How to use the middle calculator
- Enter the odds and stake of bet A, in any format.
- Enter the odds and stake of bet B.
The calculator shows:
- your profit or loss if only A wins,
- your profit or loss if only B wins,
- your profit if both win (the middle),
- the break-even middle chance: how often the result must land in the gap for the plan to pay off over time.
If the first two results are both positive, you have an arbitrage and the middle is a bonus.
The maths
- Only A wins: stake A × (odds A − 1) − stake B.
- Only B wins: stake B × (odds B − 1) − stake A.
- Both win: stake A × (odds A − 1) + stake B × (odds B − 1).
To make the two single-side results equal, set stake B = stake A × odds A ÷ odds B. The break-even chance is the worst single-side loss divided by the total swing between the middle and that loss.
Example
You bet Over 45.5 at −110 early in the week, and the line moves to 47.5. You bet Under 47.5 at −110 with the same $100.
| Final total | Result | Profit |
|---|---|---|
| 45 or less | Only the Under wins | −$9.09 |
| 46 or 47 | Both win (the middle) | +$181.82 |
| 48 or more | Only the Over wins | −$9.09 |
The middle needs to land 4.8% of the time to break even. In some sports, a gap of two points covers numbers that come up more often than that. That is why bettors look for middles on key numbers, such as 3 and 7 in American football.
Scalping
Scalping is the same idea over time: you bet one side, wait for the odds to move, then bet the other side to lock in a profit. Enter both bets to see the result of each outcome, and use stake B = stake A × odds A ÷ odds B for an equal result.
Tips
- The gap is the edge. A bigger gap between numbers means a higher chance of a middle.
- Mind the margin. A fully balanced middle costs the overround of the two prices.
- Check limits. Some sportsbooks limit or restrict bettors who middle often.
Compare with the arbitrage calculator and the hedge calculator, and read moneyline, spread and totals for how the lines work.
