This lay bet calculator works out what a lay risks and what it wins. Type the lay odds and either the lay stake or the liability you can carry, plus your own commission rate: laying $35 at $3.80 risks $98 to win $32.20 at an illustrative 8% rate.
The stake box on an exchange slip is not the amount at risk: the price minus 1 multiplies it into the liability. To size a lay against a back bet you already hold, use the back lay calculator.
How to use the lay bet calculator
- Amount entered as: Lay stake, the backer's stake you accept, or Target liability, the most you will lose, in dollars.
- Lay odds, the decimal price in the lay column.
- Commission rate (%): your own account's rate, because rates differ by account and market. The box opens at the worked example's illustrative 8%, so type your own over it, or 0 if none applies.
Liability is what you pay if the selection wins, Lay stake is the backer's stake, and each answers the other. Keep if it loses is that stake less commission, and Effective lay price is the commission-free equivalent explained below.
Money shows to the cent and prices to two places, and a trailing dot counts, so 4. reads as $4.00 while you type. Nothing shows, and a line says why, for an empty or unreadable box, an amount outside $0.01 to $1,000,000, a price outside $1.01 to $10,001, or a rate outside 0% to 50%. The same goes for a target liability needing over $1,000,000 of lay stake.
Lay bet formulas: liability, stake and commission
In dollars and decimal odds, with the rate as a fraction (8% is 0.08):
- liability = lay stake x (lay odds - 1)
- lay stake = liability / (lay odds - 1)
- keep if the selection loses = lay stake x (1 - commission rate), when it is your only bet in that market
- effective lay price = 1 + (lay odds - 1) / (1 - commission rate)
A lay worked at $3.80
Example: illustrative prices and an illustrative 8% rate, not a real market. You lay a runner for $35 at $3.80.
| Result | What happens | Working | Profit |
|---|---|---|---|
| The selection loses | You collect the $35 stake, less commission | 35 x (1 - 0.08) | +$32.20 |
| The selection wins | You pay the backer's profit | 35 x (3.80 - 1) | -$98.00 |
The lay wins $32.20 and loses $98, so it breaks even when the selection wins 32.20 / (32.20 + 98) = 24.7% of the time. The $3.80 price implies 1 / 3.80 = 26.3%, and at that chance the lay averages (1 - 1 / 3.80) x 32.20 - (1 / 3.80) x 98 = -$2.06.
Working back from a liability you can carry
A $100 limit at an illustrative $4.33 allows 100 / (4.33 - 1) = $30.03 of lay stake, and at an illustrative 6% rate the win on it is 30.03 x 0.94 = $28.23.
That direction is the one a Betfair Starting Price (BSP) lay needs. Its price is not known until the jump, so where your exchange offers one the bet is entered as a liability limit and the stake follows the price. With illustrative prices and the same $100 limit at the illustrative 6%:
| BSP | Lay stake the $100 allows | Keep if it loses |
|---|---|---|
| $2.20 | $83.33 | $78.33 |
| $4.33 | $30.03 | $28.23 |
| $7.50 | $15.38 | $14.46 |
A liability limit fixes the loss and lets the win float, so check your exchange's terms. How to lay a bet covers the slip, and liability the number at its centre.
What commission does to the price you lay at
Commission takes a share of the win and none of the loss, so it is a worse price, not a flat fee. On a $3.80 lay, with illustrative rates:
| Rate | Effective lay price | Working |
|---|---|---|
| 0% | $3.80 | 1 + 2.80 / 1.00 |
| 2% | $3.86 | 1 + 2.80 / 0.98 |
| 5% | $3.95 | 1 + 2.80 / 0.95 |
| 8% | $4.04 | 1 + 2.80 / 0.92 |
At 8% the $3.80 in the lay column is really a $4.04 lay (1 + 2.80 / 0.92 = $4.0435), which implies 24.7%, the break-even chance above. Exchange commission explained covers how a rate is charged across a market.
Risk: Betting involves risk. The effective price is arithmetic on the rate you typed, and a lay priced well can still cost you the liability. See responsible gambling for limits and support.
Partial matches, rounding and prices under $2.00
Every price and rate below is illustrative.
A lay is a bet only for the part a backer takes, so type the matched amount in. Ask to lay $75 at $3.20, have $48 matched, and the bet you hold is $48: the liability is 48 x 2.20 = $105.60 and the win at 5% is $45.60.
The other $27 is only an offer, but it can still be matched before the jump, adding 27 x 2.20 = $59.40 of liability, so cancel it or type the new amount (see unmatched bets).
Rounding bites in Target liability mode: a slip takes a stake to the cent, so a $100 limit at $3.70 wants 100 / 2.7 = $37.037. The $37.04 you can type carries 37.04 x 2.70 = $100.01, or round down to $37.03 for $99.98.
At $2.00 the liability equals the stake, and below it the liability is smaller: $120 at $1.75 risks 120 x 0.75 = $90 to win $114. The win only beats the loss below 2 minus the rate, $1.95 at 5%, and at $1.75 the price implies you pay out 1 / 1.75 = 57.1% of the time.
Three lay mistakes and what each one costs
With illustrative prices and rates:
| Mistake | What it costs | The fix |
|---|---|---|
| Reading the stake box as the amount at risk | Typing $98 as the lay stake at $3.80 makes the liability 98 x 2.80 = $274.40 | Switch to Target liability and type $98, for a $35 lay stake |
| Keeping the example's 8%, or a 0, when your account's rate differs | An $80 win is $76 at 5% but $73.60 at 8%, so the wrong rate is out by $2.40 | Read the rate off your own account and type it |
| Typing 0.05 for 5% | The box reads a percentage, so 0.05 means 0.05% and an $80 win shows $79.96 | Type 5 or 5% |
The lay betting hub covers where laying fits beside backing.
Finding the lay price to type in
The Terminal shows Betfair's back and lay columns beside prices from 40+ bookmakers across racing and sports, read on a repeating cycle, so confirm it on the exchange first. B337 does not place exchange bets, so the lay goes on by your own hand. Bookmaker names are trade marks of their owners. B337 is not affiliated with them.
Risk: Betting involves risk. A lay matched in pieces can leave you with a bigger or smaller bet than you sized, an exchange can reprice a matched bet under its own scratching rule, and there is no guarantee of profit. See responsible gambling for limits and support.