Matched Betting Calculator

Matched betting turns bookmaker free bets and promotions into guaranteed profit — but only if your lay stake is exactly right. Get it wrong and you lose on one side or the other. Our free matched betting calculator works out the precise lay stake for qualifying bets and both types of free bet (SNR and SR), with exchange commission already factored in. No spreadsheets, no guesswork.

Back Stake (£)

Back Odds

Lay Odds

Lay Commission (%)

Back Commission (%)

Part Lays

Part Lays Already in Place

Lay: £ @ odds:

Under Lay

Standard Match

Over Lay

Custom Match

Drag slider left and right to alter your custom lay

18+ Only. Gambling should be fun. Never bet money you cannot afford to lose.

What Is Matched Betting?

Matched betting is a technique that uses the free bets and sign-up offers that bookmakers hand out to new and existing customers. By placing a back bet at the bookmaker and a corresponding lay bet at a betting exchange such as Betfair or Betdaq, you cover all possible outcomes of an event. The bookmaker’s free bet money then produces a profit regardless of what happens on the pitch or track.

The mathematics only works when your lay stake is calculated precisely. A few pence out on a standard qualifying bet becomes several pounds out on a £50 free bet. That is why a dedicated matched betting calculator is essential not a rough estimate, not a rule of thumb.

Why Punters Lose Money on Matched Betting

Matched betting is essentially risk-free when done correctly. These are the five most common mistakes that turn a guaranteed profit into an avoidable loss:

Confusing SNR and SR free bets. A Stake Not Returned (SNR) free bet is worth less than a Stake Returned (SR) free bet of the same face value, because with SNR you do not get the stake back if the bet wins. Using the wrong formula wipes out a significant chunk of the expected profit.
Forgetting exchange commission. Betfair charges 2–5% on winning lay bets. Ignoring it means your “matched” position is not actually matched you will lose a small amount every single time the back bet wins, across every offer you ever work.
Choosing the wrong lay option. Under Lay, Standard Match, and Over Lay produce very different outcomes. Most beginners default to Standard Match without realising that Under Lay or Over Lay can be better depending on the odds gap between the back and the lay market.
Not accounting for part lays. If you already hold a partial lay position on a selection, laying the full calculated amount again will leave you over-exposed. The Advanced mode in this calculator handles part lays correctly.
Back and lay odds diverging between calculation and placement. Odds move. If you calculate your lay stake at 3.20 and the market moves to 3.40 before you get matched, your positions are no longer balanced. Always recalculate before confirming.

The 3 Bet Types in the Calculator, Qualifying, SNR, and SR Explained

Qualifying Bet

The majority of bookmaker free bets are Stake Not Returned. This means that if your free bet wins, you only receive the profit not the stake amount back on top. A £20 SNR free bet at odds of 3.00 returns £40 in profit, not £60 total. The formula to extract value from an SNR free bet is different from a qualifying bet, and the calculator handles this automatically when you select the SNR tab.

As a rough guide, a well-matched SNR free bet typically extracts 70–80% of its face value as guaranteed profit. A £20 SNR free bet should therefore produce around £14–£16 after commission. Higher odds generally improve SNR extraction because the free bet stake represents a smaller proportion of the potential return.

Free Bet SR (Stake Returned)

A Stake Returned free bet pays out the full amount including the original stake if it wins. This makes it more valuable than an SNR free bet of the same face value, and it also changes the optimal lay strategy. SR free bets behave more like real-money bets in terms of the maths. Select the SR tab in the calculator and it will give you the correct figures do not use the SNR formula on an SR offer or you will under-extract by a meaningful margin.

Under Lay, Standard Match, and Over Lay — Which Should You Choose?

The calculator produces three different lay stake options and the results look very different from each other:

Under Lay — you lay less than the standard matched amount. On SNR and SR free bets, if the back bet wins, you return exactly your original back stake. This is the preferable option when the lay odds are noticeably higher than the back odds, as it reduces your exchange liability while still producing a profit on the lay side.
Standard Match — you lay the exact amount that produces an equal outcome whether the back or lay side wins. Both outcomes give you the same profit or loss figure. This is the textbook matched betting position.
Over Lay — you lay more than the standard matched amount. On SNR and SR free bets, if the lay bet wins (the selection loses), you return your original back stake. This works better when the back odds are higher than the lay odds, as over-laying reduces the gap between the two outcomes.

The calculator shows the exact lay stake, liability, and both outcome positions for all three options side by side. Use the copy icon next to each lay stake to paste it directly into your exchange without retyping eliminating the risk of a costly typo.

How to Use the Matched Betting Calculator

Choose your bet type. Click Qualifying Bet, Free Bet (SNR), or Free Bet (SR) depending on the offer you are working on.
Enter the back stake. For a qualifying bet this is the cash you are placing. For free bets, this is the face value of the free bet token.
Enter the back odds. Use the exact decimal odds shown at the bookmaker at the moment you intend to place the bet.
Enter the lay odds. Use the best available lay price on the exchange for the same selection. Decimal odds only convert fractional or American odds first if needed.
Enter the lay commission. The default is 3%, which suits most standard Betfair accounts. Check your current rate in your exchange dashboard and update it accordingly.
Read the three result panels. Each panel shows your lay stake, your exchange liability, the outcome if the back bet wins, and the outcome if the lay bet wins. Pick the option you prefer, then click the copy icon to grab the stake.
Switch to Advanced mode for back commission or part lays. Advanced mode adds a back commission field (for bookmakers that charge on winnings) and a Part Lays section if you already hold a partial position on the exchange.

