Exchange betting: back, lay and liability

Two sides of the same market

Backing supports an outcome happening; laying takes the opposite position. On an exchange, matching depends on a counterparty being available at the requested price and amount.

Calculate the liability

For a lay bet at decimal odds of 4.00 with a backer’s stake of €10, liability is 10 × (4 − 1) = €30. The amount at risk is therefore not simply €10. This calculation excludes commission and other applicable conditions.

Liquidity and partial matching

A displayed price may be available only for a limited amount. Part of a request can remain unmatched. Whether the remaining portion can be changed or cancelled depends on the market status and platform rules.

Commission and comparison

Distinguish gross results from results after commission. Do not apply a generic percentage without checking the account and jurisdiction. A comparison with a sportsbook must use the same selection and actual costs.

Not guaranteed income

Taking opposite positions does not automatically remove risk: price changes, liquidity, suspensions and incomplete matching can prevent the expected result. Exchange betting remains gambling and can cause losses.

Links & further reading

Bookmaker links below open information pages on TestedBookies.com, not the operators’ websites. Check current terms on the applicable official edition.

Numerical examples are illustrative calculations. The terms of the individual service take precedence over general descriptions.

Betfair Link

Source review: 6 September 2026. A public webpage does not replace checking account terms or a local licence.