Lay liability: what you need on the exchange
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When you lay a selection on a betting exchange, you take the bookmaker’s side for that outcome. If the selection wins, you pay the backer. The amount you stand to lose is your liability. If you do not have enough available cash to cover it, the exchange will not accept the lay, and your bookmaker back bet is left unprotected.
Work through the figures in the calculator with your own odds before you place a bet. For the wider process, see the beginner guide and the first-offer walkthrough.
What liability is
On a back bet, the most you can lose is the stake. On a lay bet:
Liability = lay stake × (lay odds − 1)
If you lay £10 at odds of 3.00, your liability is £10 × (3.00 − 1) = £20. The exchange holds back that £20 from your balance when it accepts the lay. If the selection wins, you lose the £20. If it loses, you receive the lay stake minus commission.
Open the lay ticket (the exchange’s bet slip) and check the liability it shows before you confirm. It should match the calculator, allowing a penny for rounding.
Liability grows with a larger lay stake and with longer lay odds. That is why a free bet at high odds can need far more exchange cash than its face value, even when the lay stake looks modest. See SNR vs SR for how the type of free bet changes the lay stake.
How to calculate it
You need the lay stake first. Match Sterling uses the same formulas as the site calculator. Commission is a decimal (2% = 0.02). Illustrative examples on this site use 2%. Always use the rate on your account.
Cash qualifying bet or SR free bet
lay stake = back stake × back odds ÷ (lay odds − commission)
SNR free bet (stake not returned)
lay stake = free bet × (back odds − 1) ÷ (lay odds − commission)
Then liability = lay stake × (lay odds − 1). The calculator also shows both outcomes, so you can compare them before you bet.
Worked example (illustrative)
A £10 qualifying back bet at 3.00, laid at 3.10, with 2% commission.
Lay stake = 10 × 3.00 ÷ (3.10 − 0.02) = 30 ÷ 3.08 ≈ £9.74
Liability = 9.74 × (3.10 − 1) ≈ £20.45
| Bookmaker (back) | Exchange (lay) | |
|---|---|---|
| Stake | £10 | about £9.74 |
| Odds | 3.00 | 3.10 |
| Commission | none | 2% |
| Liability | — | about £20.45 |
Outcomes for this step alone are about −£0.45 whichever way the selection goes. That is the qualifying loss at prices this far apart. Closer back and lay odds reduce it.
Cash required on the exchange for this lay: about £20.45. You also need the £10 at the bookmaker for the back stake, so you need money in both places.
Compare a free-bet step at longer odds. A £10 SNR free bet backed at 5.00 and laid at 5.20 (2% commission) needs a lay stake of about £7.72 and a liability of about £32.42. The free bet’s face value is £10, but the exchange needs more than three times that. This catches many beginners out.
How much to keep in the exchange
There is no single correct balance. A practical approach:
- Fund the liability for the bet you are about to place, plus a little extra in case the odds move. If the calculator shows £32.42, do not leave exactly £32.42. A one-tick move against you can raise it.
- Think in offers, not single bets. The free-bet liability is often larger than the qualifying bet’s, so size the exchange balance for that step.
- Fund the bookmaker and the exchange separately. Money in a pending withdrawal does not cover a new lay.
- Withdraw what you do not need once an offer has settled, so large balances are not left scattered longer than necessary.
As a rough guide from this site’s walkthrough figures, a £10 short-odds qualifying bet may need around £10–£15 of liability. A £10 SNR free bet at mid-to-long odds often needs £30–£45 or more. These are illustrations only, so always recalculate.
If you cannot cover the liability, do not place the back bet “and sort the lay later”. A back bet with no matched lay is an ordinary gamble.
Common mistakes
- Confusing lay stake with liability. At odds above 2.00, liability is larger than the lay stake.
- Using the SNR lay stake for a cash bet (or the reverse). The wrong lay stake means the wrong liability. Pick the matching bet type on the calculator.
- Forgetting commission. Leaving commission at 0% gives the wrong lay stake and wrong figures for both outcomes.
- Odds moving after you back. If the lay price lengthens before anything has matched, recalculate the whole lay before you confirm. If part of the lay has already matched, do not treat that new whole-bet stake as an extra lay.
- Part-matched lays. If only some of your lay matches, you are only partly covered. Cancelling the unmatched remainder does not cancel the stake already matched. The calculator has no matched-stake or old-price input, so its full-bet lay is not an extra stake to place on top. Account for the matched exposure with a partial-match method that uses that stake and price, or accept the exposure. See part-matched.
- Draining the exchange between the qualifying bet and the free bet. You may not be able to lay the free bet when it arrives.
- Ignoring void and settlement differences. If one side is voided and the other is not, the matched-bet maths no longer works cleanly.
Risks that remain
Having enough to cover the liability is necessary, but it is not enough on its own. Odds can move, lays can fail to match, wrong selections cost money and bookmakers can restrict accounts (gubbing). Calculations do not mean a bet will be accepted, or that both operators will settle it the same way. If you are unsure, pause and recheck the terms and numbers.
Next steps
Practise in the calculator, follow the first-offer walkthrough, check the free-bet type on SNR vs SR and use the glossary for unfamiliar words.
An each-way bet has a win lay and a place lay. The each-way calculator shows both. The term is in the glossary.
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