Quantitative Betting Calculator
Odds Converter
An odds converter translates between American (+150 / −110), decimal (2.50), and fractional (3/2) formats and shows the implied win probability for any price. Enter odds in any format and instantly see the equivalents plus the break-even percentage the price represents.
How the odds converter works
Enter odds in any format
Type an American, decimal, or fractional price and the converter fills in the others. Every format describes the same payout - just written differently for different markets.
See the implied probability
It also shows the implied win probability, which is the break-even rate you'd need to profit at that price. This is the number that actually matters for finding value.
Compare across books and markets
Converting to a single format makes it easy to compare a US book quoting American odds against an exchange quoting decimal - and to spot the better number.
Conversion basics
Decimal = 1 + (American ÷ 100) for plus odds, or 1 + (100 ÷ |American|) for minus odds. Implied probability = 1 ÷ decimal odds.
Example — +150 equals decimal 2.50, fractional 3/2, and an implied probability of 40%. −110 equals decimal 1.909 and an implied probability of about 52.4%.
Frequently Asked Questions
How do you convert American odds to decimal?
For positive American odds, decimal = 1 + (odds ÷ 100). For negative odds, decimal = 1 + (100 ÷ absolute value). So +150 is 2.50 and −200 is 1.50.
What does +150 mean in betting?
+150 means a $100 winning bet returns $150 profit (plus your stake back). It equals decimal 2.50 and an implied win probability of 40%.
What is implied probability?
Implied probability is the win rate an odds price is built around - the break-even percentage you'd need to profit at that price. It equals 1 divided by the decimal odds.
Which odds format is best?
They're interchangeable - decimal is easiest for calculating payouts, American is standard at US books, and fractional is common in the UK. The odds converter lets you work in whichever you prefer.
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Apply This Math to Live Vegas Markets
Check the Live Multi-Sport Odds Board for current spreads, moneylines, and totals across NFL, NCAAF, NBA,NCAAB, MLB, NHL, UFC, Soccer, and Tennis, or explore our Betting School curriculum for deeper handicapping lessons.