Enter the back odds at the bookmaker, the lay odds on the exchange, your stake and the commission rate. The calculator returns the lay stake to place, the liability it holds and the qualifying loss you take whichever way the match goes. A £20 qualifying bet at 2.00 back and 2.05 lay costs about £0.69.
The Two Bets in Every Round
Matched betting runs in rounds, and each round has two parts. The qualifying bet is real money placed to satisfy the terms of a bookmaker offer. The free bet is the token that offer releases once the qualifier settles.
You back the qualifier at the bookmaker and lay the same outcome on an exchange. Lay odds usually sit a little above back odds, and the exchange takes commission on winnings, so the two sides do not cancel to zero. The small shortfall left over is the qualifying loss.
Round closes when the token becomes cash. Retention on a stake-not-returned free bet typically runs at 75-80% of face value, so the round nets out at token retention minus qualifying cost.
A Worked Example
A £20 qualifying bet backed at 2.00, laid at 2.05, with 2% exchange commission.
- Lay stake: 2.00 × 20 ÷ (2.05 – 0.02) = £19.70.
- Bookmaker bet wins: -£0.69.
- Exchange lay wins: -£0.69.
- Qualifying loss: roughly £0.69 to unlock the free bet.
Convert the token afterwards and the round comes out well ahead. A £50 free bet converts to around £37.80 at sensible prices, against the 69p it cost to qualify, so the round clears a little over £37 in withdrawable cash. The Free Bet Converter Calculator handles that second step, where a stake-not-returned token gets laid off at longer odds.
How to Read the Results
Lay stake is the only figure you have to act on. Note that the formula divides by lay odds minus commission rather than lay odds alone, which is where hand-calculated lay stakes usually go wrong. Place £19.70 on the exchange and both outcomes settle on the same number.
Matching outcome lines are your check. Back-wins and lay-wins should agree to the penny, and a gap between them means either the lay stake is off or the commission rate does not match your account.
Qualifying loss is the figure to minimise rather than eliminate. Tighter back-to-lay pairs shrink it: 2.00 against 2.05 costs 69p on a £20 stake, and a lay closer to 2.01 would cost less. When an offer pays a £50 token for a £20 qualifier, a pound of qualifying cost either way barely moves the round.
Liability is what the exchange freezes while the market is live, and on short-priced qualifiers it stays close to the back stake. Long-priced qualifiers tie up much more, which is why most matched bettors qualify around even money.
Where Matched Betting Stops Working
Offers are a finite supply. Sign-up offers get used once per bookmaker and never come back. Reload offers are smaller, come with tighter terms, and arrive at the bookmaker’s pace rather than yours.
Accounts get restricted. Bookmakers watch for accounts that only ever bet into promotions, and stake limits or closure arrive without notice. Nothing in the calculator predicts when that happens.
Execution matters more here than in most betting because the margins are so thin. You are working with a 69p cost and a £37 return; one mistyped lay stake, or a lay that never gets matched before kick-off, undoes several rounds of careful work.
Tax treatment of betting winnings varies by country. Check the rules where you live, because nothing on this page is tax advice.
Qualifying bets need no opinion on the match, which is the appeal and also the ceiling. Matched betting extracts money from bookmaker marketing budgets and stops when those budgets do. Pricing markets is the part that keeps running, and Gecko Edge builds a win probability for every market from Poisson goal models with a Dixon-Coles correction, blended with market and league priors, across 130+ leagues. The Back and Lay Calculator and the Arbitrage Calculator cover the other exchange-side arithmetic you will use along the way.
Further Reading
- All betting calculators: the full library of 34 free tools
- Orbit Exchange review: professional exchange betting through a broker
- Glossary: the terms you will see across Gecko Edge
What is a qualifying bet in matched betting?
A qualifying bet is the real-money bet you place to meet the terms of a bookmaker offer and release a free bet. You lay the same outcome on an exchange so the result of the match barely affects you. What remains is a small qualifying loss, roughly £0.69 on a £20 bet backed at 2.00 and laid at 2.05 with 2% commission.
Why does the qualifying bet lose money?
Two reasons, both small. Lay odds sit above back odds, so laying off costs slightly more than the back bet can return, and the exchange takes commission on any winning lay. In the worked example those two effects combine to 69p on a £20 stake. Choosing back and lay prices that sit closer together is the only way to shrink it.
How do I work out the lay stake for a qualifying bet?
Multiply the back odds by your stake, then divide by the lay odds minus your commission rate expressed as a decimal. For £20 at 2.00 back and 2.05 lay with 2% commission: 2.00 × 20 ÷ (2.05 – 0.02) = £19.70. Dividing by the raw lay odds instead leaves you exposed to the result.
Will bookmakers restrict my account for matched betting?
Often, eventually. Bookmakers monitor accounts that bet only into promotions, and they respond with stake limits, withdrawn offers or closure. There is no notice period and no appeal in most cases. Treat the offer supply as finite and plan for accounts to stop producing rather than assuming a permanent income stream.