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Matched Betting Calculator

Exact lay stake for qualifying bets, SNR/SR free bets and money-back offers. Risk-free, guaranteed profit.

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The matched betting calculator tells you the exact lay stake needed to neutralise a back bet at a bookmaker, so the result of a free bet, qualifying bet or money-back promotion is the same regardless of which side wins. It is built for matched bettors and value bettors working welcome offers, reloads and price boosts. Use it before placing every bet that has an exchange leg, especially when commission rates differ between exchanges or the offer is an SNR free bet rather than a stake-returned bet. Pair it with the best matched betting tool review to pick a workflow that fits your stake size and frequency.

Worked Examples

Three illustrative scenarios across the most common matched betting situations. Numbers are hypothetical; treat them as templates, not predictions. All three assume BFB247's 2.5% commission; on SharkBetX at 2%, the same bets need slightly smaller lay stakes and produce slightly better results.

Example 1: Qualifying bet to unlock a free bet

Setup: Consider a hypothetical bettor placing a €20 qualifying bet to unlock a €20 SNR free bet.

Inputs: back_stake = €20, back_odds = 3.50, lay_odds = 3.60, commission = 2.5% (BFB247)

Output: Lay stake = €19.58. Liability = €50.91. Qualifying loss ≈ €0.49.

Interpretation: A sub-€1 qualifying loss is healthy. The free bet that follows converts to roughly €16, so the net effect of the offer is around +€15.50.

Example 2: SNR free bet conversion

Setup: Consider a hypothetical bettor converting a €25 SNR free bet on tennis.

Inputs: free_bet = €25, back_odds = 5.00, lay_odds = 5.20, commission = 2.5% (BFB247)

Output: Lay stake = €19.32. Liability = €81.14. Profit either way ≈ €19.32 (77.3% retention on the free bet face value).

Interpretation: Higher back odds extract more value from SNR free bets, but liability scales fast. Always confirm the exchange has enough liquidity at the lay price before placing the back bet.

Example 3: Money-back-if-loses promotion

Setup: Consider a hypothetical bettor on a "stake €50, get €25 cash back if it loses" offer.

Inputs: back_stake = €50, back_odds = 2.20, lay_odds = 2.26, commission = 2.5% (BFB247), cashback = €25

Output: Lay stake = €37.92. Liability = €47.78. Locked profit ≈ €11.55 either outcome.

Interpretation: Money-back offers behave like partial free bets. The calculator handles the cashback math automatically; manual approximation usually leaves money on the table.

How It Works

Qualifying Bet

Used to unlock a bookmaker bonus or free bet. The goal is to minimize your loss while meeting wagering requirements.

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

SNR Free Bet (Stake Not Returned)

Your stake is NOT returned if you win. This is the most common type of free bet.

Formula: Lay Stake = (Back Odds − 1) / (Lay Odds − Commission) × Free Bet Value

SR Free Bet (Stake Returned)

Your stake IS returned if you win. Same as a normal bet, making it more valuable.

Formula: Lay Stake = (Back Odds × Free Bet Value) / (Lay Odds − Commission)

Money Back if Bet Loses

Some promotions refund part of your stake if the bet loses (e.g., "Bet $10, get $5 back if you lose"). The cashback reduces the effective qualifying loss.

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

Underlay & Overlay

Use the advanced slider to shift profit between the two outcomes. Useful for rollover requirements or when you want more profit on a specific side.

  • •Underlay: Lay less than standard; more profit if back wins, less if lay wins
  • •Overlay: Lay more than standard; more profit if lay wins, less if back wins

Where to Go Next

Tools, comparisons and methodology reading that fit the matched betting workflow.

Best matched betting tools

Side-by-side review of oddsmatchers, calculators and exchange integrations.

OddsMonkey alternative

Why bettors switch from OddsMonkey to Sharkbetting for lower commission and faster matching.

Methodology

How Sharkbetting calculates lay stakes, ratings and qualifying loss across exchanges.

Sharkbetting vs OddsMonkey

Feature-by-feature comparison for matched bettors weighing the two platforms.

Related calculators

Free tools to size lay stakes, sequence offers and check commission once your qualifying bet is placed.

Lay to Back Calculator

Convert an exchange lay bet into its equivalent back stake and liability.

Sequential Lay Calculator

Chain multiple lay bets across a multi-leg free bet offer.

Exchange Commission Calculator

Factor in commission for your exchange lay profits before you place a bet.

Surebet Calculator

Lock in guaranteed profit across bookmakers and exchanges.

Want to Find Matched Betting Opportunities Automatically?

Our Oddsmatcher scans 20+ bookmakers in real-time and finds the best qualifying bets and free bet opportunities for you.

A matched betting calculator, also called a back and lay calculator, tells you exactly how much to lay at a betting exchange to cover a back bet at a bookmaker, so your profit is the same regardless of the outcome. Enter your back stake, back odds, lay odds and commission rate, and it returns the precise lay stake, liability and profit on each side.

The calculator handles four bet types: qualifying bets, SNR free bets (stake not returned), SR free bets (stake returned), and money back offers. Each type uses a different formula, which is why getting this right manually is error-prone.

