On an exchange, a back bet and lay bet must be matched with opposing customer offers. Betfair's exchange introduction shows the separate available-to-back and available-to-lay prices; this spread and the available stake matter to the calculation.
How Matched Betting Works
The process involves two key steps: a qualifying bet and a free bet extraction.
Step 1: The Qualifying Bet
If an offer requires a qualifying cash bet, its terms define the minimum odds, eligible markets, timing, and settlement conditions. The calculation must include the qualifying result rather than treating the later token as costless.
One possible hedge is to back an outcome with the bookmaker and lay exactly the same settlement outcome on the exchange. Different rules for extra time, non-runners, abandoned events, or voids can leave the bets unmatched in substance even when the labels look alike.
Step 2: Extracting the Free Bet
Once the free bet is credited, you repeat the process. Back an outcome at the bookmaker using the free bet, and lay the same outcome on the exchange. Because the free bet is stake-not-returned, the maths works differently.
If an SNR token back bet wins, it pays the odds-derived winnings but does not return the token amount; the lay position loses. If the back selection does not win, the token pays nothing and the lay position wins, less applicable commission. Betfair's commission documentation confirms that its standard exchange commission is calculated on net market winnings, with the actual rate depending on the customer and market.
Worked Example
This is a fully illustrative calculation using a 5% exchange commission assumption. It is not a live offer or price quote.
Qualifying bet:
| Action | Details |
|---|---|
| Back bet | Selection A at 2.50, 10 pound cash stake |
| Lay bet | Selection A at 2.52, 10.12 pound lay stake |
| Lay liability | (2.52 - 1) x 10.12 = 15.38 pounds |
| Net result | About -0.38 pounds in either outcome after 5% commission |
The equalising lay stake is (back odds x back stake) / (lay odds - commission rate): (2.50 x 10) / (2.52 - 0.05) = 10.12. If Selection A wins, the net is 15 - 15.38 = -0.38. If it does not win, the net is -10 + (10.12 x 0.95) = -0.38, allowing for rounding.
Free bet extraction (first 10 free bet):
| Action | Details |
|---|---|
| Back bet | Selection B at 4.00, 10 pound SNR token |
| Lay bet | Selection B at 4.10, 7.41 pound lay stake |
| Lay liability | (4.10 - 1) x 7.41 = 22.97 pounds |
| Net result | About 7.03 pounds in either outcome after 5% commission |
For an SNR token, the equalising lay stake is (token amount x (back odds - 1)) / (lay odds - commission rate): (10 x 3) / (4.10 - 0.05) = 7.41. If Selection B wins, the net is 30 - 22.97 = 7.03. If it does not, the net is 7.41 x 0.95 = 7.04, allowing for rounding. Subtracting the illustrative 0.38 pound qualifying loss leaves about 6.65 pounds for the complete sequence.
Why It Works Mathematically
The calculation chooses a lay stake that makes the two projected net results similar. It does not eliminate operational risk, and it works only for the prices, commission, and settlement assumptions entered. Rounding the lay stake can also leave a small difference between outcomes.
Verification Checklist
- Confirm both bets describe the same outcome and settlement period.
- Enter the accepted back odds, available lay odds, token type, and your actual commission rate.
- Check lay liability against the exchange balance before submitting.
- Confirm the lay bet is fully matched; an unmatched request is not a hedge.
- Save both receipts and recheck stakes, prices, teams, event, and market.
- Include the qualifying result, fees, voids, and expired tokens in the final record.
Limitations and Risks
Matched betting is not without challenges:
- Execution error. A wrong event, market, selection, stake, price, or token type can create open exposure.
- Price movement. The available lay price can change before the second bet is matched.
- Liquidity. Only the stake shown at a price is immediately available; the remainder may stay unmatched.
- Commission and rounding. The applicable rate and allowed stake increments change the equalising stake.
- Rule mismatch. Extra time, abandonment, void, and settlement-source differences can make nominally opposing bets settle differently.
- Offer conditions. Minimum odds, excluded markets, cash-out restrictions, expiry, and qualifying requirements can invalidate the planned sequence.
Important Considerations
Matched betting is an execution and pricing calculation, not a prediction that a team will win. Read the current terms for both products, including the exchange rules in this worked example, and do not describe a projected return as guaranteed.
Past performance does not guarantee future results.
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Related resources
Continue with Lay Bet: What It Means in Betting for the next part of this topic, or return to Betting Glossary: Every Betting Term Explained in Plain English to compare the other guides in this collection.
Continue learning
- Next guide: Odds-On
- Related guide: Over/Under Goals
- Go deeper: Value Betting vs Matched Betting
Assumptions and limitations
The worked SNR example assumes both prices remain available, the back token and lay stake are accepted, the selection and settlement rules match, and commission applies only as stated. Rounding and partial matching can leave unequal outcomes. Betfair's exchange guide and rules illustrate one platform; promotion terms and legality vary.
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