Understand your bet before you place it.
Calculate payouts, convert odds and see the real probability behind singles, accumulators and parlays. Free, private and instant.
For information and mathematical education only. No result is guaranteed. 18+ where applicable.
Quick payout calculator
Stake plus profit, paid if the bet wins.
What you keep after your stake is returned.
1 in 2.5 — the chance built into this price, margin included.
Parlay Reality Check
Add 2 to 20 selections and see what the combined price actually implies: the chance everything lands, the chance at least one leg fails, and how much the single riskiest selection is costing you. Share the result with a link that rebuilds the exact calculation.
Selections (3/20)
Every active price multiplied together.
Stake plus profit if every selection wins.
Payout minus your stake.
1 in 7.0
The chance this bet does not pay out.
Each added selection multiplies the ways this bet can fail.
Drop the riskiest selection
Removing the longest price (2.10) changes the combined odds to 3.32 and lifts the implied chance from 14.32% to 30.08%.
Every added leg multiplies the ways this bet can fail. Expect long losing runs between wins.
This assumes independent outcomes. Selections from the same match or the same team are correlated, so the real chance can be meaningfully different — usually worse for you than the number above, sometimes better. Bookmaker margin is already inside each price, so the combined implied probability is higher than the true combined chance.
The link contains your selections, so anyone who opens it sees the same calculation. No account and no saved data.
Every calculator
Ten tools, each on its own page with the formula, worked examples and the mistakes people usually make.
Bet Payout Calculator
Work out exactly what a single bet returns and what profit is left after your stake.
OpenParlay Calculator
Multiply 2–20 selections into one combined price and see how small the real chance becomes.
OpenAccumulator Calculator
The same multi-selection maths in UK and European terms, including voided legs.
OpenOdds Converter
Move between decimal, American and fractional odds without a lookup table.
OpenImplied Probability Calculator
Turn any price into the percentage chance the bookmaker's odds represent.
OpenBookmaker Margin Calculator
Measure the overround baked into a market and see the fair odds without it.
OpenHedge Calculator
Find the stake on the opposing outcome that equalises profit or recovers your stake.
OpenKelly Criterion Calculator
Size a stake from your own probability estimate — and see when the maths says zero.
OpenEach-Way Calculator
Split a stake across win and place parts and see the return for every finishing result.
OpenBet Tracker
Log bets in your own browser and see real ROI, win rate and closing line value.
Open
Why use bet.ing
Instant, in-browser maths
Every result is computed locally as you type. There is no server round-trip and no waiting.
Decimal, American and fractional
Mix notations inside the same calculation. bet.ing converts everything to decimal odds internally.
No registration, nothing uploaded
Your stakes, selections and tracker entries stay in your browser. We never see them.
Every formula shown
Each calculator prints the formula it used plus worked examples, so you can verify the number yourself.
Built mobile-first
Large tap targets, readable numbers and a layout that works from a 360px phone upwards.
Risk explained, never promised away
No tips, no picks, no guaranteed-win claims. Just the probability and variance behind a price.
Learn the maths
Plain-English guides with the same formulas the calculators use.
- How Betting Odds WorkWhat a price actually represents, and why it is not a prediction.
- Decimal vs American vs Fractional OddsThree notations for the same number, with a conversion table.
- What Is Implied Probability?Turning a price into a percentage — and what the percentage leaves out.
- Why Parlays Are Hard to WinHow multiplication and margin compound against multi-leg bets.
- How Bookmaker Margin WorksOverround, the fair book, and how to compare two prices properly.
- How to Track Betting ROIThe right denominator, sample size, and why win rate alone misleads.
- Responsible Bankroll ManagementFixed staking, drawdowns, and setting limits before you need them.
Bet responsibly
These tools exist to make the maths visible, not to encourage more betting. The house edge is built into every price you see, which is why the implied probabilities on this site always add up to more than 100%.