Matched Betting Calculator
Work out the guaranteed profit from a bookmaker free bet by calculating the correct lay stake on a betting exchange. Used whenever you receive a free bet offer.
Last updated: September 2026
Formula below · 1 source (Wikipedia) · Updated Sep 2026
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About this calculator
Matched betting extracts risk-free profit from bookmaker free bet promotions by combining a back bet (at the bookmaker) with an opposing lay bet (at an exchange). This calculator handles the usual stake-not-returned free bet, which pays only the winnings if it wins. Lay stake: L = freeBetAmount × (backOdds − 1) / (layOdds − commission/100). If your selection wins, you collect freeBetAmount × (backOdds − 1) from the bookmaker and pay the lay liability L × (layOdds − 1) at the exchange. If it loses, the free bet costs you nothing and the lay wins L, minus commission: L × (1 − commission/100). The lay stake above makes the two outcomes equal, so the locked-in profit is: profit = freeBetAmount × (backOdds − 1) × (1 − commission/100) / (layOdds − commission/100). Higher back odds and lay odds close to them retain more of the free bet; typical retention is 70–80% of its face value.
How to use
You have a $30 free bet (stake not returned). You find back odds of 4.0 at the bookmaker and lay odds of 4.1 at the exchange, which charges 5% commission. Step 1 — back profit if the selection wins: $30 × (4.0 − 1) = $90. Step 2 — lay stake: $90 / (4.1 − 0.05) = $22.22. Step 3 — if the selection wins: $90 − $22.22 × 3.1 liability = $90 − $68.89 = $21.11. Step 4 — if it loses: the lay wins $22.22 minus 5% commission = $21.11. Either way you lock in $21.11, or 70% of the free bet's face value. With the default inputs ($50 free bet) the profit is $35.19.
Frequently asked questions
How do I find matching back and lay odds close enough to maximise profit?
The closer the back and lay odds are to each other, the higher your matched betting profit, because a smaller lay stake is needed to cover the back side. Use odds-matching software or comparison tools to scan multiple bookmakers and exchanges simultaneously for tight spreads. Liquid markets such as top-flight football, horse racing, and major tennis attract the tightest lay prices. Avoid illiquid markets where the spread between back and lay odds is wide, as this erodes your guaranteed profit significantly.
What is the difference between a stake-returned and stake-not-returned free bet?
A stake-returned (SR) free bet credits both winnings and the original stake if it wins, behaving like real money. A stake-not-returned (SNRB or SNR) free bet only pays out the winnings if it wins — the stake itself is not returned, which is why the formula uses freeBetAmount × (backOdds − 1) rather than freeBetAmount × backOdds. Most promotional free bets from bookmakers are stake-not-returned, which yields slightly lower matched-betting profit than a stake-returned equivalent.
Is matched betting legal and can bookmakers close my account for doing it?
Matched betting is legal in jurisdictions where sports betting is permitted, as it exploits promotional terms rather than any loophole in the law. However, bookmakers are private businesses and can restrict or close accounts they identify as bonus hunters. Common signs that trigger account restrictions include consistently betting only when promotions are active, always backing at maximum odds, and rapidly withdrawing funds. To reduce detection risk, experienced matched bettors vary their bet sizes, occasionally place recreational bets without promotions, and prioritise promotions from a wide range of bookmakers.