Free betting calculators

Betting tools that tell you the truth

Free calculators built on the same math we use to audit odds and tipsters. No sign-up, everything runs in your browser.

Fair odds calculator (devig)

Paste a 1X2 market and see the margin-free fair odds and true implied probabilities.

Method: power devig — the same one this site has used since 18 July 2026, calibrated on 35,454 matches. It solves for the exponent that makes the probabilities sum to 1, which removes proportionally more margin from longshots. The proportional column is shown for comparison only: it spreads the margin evenly and therefore overvalues outsiders — see Longshot bias for why.

Accumulator cost calculator

See how much house edge your acca really carries as you add legs.

Every leg multiplies the bookmaker's margin. Full arithmetic in our article: Accumulator cost calculator.

Break-even win rate calculator

At your average odds, how often must you win just to not lose money?

One divided by the odds. Any advertised win rate below this number loses money at these odds — see Why win rate misleads.

CLV calculator

Compare the odds you took with the closing odds to see if you beat the market.

Why the closing line is the benchmark that can't be faked: Closing Line Value (CLV).

Bet Slip Auditor

Your whole accumulator, audited: fair price, hidden compounded margin, and the leg that hurts you most.

Open the auditor →

Audit my tipster

Paste a tipster's record — or your own betting history — and get the honest verdict: real ROI, the break-even bar, and how likely the whole record is plain luck.

Audit this record →

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