Calculator
+EV Calculator — Compute True Expected Value
Expected value (EV) tells you whether a bet is profitable on average. If you estimate a team has a 55% chance of winning but the book only prices them at 52%, you have an edge. Enter your true probability and the offered odds to see your EV.
A positive EV% means the bet is profitable on average at that stake. Bet +EV consistently and the math works in your favor over time.
Size this bet with Kelly →Your estimate of the outcome's real chance of happening (not the book's implied odds)
The price the sportsbook is offering right now
How this works
Formula
EV = (p_true × profit_if_win) - ((1 - p_true) × stake)
Worked example
True prob 55%, price +120 (profit $120 on $100): EV = 0.55 × 120 - 0.45 × 100 = +$21 on $100, or +21%.
FAQ
What is positive EV (+EV) betting?
+EV means the price you got is better than the true probability of the outcome. Bet +EV consistently and you profit long-term.
How do I know the 'true' probability?
The best proxy is the sharp consensus — Pinnacle, Betfair Exchange, Kalshi, Polymarket — devigged. Parlae does this automatically.
Is 1% EV enough to bet?
Yes if your edge is real. The risk: small edges are easily wiped out by mis-estimated probability. Most pros target 2%+ on majors.
Does EV account for limits or account closures?
Pure EV math does not. Practical EV must factor in book-tolerance — if you're a +EV bettor a book will limit you.
How does this differ from Kelly?
EV tells you whether to bet. Kelly tells you how much. Use both: only bet +EV plays, and size them with Kelly.