Free, no signup, no promotions. Each one shows its formula and what it cannot tell you.
Odds Converter
Decimal, American, fractional and implied probability.
Vig & Hold Calculator
The margin in any market, and the fair prices without it.
Arbitrage Calculator
Stake split and return, with exchange commission handled.
Multi / Parlay Calculator
Combined odds, returns, and the real chance every leg lands.
No-Vig Fair Odds
Fair prices from a sharp market, then EV against them.
Expected Value Calculator
What a bet is worth on average, in percent and dollars.
Kelly Criterion Calculator
Optimal stake at full, half and quarter Kelly.
Bonus Bet Converter
Turn a bonus bet into cash you can withdraw.
For how the maths works rather than the arithmetic itself, see the guides.