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Expected Value Calculator

A bet's expected value is EV% = (fair probability × decimal odds − 1) × 100 — positive when the price pays more than the outcome's true chance demands, negative when it pays less.

Expected value+10.0%+$10.00 expected per $100.00 bet
Outcomes
Wins (50.0% fair)
+$120.00
Loses (50.0% fair)
−$100.00
Fair odds at that probability-100
Full-Kelly fraction8.33%
Show the math
EV% = (p × decimal − 1) × 100(0.5000 × 2.2000 − 1) × 100 = 10.00%

The Scout’s Notebook

How do you calculate a bet's expected value?

A bet's expected value is EV% = (fair probability × decimal odds − 1) × 100 — positive when the price pays more than the outcome's true chance demands, negative when it pays less.

How it works & common questions

The outcome bars make the asymmetry tangible: what you win at the fair rate, what you lose the rest of the time, and whether the balance favors you.

How it works

  1. Enter your price and stake. The odds you can actually bet right now.
  2. Set the fair probability. Type it, or devig a sharp reference market with the power method.
  3. Read the verdict. EV% and expected dollars per bet — negative means the math says pass.

What is a good EV percentage on a bet?

Consistently finding +2% to +5% EV is strong in liquid markets, and anything above that deserves skepticism about the fair probability behind it. The EV is only as honest as the probability you feed it.

Learn more: Expected Value & De-Vigging (guide)

Dynatyze Betting is analytics and education for people 21 and over. It is not a sportsbook: no wager is ever placed on Dynatyze — the tools help you find and price the best available bet elsewhere. If gambling stops being fun, help is free and confidential at 1-800-GAMBLER.