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AiOddsLab

Bet Calculator

Free bet calculator. Enter American odds and your stake — get the payout, profit, decimal odds, and the implied win probability the line assumes.

Payout
$62.50
Profit
$37.50
Decimal odds
2.500
Implied probability
40.00%

Want to know if this bet is actually +EV? Run it through the Slip Analyzer or the EV calculator.

The math behind a bet calculator

Convert American odds to decimal: for positive odds, decimal = (odds / 100) + 1; for negative, decimal = (100 / |odds|) + 1. Payout is just stake × decimal. Implied probability is the inverse — what win rate the price would need to break even before vig.

Worked example — $25 on the Lakers +180

  1. 1
    American odds: +180
  2. 2
    Decimal odds: (180 / 100) + 1 = 2.80
  3. 3
    Payout: $25 × 2.80 = $70.00
  4. 4
    Profit: $70.00 − $25.00 = $45.00
  5. 5
    Implied probability: 100 / (180 + 100) = 35.71%
The book is pricing the Lakers at roughly a 36% chance. If you think their true win probability is higher, the bet is +EV. Compare implied probabilities across lines to spot where the market disagrees.

Frequently asked questions

What does a bet calculator do?+

A bet calculator takes your stake and the sportsbook's odds and tells you the payout (stake + profit), profit alone, and the implied win probability the price assumes. It's the math behind 'what do I win if this hits?'

How is bet payout calculated?+

Convert American odds to decimal. Payout = stake × decimal odds. Profit = payout − stake. Example: $25 at +180 → decimal 2.80 → payout $70, profit $45.

What's the formula for implied probability?+

For negative American odds: |odds| / (|odds| + 100). For positive: 100 / (odds + 100). A −150 line implies 60% win probability; +150 implies 40%.

Does this account for sportsbook vig?+

No — the implied probability includes the book's margin. To find the true fair probability, use the fair odds calculator or devig calculator, which strips the vig from a two-way market.

How is this different from a parlay calculator?+

This calculator handles a single bet. For multi-leg tickets, use the parlay calculator — it multiplies decimal odds across legs to find the combined price, win probability, and payout.