King's Top Tips
Odds Converter
Free instant odds converter — switch between fractional, decimal and American (moneyline) formats and see the implied probability of any price.
What this converter does
Instantly switch between fractional, decimal and American (moneyline) odds, and see the implied probability for any price. Type into any field — the other three update automatically.
How the maths works
- Decimal → implied probability: 1 ÷ decimal odds × 100. Example: 2.50 → 40%.
- Fractional → decimal: (numerator ÷ denominator) + 1. Example: 6/4 → 2.50.
- American positive → decimal: (odds ÷ 100) + 1. Example: +150 → 2.50.
- American negative → decimal: (100 ÷ |odds|) + 1. Example: -200 → 1.50.
Why you'd use it
Most UK bookmakers default to fractional, sharp markets to decimal, and US books to American. Converting at a glance lets you line-shop across formats without losing your edge. Read our odds guide for a deeper walkthrough of implied probability and bookmaker margins.
Frequently asked questions
What is implied probability?
Implied probability is the bookmaker's stated chance of an outcome, calculated as 1 / decimal odds × 100. For example, decimal odds of 2.00 carry an implied probability of 50%. Use the converter to spot prices where your own estimated probability is higher — that is the definition of a value bet.
How do I convert fractional odds to decimal?
Divide the numerator by the denominator and add 1. For example, 5/2 becomes 2.50 + 1 = 3.50. The converter does this instantly for fractional, decimal and American formats.
Why do American odds use + and − signs?
Positive American odds (e.g. +200) show the profit on a 100-unit stake. Negative odds (e.g. −150) show the stake required to win 100 units. The converter normalises both into decimal so you can compare prices across markets quickly.