Matched Betting Calculator

Work out the lay stake, liability, and guaranteed profit (or qualifying loss) for a matched bet, using back odds, lay odds, stake, and exchange commission.

Quick Facts

Qualifying bet lay stake
Lay stake = Back stake x Back odds / (Lay odds - Commission)
Commission is entered as a decimal (5% = 0.05) inside the formula.
Free bet lay stake
Lay stake = Free bet x (Back odds - 1) / (Lay odds - Commission)
Only winnings are hedged, since a free bet's stake is not returned if it loses.

Your Results

Calculated
Lay stake
-
Amount to lay at the exchange
Liability
-
Funds needed in exchange account
Guaranteed result
-
Same whether the bet wins or loses
Return on stake
-
Guaranteed result as % of stake

Ready

Enter your bet type, stake, odds, and commission, then press Calculate.

About the Matched Betting Calculator

Matched betting is a technique for extracting value from a bookmaker's free bet or bonus offer (or, for a qualifying bet, for locking in a near-zero-cost outcome) by placing two opposing bets: a back bet at a fixed-odds bookmaker, and a lay bet at a betting exchange that bets against the same outcome. Sized correctly, the two bets cancel out so the result is close to identical whichever way the event goes.

The core formulas

For a qualifying bet (your own money, full stake returned on a back win), the lay stake that hedges a back stake B at back odds Ob, against lay odds Ol with exchange commission c (as a decimal), is:

Lay stake = (B x Ob) / (Ol - c)

For a free bet (stake not returned, "SNR"), only the potential winnings need hedging, not the stake itself, so the formula drops one unit of back odds:

Lay stake = (B x (Ob - 1)) / (Ol - c)

In both cases, the liability — the amount the exchange holds against your lay bet — is Lay stake x (Ol - 1). That is the amount you must have available in your exchange account before placing the lay.

How to get the best results

  • Use decimal (European) odds for both the back and lay legs — fractional odds must be converted first (e.g. 5/2 = 3.50 decimal).
  • Enter the exchange's commission rate as a percentage of net winnings, not of the full payout — most exchanges charge 2-5%.
  • Odds move quickly; place the lay bet as close as possible to the back bet to avoid the hedge drifting out of balance.

Practical context

A qualifying bet typically returns a small guaranteed loss (a few percent of stake) — that loss is the cost of unlocking a bookmaker's free bet offer, not a mistake. A free bet, by contrast, typically returns 70-80% of its face value as guaranteed profit, because only the winnings (not the stake) needed to be matched. Always confirm the exact odds and commission at the time of betting, since the calculator's guarantee only holds for the numbers you enter.

Frequently Asked Questions

What is the matched betting lay stake formula?
For a qualifying (real-money) bet, lay stake = (back stake x back odds) / (lay odds - commission), where commission is the exchange's cut expressed as a decimal (5% = 0.05). For a free bet where the stake is not returned, lay stake = (free bet stake x (back odds - 1)) / (lay odds - commission), since only the winnings need to be hedged, not the stake itself.
How is the liability on the lay bet calculated?
Liability is the amount you must have available in your exchange account to cover the lay bet if it loses. It equals lay stake x (lay odds - 1). This is the money the exchange holds as collateral in case the selection you laid actually wins at the bookmaker.
Why is there a small qualifying loss on a real-money bet?
Matching a real-money qualifying bet almost always costs a small amount because the lay odds at the exchange are slightly higher than the back odds at the bookmaker, and the exchange charges commission on lay winnings. That gap is the qualifying loss, typically a few percent of the stake, and it is the price paid to unlock a bookmaker's free bet offer.
Why does matching a free bet still leave a profit?
With a free bet, the stake itself is not your money, so if the back bet loses you only lose the (already free) stake, while the lay bet at the exchange wins and pays out. Because only the winnings from the back bet need hedging, the lay stake is smaller relative to the free bet value, and the calculator typically returns 70-80% of the free bet's face value as guaranteed profit after commission.

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