A double lay means laying the same selection twice, at two moments or at two prices, around an offer whose payout is decided partway through the event. The usual case is an early payout, where the bookmaker settles a head to head bet as a winner the moment your team reaches the lead its terms name. That turns an unknown bookmaker payout into a known one while your exchange lay is still running, and a position that was balanced an hour ago is suddenly a bet on the result.
This page works one position all the way through with illustrative prices: $100 at $2.50 with the bookmaker, laid at $2.55 on an illustrative 5% commission rate, and an early payout of $250 that lands during the game. It shows what the second stake has to be, which direction it has to go in, and what it costs when it is not matched. This is an advanced technique with more ways to go wrong than a single hedge.
What a double lay is
Laying is betting that a selection will not win, as lay betting sets out in full. A matched position is one back bet with the bookmaker and one lay at an exchange, sized so the two cancel whichever way the event goes.
A double lay is that position with a second lay added on the same selection. Two situations produce one:
- The first lay was only part matched at the price you wanted, so the rest goes on later at whatever is available. Same selection, two prices, one intended position.
- An offer's condition is settled during the event, so the exchange leg is adjusted once the bookmaker payout is known rather than guessed at.
The second situation is where the name is used most and where it goes wrong most, because once a bookmaker has settled a bet early, a second lay makes the exposure bigger rather than smaller. The arithmetic below shows exactly that.
Why one lay leaves you exposed when a payout can fire early
A normal matched position has two outcomes and two legs, and the legs cancel. An early payout splits one of those outcomes in two: the team reaches the lead, the bookmaker pays, and the team then fails to win anyway. Early payout promotions puts a value on that branch; this page is about the leg that closes it.
The problem is what happens to the lay. Your bookmaker bet has been settled and paid, and nothing in the rest of the game changes it. Your exchange lay is still live and still settles on the real result. One leg has stopped moving and the other has not, which is the definition of an open position.
Note: Australian bookmakers close online betting on a match once it has started, so the bookmaker side of the position cannot be adjusted mid-game. An exchange keeps trading, so every correction after the first whistle happens there.
The sequence, in order
Four steps, and the third is the one that needs someone watching.
- Place the back bet with the bookmaker before the event, inside whatever maximum stake the offer's terms set.
- Lay the same selection at an exchange before the event, sized so the position costs the same whichever way the game goes.
- Watch for the trigger. If the bookmaker settles the bet early, work out the second stake against the payout that has now been made.
- Place the second leg at the exchange and check it is matched. If it is not matched, the position is still open.
Step 3 is not a sum you can set up in advance, because the price you will get at step 4 is whatever the market is trading at after the trigger, and that depends on how the game is going.
Worked example: $100 at $2.50 with an early payout
Example: Illustrative prices, an illustrative 5% commission rate, and not a current offer or a real game. You back Team A for $100 at $2.50 with the bookmaker, on an account that already holds an early payout, and lay Team A at an exchange at $2.55.
The pre-event lay stake uses the standard rule:
lay stake = back stake x back odds / (lay odds - commission rate) = 100 x 2.50 / (2.55 - 0.05) = 250 / 2.50 = $100.00
Liability is 100 x (2.55 - 1) = $155.00, and a winning lay pays 100 x (1 - 0.05) = $95.00 after commission. The back lay calculator runs the same sums at your own prices.
| Outcome, no trigger | Back bet | Lay bet | Net |
|---|---|---|---|
| Team A wins | +$150.00 | -$155.00 | -$5.00 |
| Team A does not win | -$100.00 | +$95.00 | -$5.00 |
Now the trigger fires. The bookmaker settles the bet as a winner and pays $250: the $100 stake back plus $150 profit. That $150 is banked and cannot change. The lay is untouched.
| Outcome, after the early payout | Bookmaker, settled | Lay bet | Net |
|---|---|---|---|
| Team A wins | +$150.00 | -$155.00 | -$5.00 |
| Team A does not win | +$150.00 | +$95.00 | +$245.00 |
That is a $250 swing riding on the rest of the game, and removing it is the whole point of a second leg.
What a second lay actually does here
Say Team A is two goals up and trading at an illustrative $1.30, and you lay another $50 there. Liability is 50 x (1.30 - 1) = $15.00, and both lays winning pays (100 + 50) x 0.95 = $142.50.
- Team A wins: 150 - 155 - 15 = -$20.00
- Team A does not win: 150 + 142.50 = +$292.50
The swing has gone from $250 to $312.50. Laying again on a bet the bookmaker has already paid out adds to the side of the market you are already on, so it cannot close anything.
The leg that does close it
The closing leg is a back bet at the exchange, at the price trading after the trigger. Its stake is the exchange swing divided by that price:
back stake = lay stake x lay price / new price = 100 x 2.55 / 1.30 = 255 / 1.30 = $196.15
- Team A wins: 150 - 155 + 196.15 x (1.30 - 1) = 150 - 155 + 58.85 = +$53.85
- Team A does not win: 150 + 100 - 196.15 = +$53.85
The exchange market loses $96.15 either way, so no commission is charged in either branch: an exchange takes commission from net winnings in a market, and this market finishes behind. The $53.85 is the bookmaker's banked $150 less that $96.15.
