Betting calculators
The arithmetic this site preaches, as tools you can point at your own numbers. Everything runs in your browser — nothing you type is sent anywhere.
Odds converter
Decimal, fractional and American formats, plus the implied probability every price is hiding.
Kelly criterion calculator
Turn a probability estimate and a price into a stake size — full, half and quarter Kelly, or an honest no-bet.
Accumulator calculator
Combined odds, returns and profit for up to twelve legs — with the implied chance of the ticket actually landing.
Poisson score matrix
Two expected-goals numbers in, a probability for every scoreline out — the engine room of most football models, as a toy.
Margin calculator
The odds of any market in, the bookmaker's overround and the fair, de-vigged probabilities out.
These calculators do the mechanical part. The judgement part — where a probability estimate comes from and whether it deserves your trust — is what the rest of the site is for: the how our predictions work, the live match probabilities, and the public track record that settles them.