Find profitable middle opportunities where two spread or total lines create a window where both bets can win. Enter both sides and the calculator shows probability of the middle hitting and your profit/loss scenarios.
Side A (lower number)
Bookmaker
Line number
American odds
Decimal odds
Side B (higher number / other side)
Bookmaker
Line number
American odds
Decimal odds
Enter both sides to calculate the middle opportunity
Middle window
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Gap between lines
Middle probability
—
Est. chance both win
EV of middle
—
Expected value
How middles work
The middle window
When you bet Side A at -1.5 and Side B at +2.5, any result of exactly 2 makes both bets win. The gap between the two lines is your middle window.
Middle probability
Estimated using a normal distribution around the line. Wider windows and closer-to-even lines have higher middle probability. This is an estimate, not a guarantee.
No middle hits
If the middle doesn't hit, one bet wins and one loses. If both lines are at -110, you lose the vig. The key question: does the middle probability justify the vig cost?
When to chase
Middle opportunities with windows of 2+ points and near-even odds are generally worth taking. Our EV calculation shows whether the opportunity has positive expected value.