Risk: Betting involves risk. Bookmakers can restrict or close accounts and void bets, prices move, and a positive expected value bet can still lose. There is no guarantee of profit. See responsible gambling for limits and support. The $53.85 above assumes both exchange legs are matched in full at the prices shown, and the trigger fires in only some games.
Sizing the second leg against a known payout
The arithmetic changes because the two stakes answer different questions.
| Question | First leg | Second leg |
|---|---|---|
| What it covers | A payout that may or may not happen | A payout that has already been made |
| Inputs | Back stake, back odds, lay price, commission | Current lay stake, its price, the new price |
| Stake | back stake x back odds / (lay price - commission) | lay stake x lay price / new price |
| Direction | Lay | Back, once the bookmaker has settled early |
Both come from the same idea: make the two branches equal. The commission rate sits in the first divisor because a winning lay is paid net of commission, so a $100 lay at a 5% rate brings in $95 rather than $100. It drops out of the second because, once the closing back bet is on, the exchange market finishes behind in both branches, and a market that finishes behind is charged no commission at all. By then the bookmaker side is the same fixed number in both branches, so it cancels out of the equation entirely.
When the second bet really is a lay
There is one case where the second leg genuinely is a lay on the same selection: the first lay was never matched in full. Prices move and the money at your price runs out, so $60 of an intended $100 goes on at $2.55 and the market drifts to $2.65 before the rest can be placed.
With two lay prices, the rule to balance on is:
back stake x back odds = lay 1 x (price 1 - commission) + lay 2 x (price 2 - commission)
Example: Illustrative prices again. $100 at $2.50 needs 100 x 2.50 = 250. The first lay of $60 at $2.55 supplies 60 x (2.55 - 0.05) = 150, so the second lay has to supply 100. At $2.65 that is 100 / (2.65 - 0.05) = 100 / 2.60 = $38.46.
Total liability is 60 x 1.55 + 38.46 x 1.65 = 93.00 + 63.46 = $156.46, and both lays winning pays (60 + 38.46) x 0.95 = $93.54.
- Team A wins: 150 - 156.46 = -$6.46
- Team A does not win: -100 + 93.54 = -$6.46
Balanced again, but at $6.46 rather than the $5.00 the position would have cost had the whole $100 matched at $2.55. The drift on the unmatched part cost $1.46, and nothing recovers that.
Risk: Betting involves risk. Splitting a lay across two prices balances the position at a worse number, not a better one, and a lay you cannot place at all leaves the back bet uncovered. There is no guarantee of profit. See responsible gambling for limits and support.
Liquidity, timing and the leg that never matches
Everything above assumes the market will take the bet. Four practical constraints decide whether it does.
Liquidity at two moments, not one. A pre-event exchange market can be deep and the same market thin an hour later, or the other way around. You need enough money on the other side at both moments, and the second one arrives without warning.
Someone has to be watching. The trigger fires during play. A position left alone until the final whistle keeps whichever branch the game delivered, which on the worked numbers is minus $5 or plus $245.
An unmatched leg is a real exposure. A back of $196.15 that sits unmatched is not a smaller hedge, it is no hedge: the $155 liability is still at risk and the swing is still $250. Unmatched bets covers what happens to one at the off.
Stakes and terms are the bookmaker's call. Offer terms set the eligible markets, the maximum stake and the margin that triggers the payout, and the bookmaker decides whether a bet qualifies. Many bookmakers' terms also restrict automated betting, third-party tools and bets of this shape, and they can limit stakes, void bets or close an account. No software prevents an account being restricted.
Where B337 fits
B337 is odds comparison and betting automation software, not a bookmaker, and it never holds your money: stakes and returns stay in your own accounts. The Terminal lines up racing and sports prices from 40+ bookmakers side by side with Betfair back and lay beside them, plus price history, closing lines and EV overlays, which is what you read off when you check whether a lay price is worth taking. Prices are read on a repeating cycle rather than tick by tick, so a price on screen can trail the bookmaker's own: confirm it in your account before betting.
What it does not do matters more on this page. B337 places no exchange bet on a sports position of this kind, and there is no exchange trading or green-up in the software, so both legs of a double lay are yours to place in your own exchange account. Bookmaker names are trade marks of their owners. B337 is not affiliated with them. A free account opens a limited view of the Terminal with live odds, and plans and prices lists the rest. Bets placed through B337 also use credits, a per-bet usage charge.
For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au.
Risk: Betting involves risk. Comparing prices does not make a position safe: both exchange legs still have to be matched, the trigger may never fire, and the bookmaker's terms govern every bet. There is no guarantee of profit. See responsible gambling for limits and support.