Middle calculator

A middle is two bets on opposite sides at different lines, like the underdog +3.5 and the favorite −2.5. If the result lands between the lines, both bets win. Anywhere else one wins and one loses, which usually costs a little vig. On whole-number lines, a result right on the line is a push.

Middle = win on bet A + win on bet B
One side only = win on that bet − stake on the other
EV = middle chance × middle + (1 − middle chance) × the average of the one-side results

Underdog +3.5 and favorite −2.5, both at −110 for $110.

What is middling in sports betting? Betting both sides at different lines so a result between them wins both bets. Lines move during the week, so an early bet at one number and a later bet at another can leave a gap.

How often do middles hit? It depends on the numbers. In the NFL a gap that covers 3 or 7 hits far more often than one that covers 5. Enter your own estimate as the middle chance to see the EV.

What does the EV assume? That when it doesn’t middle, each side is equally likely to win. With equal stakes and similar odds the two one-side results are almost the same, so this barely matters.