How to Calculate Your Lay Stake

  1. 1
    Select bet type, Qualifying Bet, Free Bet SNR, Free Bet SR, or Money Back. Each type changes the formula.
  2. 2
    Enter back stake and back odds, the amount and odds at the bookmaker. Example: €20 at 3.50.
  3. 3
    Enter lay odds and commission, the exchange lay price and your commission rate. SharkBetX charges 2%, BFB247 charges 2.5%, Betfair charges 5%.
  4. 4
    Read the results, the calculator shows your lay stake, liability, and profit or qualifying loss across all outcomes.

The Lay Stake Formulas Explained

Each bet type uses a different formula. Here is the maths behind what the calculator computes:

Qualifying bet

Lay stake = (Back odds × Back stake) ÷ (Lay odds − Commission)

Example: Back €20 at 3.50, lay at 3.60 with 2% commission (SharkBetX) → Lay = (3.50 × 20) ÷ (3.60 − 0.02) = €19.55

SNR free bet (stake not returned)

Lay stake = ((Back odds − 1) × Free bet) ÷ (Lay odds − Commission)

A €20 SNR free bet at 3.50 back, 3.60 lay, 2% commission (SharkBetX) → €13.97 lay stake, ~€13.69 profit

SR free bet (stake returned)

Lay stake = (Back odds × Free bet) ÷ (Lay odds − Commission)

Money back offer

Lay stake = (Back odds × Stake − Cashback) ÷ (Lay odds − Commission)

Qualifying Loss vs Free Bet Profit: What the Numbers Mean

A qualifying bet will almost always show a small negative result, typically 2–4% of your stake. That is expected and intentional. You accept a small qualifying loss to unlock a free bet worth far more.

A €20 qualifying bet at odds of 3.50 with a 3.55 lay and 5% commission produces a qualifying loss of roughly €0.80. The €20 SNR free bet that follows converts to around €16 in cash. Net result: approximately €15.20 guaranteed profit from one offer.

Lower commission directly reduces qualifying loss on every bet. This is why SharkBetX at 2% and BFB247 at 2.5% save meaningfully over Betfair at 5% for high-volume matched bettors.

Common Mistakes When Using a Matched Betting Calculator

  • ✕
    Using the wrong bet type. Selecting "qualifying bet" when you have an SNR free bet will give you a completely wrong lay stake. Always confirm which type the promotion is before entering values.
  • ✕
    Ignoring commission. Entering 0% commission when your exchange charges 5% means the lay stake is too low and one outcome loses money. Always enter your actual rate.
  • ✕
    Using back odds instead of lay odds from the exchange. The back price and lay price on an exchange are different. The lay price is always higher than the back price for the same selection.
  • ✕
    Not checking exchange liquidity. If the exchange does not have enough money available to match your full lay stake at those odds, you cannot complete the trade at the calculated price.

Frequently Asked Questions

What is a matched betting calculator used for?

It calculates the exact lay stake needed to cover a back bet, so the profit from a bookmaker free bet or promotion is guaranteed regardless of which outcome wins or loses. Without it, you are guessing, and guessing costs money.

What is a qualifying loss and how do I minimise it?

A qualifying loss is the small deficit from the qualifying bet placed to unlock a free bet. Typically 2–5% of the back stake. Minimise it by finding back and lay odds as close together as possible, and by using a lower commission exchange like SharkBetX at 2% or BFB247 at 2.5% instead of Betfair's 5%.

What is the difference between SNR and SR free bets?

SNR (Stake Not Returned) means only the winnings are paid, not the original stake. SR (Stake Returned) means you get the stake back as well. An SNR free bet is worth roughly 75–85% of face value when converted to cash; an SR bet is worth around 95%. The calculator handles both formulas automatically.

Can I use this calculator for any bookmaker?

Yes. The calculator works for any bookmaker and any exchange. Simply enter the odds and commission rate that apply to your specific accounts. For finding the best available lay odds across exchanges, use the Oddsmatcher.

What does underlay and overlay mean?

Underlay means laying less than the calculated optimal stake, so you profit more if the back bet wins but less if it loses. Overlay is the opposite. Both shift profit between outcomes. For most matched betting scenarios, the balanced calculation is correct.

Is this a lay bet (back and lay) calculator?

Yes, the terms describe the same tool. A back bet is placed at the bookmaker and a lay bet is placed against that selection on a betting exchange. This calculator works out the exact lay stake so the back and lay bets cancel into a guaranteed result. Always enter the lay odds and commission from your exchange, not the back price.

How much can you make with matched betting?

It depends on the offers available, your bankroll and the time you put in. The maths itself is fixed: a typical SNR sign-up free bet converts to roughly 75–85% of its face value as locked profit, and an SR free bet to around 95%. Beyond welcome offers, ongoing returns come from reloads, price boosts and refer-a-friend deals, which vary by bookmaker and season. There is no guaranteed monthly figure, so treat any site that promises one with caution.

Can I use this for each-way matched betting?

Each-way bets split your stake across a win part and a place part, and each part needs its own lay. For those, use the dedicated each-way calculator, which handles the place terms and both lay legs together. This calculator covers single-outcome back and lay bets.

Ready to put these calculations into practice? The matched betting guide walks through the full process from sign-up offer to ongoing profits, and the Oddsmatcher finds the best lay odds automatically. For other guaranteed-profit strategies, see the surebet calculator and the dutching calculator.

Formula and worked examples reviewed by Erik Andersson. How we calculate.