How it works
Every price says the same thing three ways: what a winning bet pays. American odds, the US standard, are built around $100. A plus price is the profit on a $100 bet, and a minus price is the stake that wins $100. Decimal odds are the total return on each $1, the stake included. Fractional odds are the profit over the stake.
The converter reads the field you type in as a decimal price, then writes that price out in the other formats. The implied chance is 1 ÷ the decimal price: how often a bet at that price has to win to break even.
The formula
Plus price: decimal = 1 + American ÷ 100+130 → 1 + 1.30 = 2.30
Minus price: decimal = 1 + 100 ÷ |American|−150 → 1 + 100 ÷ 150 = 1.667
Fractional a/b: decimal = 1 + a ÷ b13/10 → 1 + 1.30 = 2.30
Implied chance = 1 ÷ decimal1 ÷ 2.30 = 43.48%
American = (decimal − 1) × 100 from 2.00 up, or −100 ÷ (decimal − 1) below 2.00
A worked NFL example
An NFL moneyline has the favorite at −150 and the underdog at +130.
- Favorite in decimal: 1 + 100 ÷ 150
- 1.667
- Favorite in fractional: the profit over the stake
- 2/3
- Favorite's implied chance: 1 ÷ 1.667
- 60.00%
- Underdog in decimal: 1 + 130 ÷ 100
- 2.30
- Underdog in fractional
- 13/10
- Underdog's implied chance: 1 ÷ 2.30
- 43.48%
A $100 bet on the favorite returns $166.67 if it wins: the $100 back, plus $66.67 profit. The same bet on the underdog returns $230. The two implied chances add up to 103.48%, not 100%. The extra is the sportsbook’s margin, which the no-vig calculator takes out.
Common mistakes
- Reading a minus price as a loss. −150 doesn’t mean losing $150. It is the stake that wins $100, and a losing bet loses only what was staked.
- Forgetting the stake in decimal odds. 2.30 returns $2.30 for each $1, so the profit is $1.30. Fractional odds, 13/10, are the profit alone.
- Trusting a rounded decimal. −110 is 1.9091 in decimal, usually shown as 1.91. But 1.91 is exactly −109.89, and 1.90 is −111.11. Type the price the way the book shows it.
- Taking the implied chance as a forecast. It is the break-even rate at that price, with the book’s margin in it, not the chance the book gives the team.
In Unitley
Unitley’s slate shows each NFL game’s moneyline, spread and total with the chance each price implies, so there is nothing to convert. See what the slate shows.