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Matched betting calculator

The lay stake that levels a back bet, your liability, and the result either way.

The bookmaker bet is
%
Lay stake9.74
If the bookmaker bet wins−0.45
If the exchange lay wins−0.45
Liability20.45
Know which side is the good one

Matched betting levels the bet. If you would rather back the side the price has wrong, a BAI8 assessment gives you the real chance of each outcome.

Free plan: 5 assessments a month, no card needed.

Assess a match free

How it works

Matched betting backs an outcome at a bookmaker and lays the same outcome at a betting exchange, with a lay stake that makes the result the same whichever way the event goes. For a qualifying bet, the lay stake is the back stake times the back odds, divided by the lay odds less the exchange’s commission.

A free bet whose stake is not returned is laid on its winnings only. That is why its lay stake is smaller, and why a free bet keeps most of its value when the back and lay odds are close.

The formula

  • Qualifying bet: lay stake = back stake × back odds ÷ (lay odds − commission)
  • Free bet, stake not returned: lay stake = free bet × (back odds − 1) ÷ (lay odds − commission)
  • Free bet, stake returned: lay stake = free bet × back odds ÷ (lay odds − commission)
  • Liability = lay stake × (lay odds − 1)

A worked football example

Back a home win with 10.00 at 3.00 and lay it at 3.10 on an exchange charging 2% commission. Lay 9.74, with a liability of 20.45, and you finish on −0.45 whichever way the match goes. A free bet of 10.00 (stake not returned) at 5.00, laid at 5.20, levels at +7.57: it keeps 75.7% of its value.

What it does not tell you

The calculator assumes both bets stand and the exchange matches your lay at that price. It cannot see your bookmaker’s terms for the free bet or the commission you actually pay, and it says nothing about which side of the match is the better bet.

Common questions

How do I calculate a lay stake?

For a normal bet, multiply the back stake by the back odds and divide by the lay odds minus the commission. Backing 10 at 3.00 and laying at 3.10 with 2% commission: 30 ÷ 3.08 = 9.74.

What is liability on a lay bet?

What you pay out if the outcome you laid wins: the lay stake times the lay odds minus 1. Laying 9.74 at 3.10 carries a liability of 20.45, which the exchange holds while the bet is open.

What is the difference between SNR and SR free bets?

An SNR free bet (stake not returned) pays only the winnings. An SR free bet (stake returned) also gives back the free bet’s stake. SNR is laid on its winnings alone, so its lay stake is smaller.

How much of a free bet can I keep?

It depends on the odds and the gap between back and lay. A free bet of 10 at 5.00, laid at 5.20 with 2% commission, keeps 7.57. Longer odds keep more, as long as the back and lay prices stay close.

Why does commission matter?

The exchange takes its commission from what a winning lay collects, so the lay stake is divided by the lay odds minus the commission. The higher the commission, the more a qualifying bet costs.

Read more

Lay betting explainedBlogBetting exchange odds explainedBlogPrice boosts explained: what an enhanced price is worthBlogLay betGlossaryBetting exchangeGlossaryHedgingGlossary

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