Free Bet Conversion Calculator
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How to use the free bet conversion calculator
This is for a free or bonus bet where the stake is not returned, the usual kind, laid off on a betting exchange to lock in cash. Enter the free bet amount, the bookmaker back odds, the exchange lay odds and the exchange commission. The calculator shows the lay stake to place, the guaranteed profit you keep whichever way the event goes, and the conversion rate, which is how much of the free bet you turn into real money. Decimal is the format exchanges use by default.
The terms in short
- Stake not returned (SNR): a free bet that pays only the winnings, not the stake, so its cash value is below face value.
- Back odds: the bookmaker odds you place the free bet at.
- Lay odds: the exchange odds you bet against the same outcome at.
- Commission: the cut the exchange takes from a winning lay.
- Conversion: the guaranteed profit as a percentage of the free bet's face value.
How the lay is calculated
The lay stake is set so both outcomes leave the same cash, where c is the commission as a decimal:
- Lay stake
free bet × (back − 1) ÷ (lay − c) - Liability
lay stake × (lay − 1) - Guaranteed profit
lay stake × (1 − c) - Conversion
profit ÷ free bet × 100
A free bet is not worth its face value
Because the stake is not returned, a free bet only ever hands back the winnings, so even with a perfect lay you keep roughly 70 to 80% of the face value as cash, never the full amount. The closer the lay odds sit to the back odds, the higher the conversion. This calculator assumes a stake-not-returned bet and an exchange to lay on, only ever lay a bet you can cover the liability for, and always check the bookmaker's own terms before relying on any number.
For information only. 19+ (18+ in AB, MB and QC). Please play responsibly.