Simple Mode vs Advanced Mode

Simple mode covers everything needed for the vast majority of everyday matched betting: back stake, back odds, lay odds, and exchange commission. It outputs the lay stake and both outcome positions in under a second.

Advanced mode adds two additional inputs:

Back commission – some bookmakers, particularly those operating on a betting exchange model, charge a percentage on winning back bets. If yours does, enter the percentage here and the calculator adjusts the “Bookies Back wins” figure accordingly.
Part Lays Already in Place – if you have already placed part of your lay (for example, because you caught the market early at a better price), tick the Part Lays checkbox and enter your partial lay details. The calculator tells you exactly how much of the remaining lay you still need to get matched.

5 Tips to Get More From Every Matched Betting Offer

Always match on a liquid market. Horse racing and top-flight football both have tight spreads between back and lay odds. Obscure leagues and niche sports have wide spreads that inflate your qualifying loss.
Target odds of 3.0–5.0 for SNR free bets. This bracket typically gives the best balance between extraction percentage and manageable exchange liability. Very short prices give poor extraction; very long prices make it hard to get matched quickly.
Recalculate if odds move before you are fully matched. Even a 0.1 movement in lay odds changes your liability and your outcome positions noticeably. Refresh the calculator with the new odds before confirming at the exchange.
Keep your exchange account funded with a buffer. Being unable to place a lay because your exchange balance is slightly short at the precise moment you need it is one of the most avoidable matched betting problems. Keep at least 20–30% more than your largest expected liability available.
Log every offer in a spreadsheet. Track qualifying loss, free bet extracted, and net profit for each promotion. Over time the pattern becomes clear and you can prioritise the bookmakers whose reload offers deliver the best returns.

More Free Betting Calculators

Use our full suite of free tools alongside the matched betting calculator:

Staking Plan Calculator -Work out how much to stake per bet using Percentage Staking, Fixed Staking, or the Kelly Criterion. Essential for managing your betting bank.
UK Bet Calculator – All Bet Types Returns for every UK bet type: Singles, Doubles, Patents, Yankees, Lucky 15s, Heinz, Goliath and more, with full each-way support.
Each-Way Bet Calculator – See exactly how much you win on the win part versus the place part across different fractions and number of places.
Lay Bet Calculator – Calculate your liability and effective back odds for any lay position on Betfair or Betdaq.

Matched Betting Calculator, Frequently Asked Questions

Is matched betting actually risk-free?

When you use a matched betting calculator correctly and place your bets at the calculated stakes, your outcomes are fixed and you make a profit regardless of the result. The risk comes from human error placing the wrong lay stake, using the wrong odds, or ignoring commission. The calculator eliminates the arithmetic risk; the execution is down to you.

What is the difference between a qualifying bet and a free bet?

A qualifying bet uses your own real money to unlock a promotional offer — the goal is to minimise the qualifying loss. A free bet uses the bookmaker’s token money, so it has no cost to you regardless of the outcome. Because the free bet stake itself is costless, the maths changes significantly and the calculator uses different formulas for each type.

What does SNR mean in matched betting?

SNR stands for Stake Not Returned. If your free bet wins, you receive the profit only the stake is not paid back to you on top. The vast majority of UK bookmaker free bets are SNR. The alternative, SR (Stake Returned), pays out profit plus the original stake and is worth more for the same face value. Always confirm which type you have before calculating your lay stake.

What exchange commission rate should I enter?

Betfair’s standard rate is 5%, but most active accounts sit at 2–4% through their discount structure. Betdaq charges 2% and Smarkets charges 2%. Log into your exchange and check your actual rate in account settings even a 1% error compounds across dozens of bets and erodes your overall profit. Enter your exact rate in the Lay Commission field.

How much profit can you make from matched betting?

New customer sign-up offers across major UK bookmakers typically yield £500–£1,500 combined when worked systematically and calculated correctly. Ongoing reload offers, enhanced odds, and money-back specials that existing customers receive add further earning potential. The amount depends on how many bookmaker accounts you open, how quickly odds move before you get matched, and how well you manage your exchange funds.

Does this calculator work for Betfair, Betdaq, and Smarkets?

Yes. Enter the lay odds and your specific commission rate for whichever exchange you are using. Betfair charges 3–5% depending on your account, Betdaq charges 2%, and Smarkets charges 2%. The lay stake, liability, and outcome figures will then be accurate for that platform.

Contents hide

1 Part Lays Already in Place

6 What Is Matched Betting?

7 Why Punters Lose Money on Matched Betting

8 The 3 Bet Types in the Calculator, Qualifying, SNR, and SR Explained

8.1 Qualifying Bet

8.2 Free Bet SR (Stake Returned)

9 Under Lay, Standard Match, and Over Lay — Which Should You Choose?