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  1. Home
  2. Gambling Tools

Back/Lay Calculator

Calculate optimal lay stakes for matched betting and trading

Formula:Lay Stake = (Back Odds × Stake) / (Lay Odds - Commission)

Bet Type

Lock in equal profit regardless of outcome

Back Bet (Bookmaker)

Your qualifying/cash bet

$

Lay Bet (Exchange)

Exchange odds and commission

%

Matched Bet Results

Qualifying loss calculated

Recommended Lay Stake
$98
Liability: $207
If Back Bet WINS
-$7

Win back bet, pay lay liability

If Back Bet LOSES
-$7

Lose back stake, win lay profit

Calculation Breakdown

Back Bet
$100 @ 3
Lay Bet
$98 @ 3.1
Lay Liability
$207
Commission
$5

Lay Stake

$98

Liability

$207

Avg Profit

-$7

Retention

46.7%

Qualifying Loss: This bet will result in a small loss of approximately $7 to unlock your free bet bonus. This is normal for qualifying bets.

Try These Examples

Common back/lay scenarios

Matched Bet Tracker

0 / 100 entries

Bet History

0 entries

No bets recorded yet.

Add your first bet to start tracking.

How Back/Lay Matching Works

Understanding matched betting

Example: $100 Qualifying Bet

  • 1. Back: $100 @ 3.00 with bookmaker
  • 2. Lay: $98.36 @ 3.10 on exchange (5% comm)
  • 3. If selection wins: +$200 back win, -$196.72 lay liability = +$3.28
  • 4. If selection loses: -$100 back loss, +$93.44 lay win = -$6.56
  • 5. Worst case: Small qualifying loss to unlock free bet
Normal Mode

For qualifying bets using real money. Small loss expected.

SNR Free Bet Mode

Stake Not Returned. Different formula for optimal lay stake.

Quick Answer

TL;DR summary

The Back/Lay calculator finds the optimal lay stake to match a back bet. For a $100 back bet at 3.00 odds, laying at 3.10 with 5% commission: Lay Stake = (3.00 × $100) / (3.10 - 0.05) = $98.36. This locks in ~$3.19 profit regardless of outcome. Essential for matched betting and trading positions.

Key Facts About Back/Lay Matching

Important things to know

  • Back/lay matching locks in profit regardless of outcome
  • Normal mode: Lay Stake = (Back Odds × Stake) / (Lay Odds - Commission)
  • SNR Free Bet: Lay Stake = ((Back Odds - 1) × Stake) / (Lay Odds - Commission)
  • SR Free Bet: Lay Stake = (Back Odds × Stake) / (Lay Odds - Commission) - same as normal
  • Closer back and lay odds = higher profit retention
  • Underlay: Accept more profit if back wins, loss if back loses
  • Overlay: Accept more profit if back loses, loss if back wins
  • Aim for lay odds within 0.1-0.2 of back odds for best results

Frequently Asked Questions

Common questions about back/lay matching

What is back/lay matching?

Back/lay matching involves placing a back bet with a bookmaker and a lay bet on an exchange on the same outcome. By calculating the correct lay stake, you can guarantee the same profit (or loss) regardless of whether the selection wins or loses. This is the foundation of matched betting.

What is a qualifying bet?

A qualifying bet is a bet placed to unlock a free bet bonus. The goal is to minimize losses while meeting the bookmaker's requirements. By back/lay matching a qualifying bet, you typically lose 1-3% of the stake due to odds differences and commission, but gain access to a valuable free bet.

What's the difference between SNR and SR free bets?

SNR (Stake Not Returned) free bets only return winnings, not the stake. SR (Stake Returned) free bets return both winnings and stake. SNR free bets require a different lay stake calculation since you won't get the stake back if you win. SNR is more common.

What is underlay and overlay?

Underlay means betting less on the lay side than optimal, accepting more profit if the back wins but a loss if it loses. Overlay means betting more on the lay, accepting more profit if the back loses but a loss if it wins. Both are used for strategic reasons or when exact matching isn't possible.

Why might back and lay odds be different?

Exchange odds (lay) may differ from bookmaker odds (back) because: exchanges charge commission, markets have spreads between back and lay prices, bookmakers may have better odds on promotions, and market efficiency varies between platforms.

How much profit can I expect from matched betting?

From qualifying bets: expect 0-5% loss. From free bets: expect 70-95% profit of the free bet value depending on odds. A $50 free bet typically returns $35-47 profit. Higher back odds and closer lay odds increase returns.