Betting maths calculators
Free, instant calculators for the maths behind disciplined betting — staking, value and variance. No sign-up needed. Educational tools only: OutlayHQ takes no bets and holds no funds.
Betting maths
Kelly CriterionWork out how much to stake from your edge using full, half or quarter Kelly.DutchingSplit one stake across several runners so whichever wins returns the same.Odds ConverterConvert between decimal, fractional, American and Malay odds — and implied probability.Betfair CommissionSee your real return and break-even strike rate after exchange commission.Closing-Line ValueCompare the odds you took to the closing price to measure your edge.Each-WaySee your return if it wins, places only, or loses — with the place terms you choose.AccumulatorCompound a stake across up to 8 legs to see the final return and profit.Losing StreakYour Expected Losing Sequence — how long a losing run is normal, and the bankroll that survives it.Staking Plan ComparisonRun the same bets through different staking plans and see which grows the bank without busting it.Multi & SGM MarginSee what your multi really costs — the per-leg margin compounds across every leg.Overround / MarginEnter a market’s prices to get the book percentage, the margin, and the fair odds.
Staking plans
Every classic staking plan, free — each with a live mini-simulator running the real engine. All free with an account in Proving Ground too.
Level StakesBet the same flat amount every time — the simplest, hardest-to-bust staking plan.Percentage StakingStake a fixed share of your current bank, so stakes grow on wins and shrink on losses.D'AlembertUp one unit after a loss, down one after a win — a gentle progression.FibonacciStep up the 1-1-2-3-5 sequence on losses, back two on a win.LabouchèreStake the first + last of a number line; cross off on wins, add on losses.MartingaleDouble your stake after every loss, reset on a win — the highest-risk progression. ⚠Stop-at-a-WinnerChase a small target sized to your expected losing run; one winner banks it.Square RootWhen in profit, add the square root of your profit to a flat unit.1-3-2-6Ride the 1-3-2-6 sequence on wins; any loss or completing it resets to 1.ParlayLet the full return ride for a set run of wins, then bank; a loss resets.Up X / Down YUp X units after a win, down Y after a loss — a tunable positive progression.Target ProfitStake exactly enough to recoup the shortfall to a fixed target at the odds. ⚠RetirementSpread a unit target plus the run’s losses over a fixed divisor.6-Point DivisorA six-unit target whose divisor counts down with each winner.Step Percentage (Bookies Bank)A calmer percentage plan — the unit only re-steps after a ±10% bank move.
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