Odds converter
Decimal · Fractional · American · Implied
Convert between decimal, fractional, American and implied probability — instantly.
What does an odds converter do?
Different parts of the world quote betting odds differently. UK bookmakers use fractional odds (3/2, 5/1). European bookmakers use decimal (2.50, 6.00). American sportsbooks use moneyline (+150, -200). And every odds figure secretly contains an implied probability — the bookmaker's estimate of how likely the outcome is. An odds converter translates between all four so you can compare offers from any source without doing math in your head. Once converted, use Value Bet finder to spot mispriced markets, or Margin calculator to assess bookmaker quality.
See also: Kelly criterion, Bookmaker margin calculator, Value bet finder
How to use this calculator
- 1Pick whichever format you have — decimal, fractional, American or implied %
- 2Type the odds in. The other three formats update automatically as you type.
- 3Enter your intended stake at the bottom to see the total payout (stake + winnings) and net profit.
Example: comparing two bookmakers
Bookmaker A offers 2.50 decimal on Liverpool to win. Bookmaker B offers +145 American on the same outcome. Which is better? Type 2.50 into the decimal box — you'll see +150 American. So Bookmaker A's 2.50 is better than Bookmaker B's +145 (which equals 2.45 decimal). The difference looks tiny but over 500 bets at €100 each it's €2,500 in expected value.
The formulas behind it
If you want to do it by hand:
- Fractional from decimal: (decimal − 1) expressed as a fraction. So 2.50 → 1.50/1 → 3/2.
- American from decimal: if decimal ≥ 2.00, American = (decimal − 1) × 100. If decimal < 2.00, American = −100 / (decimal − 1). So 2.50 → +150 and 1.50 → −200.
- Implied probability from decimal: 1 / decimal × 100. So 2.50 → 40%. This is what the bookmaker thinks the chance is (including their margin).
When should I use it?
- Comparing offers from US, UK and European bookmakers in the same market
- Converting a tipster's pick into your local format
- Checking implied probability — if you think the real probability is higher, you've found a value bet
- Calculating exact payout before placing a bet to make sure you understand the risk
Frequently asked questions
What is the Odds converter calculator?
Different parts of the world quote betting odds differently. UK bookmakers use fractional odds (3/2, 5/1).
How does the Odds converter calculator work in practice?
Bookmaker A offers 2.50 decimal on Liverpool to win. Bookmaker B offers +145 American on the same outcome. Which is better? Type 2.50 into the decimal box — you'll see +150 American. So Bookmaker A's 2.50 is better than Bookmaker B's +145 (which equals 2.45 decimal). The difference looks tiny but over 500 bets at €100…
When should I use the Odds converter calculator?
Comparing offers from US, UK and European bookmakers in the same market. Converting a tipster's pick into your local format. Checking implied probability — if you think the real probability is higher, you've found a value bet.