Matched Betting Calculator
Calculate optimal lay stakes for qualifying bets and free bets. Minimize losses on qualifiers and maximize guaranteed profit from free bet offers, risk-free.
Inputs
Results
Overall Offer Value
Calculate net profit for a complete "Bet X Get X" offer: qualifying loss plus free bet profit.
Qualifying Loss Optimizer
Shows qualifying loss % across back odds at your current lay odds (2.02) and 5% commission. Lower is better.
Compare Offers
Find which free bet gives the highest guaranteed profit at current lay odds.
How Matched Betting Works
Find a Free Bet Offer
Sign up to a bookmaker offering a free bet promotion (e.g., "Bet $50, get a $50 free bet"). These are widely available for new customers.
Place the Qualifying Bet
Place a back bet at the bookmaker on an event with close back/lay odds. Simultaneously, place a lay bet on a betting exchange (like Betfair) on the same outcome.
Accept the Small Loss
The qualifying bet will result in a small loss due to the odds spread and exchange commission. This is the cost of unlocking the free bet. Use this calculator to minimize it.
Place the Free Bet
Once you receive your free bet, place it on a selection with higher odds (4.0+). Lay the same outcome on the exchange. Switch to "Free Bet (SNR)" mode above to calculate.
Collect Your Profit
Regardless of the outcome, you lock in a guaranteed profit from the free bet. Typical retention is 70-80% of the free bet value. Subtract the qualifying loss for your net profit.
Understanding Matched Betting
What is Matched Betting?
How Lay Betting Works
Exchange Commission
Risk-Free Profit Explained
lay_stake = (back_odds × back_stake) / (lay_odds − commission%)lay_stake = ((back_odds − 1) × back_stake) / (lay_odds − commission%)lay_stake = (back_odds × back_stake) / (lay_odds − commission%)liability = lay_stake × (lay_odds − 1)decimal commission, e.g. 0.05 for 5%, denominator = lay_odds − 0.05Active Promos
Select a promo from your sportsbook and auto-fill the calculator fields.
Step-by-Step Workflow
Select a promo
Pick an offer from the Promo Selector above, or enter values manually.
Find qualifying bet
Open the calculator in Qualifying mode. Copy the back odds from your sportsbook.
Get lay odds
Find matching lay odds at Betfair or Smarkets. Enter commission (usually 5%).
Place qualifying bet
Place the back bet at the sportsbook and the lay bet at the exchange simultaneously.
Convert free bet
Switch to Free Bet (SNR) mode. Use your free bet credit on a high back-odds market.
Log your profit
Click "Log Current Calculation" below to track your running P&L.
Profit Tracker
The Complete Guide to Matched Betting
Matched betting is a technique that uses bookmaker free bets and promotional offers to guarantee a profit regardless of the outcome. It is not gambling in the traditional sense. There is no element of chance when executed correctly. By placing opposing bets on both sides of an outcome, you lock in the free bet value as cash. Thousands of people use matched betting as a reliable side income, and this guide explains exactly how it works.
How Matched Betting Works
The core mechanic is simple: you place a "back" bet at a bookmaker (betting on an outcome to happen) and simultaneously place a "lay" bet at a betting exchange (betting against the same outcome). These two bets cancel each other out, meaning you neither win nor lose regardless of the result. The profit comes from the free bet: when you use a free bet on the back side, you keep whatever profit the lay side does not absorb. This is a mathematical lock, not a hunch or a system.
Qualifying Bets: The Cost of Entry
Most bookmaker offers require you to place a "qualifying bet" before receiving the free bet. For example, "Bet $10 and get a $30 free bet." The qualifying bet is placed using your own money, and because the back and lay odds are never perfectly equal, you will typically lose a small amount, usually 1-5% of the stake. This is the "qualifying loss," and it is the cost of unlocking the free bet. The free bet profit will always exceed this qualifying loss by a wide margin.
SNR vs SR Free Bets
The two types of free bets have very different conversion rates. Stake Not Returned (SNR) free bets are the most common: you receive the profit from a winning free bet but not the stake itself. Typical conversion rate: 70-80% of face value. Stake Returned (SR) free bets return both the profit and the stake if the bet wins, yielding close to 100% conversion. Always check the terms to know which type you are dealing with. It dramatically affects your lay stake calculation. Use our free bet converter to get exact numbers.
Step-by-Step: Your First Matched Bet
Step 1: Sign up with a bookmaker offering a welcome bonus (e.g., "Bet $10 Get $30 Free").
Step 2: Find a market with tight odds between the bookmaker and an exchange.
Step 3: Calculate the correct lay stake using the calculator above. This accounts for exchange commission and ensures minimal qualifying loss.
Step 4: Place the qualifying back bet at the bookmaker and the lay bet at the exchange simultaneously.
Step 5: Wait for the qualifying bet to settle. You will have a small loss (typically $0.30-$0.50 on a $10 bet).
Step 6: Use the free bet on a high-odds selection, lay the same outcome at the exchange, and lock in 70-80% of the free bet face value as guaranteed profit.
Free Bet Conversion Rates by Odds Range
Higher odds generally produce higher conversion rates for SNR free bets, because the unreturned stake becomes a smaller proportion of the total payout. Here are typical rates:
| Back Odds | Approx. Lay Odds | SNR Conversion | SR Conversion |
|---|---|---|---|
| 2.0 | 2.02 | ~49% | ~98% |
| 4.0 | 4.1 | ~73% | ~97% |
| 6.0 | 6.2 | ~81% | ~96% |
| 8.0 | 8.4 | ~85% | ~95% |
| 10.0 | 10.5 | ~86% | ~95% |
Common Pitfalls to Avoid
Wrong odds or wrong market: Always triple-check you are backing and laying the exact same outcome. A mismatch means you have two open bets instead of a hedge.
Human error on stake: A mistyped lay stake can turn a risk-free bet into a real gamble. Use the calculator above to eliminate this risk.
Exchange commission: Exchanges charge 2-5% commission on net winnings. This is factored into the calculator but easy to forget when doing manual math.
Gubbing: Bookmakers may restrict accounts that only use promotions. Placing occasional "mug bets" (normal-looking wagers) can delay this, but it happens eventually to most matched bettors.
For more tools to support your matched betting workflow, see the free bet converter for precise stake calculations, the odds converter for switching between formats, and the hedge calculator for more complex multi-leg hedges.
Automate Your Matched Betting
GAMB·8 tracks free bet offers, calculates optimal stakes in real-time, and alerts you to the best opportunities across dozens of bookmakers.