45% estimate → +$8 per $100−
Negative EV
The price and estimate average to a loss.
At break-even odds, EV is $0Common questions
Use the average with context
The calculation follows your inputs. It cannot verify your probability estimate or predict an individual outcome.
Does positive EV mean I’ll win?
No. It describes an average over many comparable outcomes if your probability estimate is accurate. Any individual wager can lose.
Can I use this for casino games?
Yes for a wager with one win payout and one loss amount, such as a roulette color bet. For games with several payouts, each outcome needs its own probability and net result.
What if my estimate equals break-even?
The expected value is zero before fees or other costs. That is the probability needed to break even at the entered price.
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