Lay betting explained: how laying works on exchanges

Lay betting is the reverse of a traditional bet: instead of backing a selection to win, you bet that it will not win. Lay betting only exists on betting exchanges (Betfair, Smarkets, Matchbook) because the platform matches your lay against another punter's back bet at an agreed price.

How a lay bet works

Two terms to know before you place one:

• Lay stake — the amount you stand to win if the selection loses. This is the "stake" in the conventional sense, but it's actually what the backer is risking on you.
• Liability — what you stand to lose if the selection wins. Liability depends on the lay price: liability = lay stake × (price − 1).

Example: you lay Liverpool to win at 3.00 for a £10 lay stake.

• If Liverpool lose or draw, you win £10 (minus exchange commission, typically 2-5%).
• If Liverpool win, you pay £20 to the backer. Liability = £10 × (3.00 − 1) = £20.

When laying is useful

Three common use cases for UK punters:

Matched betting

The most common reason hobbyist punters open exchange accounts. You back a selection with a bookmaker's free-bet stake, then lay the same selection at the exchange to cover yourself. Most outcomes lock in a guaranteed profit regardless of result. The free bet calculator (Free Bet tab on the main calculator) works out the exact lay stake to hit your target return.

Trading and pre-match positions

Pre-event trading involves backing a selection at a longer price, then laying at a shorter one (or vice versa) before the event starts, to lock in a profit on the price movement. This is closer to spread betting than fixed-odds — outcomes move on news, team announcements, and inflows.

Hedging an existing bet

If you backed a 10-fold acca and the first nine legs landed, you might lay the tenth at the exchange to lock in some of the profit instead of risking it all on the final leg. The amount you lay is calculated to give you the same payout whether the leg wins or loses.

Worked example

You're hedging a single bookmaker bet:

• Original bet: £20 on Federer at 3.50 (potential return £70)
• You want to guarantee profit regardless of outcome
• Lay Federer at the exchange at 3.20 (slightly shorter, in your favour)
• Lay stake to hedge: £20 × 3.50 / 3.20 = £21.88
• Liability: £21.88 × (3.20 − 1) = £48.13

Outcomes:

• Federer wins: bookmaker pays £70, you owe exchange £48.13. Net profit £21.87 (less commission).
• Federer loses: bookmaker bet loses £20, exchange pays £21.88. Net profit £1.88 (less commission).

Both outcomes profitable. This is the locked-in trading position laying enables.

Lay-side risks

Three things that catch new layers out:

• Liability scales with price. Laying a long shot at 10.00 for a £10 stake creates £90 of liability. Your account needs to cover the worst case before the bet matches.
• Matched ≠ priced. Posting a lay at 3.20 only fills if a backer wants 3.20. If the market moves and you're left unmatched, you're unhedged.
• Commission compounds. Frequent traders can see 5% commission take a meaningful slice of edge over time. Higher-volume punters often migrate to lower-commission exchanges.

For the deeper picture on why bookmakers and exchanges price the way they do — and why exchange liquidity often beats bookmaker prices on liquid markets — see the cornerstone guide on bookmaker margin and overround. The maths of margin applies equally to exchanges; it's just expressed differently (commission instead of overround).