Middle Calculator
You bet a spread or total at one line, the line moved, and now you can grab the opposite side at a different number. If the result lands between the two — both bets cash.
The middle, in plain math
A middle is two bets on opposite sides of the same market at different lines. Bet -7.5 and +8.5: if the favorite wins by exactly 8, both bets cash. That gap (here, 1 point — the 8) is the middle window.
Most middles lose one side and win the other — the cost is one bet's vig. The big payday only happens when the result lands inside the window. Whether that's a good bet depends on how often the window hits historically (key football numbers like 3, 7, 10 hit far more than 1 or 2-point windows).
only_A = profit_A − stake_B
only_B = profit_B − stake_A
Where middles come from: line moves, key-number arbitrage between books, and bought lines. They're cheaper to chase than arbs because both legs share the same game and you can usually get them with a single account on each book.