Matched Betting Calculator — Lay Stake & Free Bet Profit
Calculate matched betting stakes for qualifying bets and free bets. Find the optimal lay stake to minimize qualifying loss and maximize free bet value.
Odds format
Saved for all betting calculators
Amount to bet at the bookmaker
Odds at the bookmaker
Lay odds on Betfair / Smarkets / etc.
Betfair standard = 5%; Smarkets = 2%
Qualifying Loss:
−$0.50
Qualifying Bet — Minimize Your Loss
Lay Stake (Exchange)
$10.00
Lay Liability
$11.50
Profit if Back Wins
−$0.50
Profit if Back Loses
−$0.50
Qualifying Loss (approx.)
−$0.50
Last reviewed · How we check our calculators
How to Use the Matched Betting Calculator
The matched betting calculator handles three bet types: a Qualifying Bet to unlock a free bet offer, a Free Bet (UK SNR) to convert into guaranteed cash, and a Bonus Bet (US) paid in site credit. Select the bet type using the toggle, then fill in four fields:
- Back Stake / Free Bet Amount / Bonus Bet Amount — the amount you are staking at the bookmaker. For a qualifying bet this is real money; for a free bet this is the value of the bonus (which is not returned if you win — hence Stake Not Returned, SNR). A bonus bet returns its stake with the winnings, so the two outcomes differ: the result shows both — what you end on if the back bet wins and if it loses.
- Back Odds at Bookie — the odds available at the bookmaker for the selection you want to back, in the odds format you picked.
- Lay Odds at Exchange — the odds available to lay the same selection on a betting exchange (Betfair, Smarkets, Matchbook). These should be as close to the back odds as possible to minimize the qualifying loss.
- Exchange Commission (%) — the commission your exchange charges on winning lays. Betfair standard is 5%; Smarkets charges 2%; Matchbook can be as low as 1%. Enter the correct rate for your exchange.
The calculator outputs the exact lay stake to place at the exchange, the lay liability (funds you must have in your exchange account), and the profit or loss in each outcome. For qualifying bets, this reveals the small loss you accept to unlock the free bet. For free bets, it shows how much cash you will retain.
The Formula
Matched betting uses algebra to find a lay stake that produces equal results in both outcomes. Here is the full derivation for each scenario.
Qualifying Bet
Let S = back stake, B = back odds, L = lay odds, c = commission as a decimal (e.g. 0.05 for 5%), and X = lay stake.
- Profit if back wins = S(B − 1) − X(L − 1)
- Profit if back loses = X(1 − c) − S
Setting these equal and solving for X:
S × B = X × (L − c)
X = S × B / (L − c)
Free Bet SNR (Stake Not Returned)
The back stake is a free bet — it is not returned with the winnings if the back selection wins, and it is not lost if the back selection loses (the bookmaker absorbs it).
- Profit if back wins = S(B − 1) − X(L − 1) (win minus lay liability)
- Profit if back loses = X(1 − c) (no stake lost since it was a free bet)
Setting equal and solving:
S(B − 1) = X(L − c)
X = S × (B − 1) / (L − c)
Because the free bet stake is not at risk, both profits are positive, and the average retained value is typically 70–90% of the free bet amount at tight odds.
Practical Examples
Example 1 — Qualifying Bet ($10, odds 2.0 / 2.1, 5% commission)
A bookmaker requires a $10 qualifying bet to unlock a $10 free bet. The best available back odds are 2.00; the exchange lay odds are 2.10 at 5% commission.
- Lay stake = $10 × 2.00 / (2.10 − 0.05) = $20 / 2.05 ≈ $9.76
- Lay liability = $9.76 × (2.10 − 1) ≈ $10.73 (funds locked in exchange account)
- Profit if back wins = $10 × 1.00 − $10.73 ≈ −$0.73
- Profit if back loses = $9.76 × 0.95 − $10 ≈ −$0.73
- Qualifying loss ≈ −$0.73 — a small, predictable cost to unlock the free bet.
Example 2 — Free Bet SNR ($10 free bet, 2.0 / 2.1, 5% commission)
You have received the $10 free bet. The same market is still available: back at 2.00, lay at 2.10.
- Lay stake = $10 × (2.00 − 1) / (2.10 − 0.05) = $10 / 2.05 ≈ $4.88
- Lay liability ≈ $4.88 × 1.10 ≈ $5.37
- Profit if back wins = $10 × 1.00 − $5.37 ≈ +$4.63
- Profit if back loses = $4.88 × 0.95 ≈ +$4.63
- Free bet value retained ≈ $4.63 (46.3%)
In total (qualifying loss + free bet value): −$0.73 + $4.63 = +$3.90 profit from a $10 sign-up offer. Across dozens of bookmakers, matched bettors routinely extract hundreds of dollars per month from welcome bonuses alone.
Improving Free Bet Returns
The key to maximising free bet returns is choosing selections with high back odds and low lay odds spread. At odds of 4.0 / 4.1, the free bet SNR return rises to approximately 70.4%. Dedicated matched bettors use odds-matching software to find the closest back/lay pairs across all available markets before placing.
The Full Matched Betting Cycle
- Sign up at a bookmaker offering a welcome bonus (e.g. "Bet $10, Get $10 Free Bet").
- Place a qualifying bet — back a selection at the bookie and lay it at the exchange. Accept the small qualifying loss.
- Receive your free bet — the bookmaker credits the bonus after your qualifying bet settles.
- Place your free bet (SNR) — back a selection at the bookie with the free bet token and lay it at the exchange. Retain 70–90% as cash profit.
- Repeat — move on to reload offers, acca insurance, and price boosts at the same bookmaker and work through every available sign-up offer.
Frequently Asked Questions
Yes, matched betting is entirely legal. You are simply using publicly available betting offers and placing bets on a licensed exchange. It is not gambling in the traditional sense because the mathematical lay stake eliminates directional risk. However, bookmakers reserve the right to limit or close accounts they identify as matched bettors, so longevity of access to bookmaker accounts is a practical concern.
A qualifying bet is a real-money bet you place to unlock a free bet offer. You accept a small loss (typically 1–5% of the stake) to trigger the bonus. A free bet (SNR — Stake Not Returned) is the bonus token itself. When you win using a free bet, you receive only the winnings and not the stake back; when you lose, you lose nothing from your own pocket. The matched betting calculator handles both scenarios with different lay stake formulas.
SNR stands for Stake Not Returned. It describes the most common type of bookmaker free bet: if your selection wins, the bookmaker pays out the winnings only and keeps the free bet token amount. For example, a $10 SNR free bet on a 2.00 selection returns $10 in winnings, not $20. This is the standard behaviour and is factored into the free bet lay stake formula.
Enter the commission rate charged by your exchange on winning lay bets. Betfair's standard rate is 5%, though it varies by market and can be lower for high-volume customers. Smarkets charges 2% by default. Matchbook and other exchanges can be as low as 1–2%. Using an accurate commission rate is important because even small differences affect the optimal lay stake and your retained free bet value.
New matched bettors can typically extract $500–$1,500 from sign-up offers alone within the first few weeks, depending on which country they are in and how many bookmakers are available to them. Ongoing profits from reload offers, loyalty promotions, and enhanced odds vary but experienced UK-based matched bettors often report $300–$800 per month. Returns decrease over time as bookmaker accounts get restricted, so diversification across many books is key.
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