Matched Betting Calculator: How to Work Out Your Lay Stake
What a matched betting calculator actually does
A matched betting calculator takes your back bet, the bet placed at a bookmaker, and works out the exact lay stake to place on an exchange like Betfair or Smarkets, so that you profit by roughly the same amount regardless of which outcome happens. Instead of guessing or doing the arithmetic by hand, you enter your back odds, lay odds, and stake, and the calculator returns the lay stake and expected profit or qualifying loss.
Qualifying bet calculator vs free bet calculator
The maths differs slightly depending on whether you're placing a qualifying bet, using your own money and aiming to minimise a small loss, or converting a free bet, aiming to maximise profit since the stake isn't returned if it loses. FavourIQ's Teamer Calculator handles both: switch between qualifying bet mode and free bet mode depending on which stage of an offer you're working through.
Reading the output
The calculator shows your lay stake, how much to place on the exchange, your liability, the maximum you could lose on the exchange side if the bet wins, and your expected outcome across both scenarios. For a qualifying bet, look for the smallest qualifying loss. For a free bet, look for the highest guaranteed profit.
Worked example
Scroll through a month of matched betting and it doesn't look like a highlight reel. It looks like this: back £10 on a draw, lay it off for a guaranteed loss of 96p. Back £5, lay it, -£0.41. Back £20, lay it, -£1.68. Repeated across more than 30 bookmakers, those small guaranteed qualifying losses totalled under £2. The free bets that followed did the real work: a £20 free bet that converted to £61.69, a bet builder free bet worth £85, another worth £77.30, plus dozens of smaller wins adding up bookmaker by bookmaker. Net across the month: £971.43, all worked out the same way each time, back it, lay it, know the number before you place it.
Matched Betting Calculator: How to Work Out Your Lay Stake - FAQ
What's the difference between a qualifying bet calculator and a free bet calculator?
They use the same underlying formula, but a qualifying bet calculator optimises for the smallest loss, since it's your own money at risk, while a free bet calculator optimises for the highest profit, since the stake itself isn't at risk if it loses.
Do I need a separate calculator for accumulators or bet builders?
Multi-leg bets need a different approach since laying every individual leg isn't usually practical or available on exchanges. Most matched bettors either avoid laying multi-leg free bets, accepting the higher variance, or use a specific multi-leg tool rather than the standard calculator.
Why is my lay stake higher than my back stake?
Lay odds are usually slightly higher than back odds due to the bookmaker/exchange price gap and exchange commission, so the lay stake needed to fully cover the potential payout is typically a little more than the original back stake.
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