Matched Betting Calculator — Lay Stake & Free Bet Profit

The matched betting calculator handles two distinct scenarios: placing a qualifying bet to unlock a free bet offer, and converting a free bet (SNR) into guaranteed cash. Select the bet type using the toggle, then fill in four fields:

1. Back Stake / Free 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).
2. Back Odds (Decimal) — the decimal odds available at the bookmaker for the selection you want to back.
3. Lay Odds (Decimal) — the decimal 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.
4. 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.

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.

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 75–80%. 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

1. Sign up at a bookmaker offering a welcome bonus (e.g. "Bet $10, Get $10 Free Bet").
2. Place a qualifying bet — back a selection at the bookie and lay it at the exchange. Accept the small qualifying loss.
3. Receive your free bet — the bookmaker credits the bonus after your qualifying bet settles.
4. 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.
5. Repeat — move on to reload offers, acca insurance, and price boosts at the same bookmaker and work through every available sign-up offer.