Free calculator
Odds converter
Type odds in any one format and read the rest instantly: American, decimal, fractional, and the implied probability, all from a single number.
Input format
For information only. Not betting advice.
How it works
Every odds format describes the same thing: how much a winning bet returns, and the probability the book is implying. Decimal odds are the anchor. They are the total return on a 1 unit stake, so decimal 2.50 returns 2.50 for every 1 staked.
From the decimal odds the rest follow. Implied probability is 1 divided by the decimal odds. Fractional odds are the profit over the stake, so decimal 2.50 is a profit of 1.50 per 1 staked, which reduces to 3/2.
American to decimal: a positive price p gives 1 plus p over 100. A negative price gives 1 plus 100 over the absolute value of p. Numbers between -100 and +100 do not describe a real price, so the converter treats them as invalid.
Worked example
At American -110, the decimal odds are 1 + 100/110 = 1.9091, the implied probability is 1 / 1.9091 = 52.38%, and the fraction is 10/11. At +150 the decimal odds are 1 + 150/100 = 2.50, the implied probability is 40.00%, and the fraction is 3/2.
Questions
- What is implied probability?
- It is the chance of winning that a price implies, before any margin is removed. It is 1 divided by the decimal odds, so -110 implies 52.38%. Because the book builds in a margin, the two sides of a market add up to more than 100%.
- Why do American odds skip the range between -100 and +100?
- American odds describe profit against a 100 unit baseline, so even money meets at +100 and -100, both equal to decimal 2.00. Values inside that range do not describe a real price, so the converter marks them invalid.
- How do you turn decimal odds into a fraction?
- Fractional odds are the profit over the stake, which is the decimal odds minus 1. The tool reduces that to the simplest whole-number fraction, so 1.9091 becomes 10/11 and 2.50 becomes 3/2.
- Are these the real odds I will get?
- The conversions are exact. Whether a book offers a given price is up to the book, and prices move. This tool only changes the format, it does not find or predict odds.