Odds Converter

Different books and countries quote odds in different formats. This converts any price into all four at once — decimal, American, fractional, and the implied probability behind it.

Input format

Your odds

2.50

Decimal

+150

American

3/2

Fractional

40.0%

Implied probability

HOW IT WORKS

The method.

1

What it does

Enter a price in any format and read it in every other, plus the implied probability (1 ÷ decimal odds) — the real number you should compare against your own estimate.

2

Why implied probability matters

Formats are cosmetic; implied probability is the signal. If your estimate of an outcome beats the book's implied probability, you have an edge — regardless of how the odds are written.

3

Reading the margin

Add up the implied probabilities of every outcome in a market: anything over 100% is the book's margin (the “vig”). Lower combined totals mean sharper, better-value books.

Educational only — not betting advice. Calculators and simulations are illustrative; past results and simulated outcomes don’t guarantee future returns. Bet responsibly.

FAQ

Questions, answered.

For decimal odds of 2.00 or higher, American odds = (decimal − 1) × 100. Below 2.00, American odds = −100 ÷ (decimal − 1). This converter does it both ways instantly, along with fractional and implied probability.

Implied probability is the chance an outcome must have for the odds to be fair: 1 ÷ decimal odds, as a percentage. Decimal odds of 2.50 imply a 40% chance. It's the real number to compare against your own estimate.

Add up the implied probabilities of every outcome in a market. Anything over 100% is the bookmaker's margin (the 'vig' or 'juice'). The lower the total, the sharper and better-value the book.