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Tool · Formats

Odds Format Converter

Convert instantly between Decimal, Fractional, American odds formats and Implied Probability. Understand and compare odds displayed in different formats.

Presets
On a £1 stake
Decimal
2.00
Profit
£1.00
Breakeven win-rate
50.00%
Implied prob.
50.00%
How to use this tool
  1. Enter a value in any odds field (Decimal, Fractional, American or Implied Probability).
  2. The equivalent values will update automatically.
  3. Use the stake breakdown to understand the potential profit.

Frequently Asked Questions

What do Fractional odds like 5/2 mean?

Fractional odds show the potential profit compared with the stake. For example, 5/2 means you would make £5 profit for every £2 staked. A £20 bet would return £70 in total (£50 profit plus your £20 stake). The equivalent Decimal odds are 3.50 (5/2 + 1), with an implied probability of 28.57% (1/3.50).

Enter your Fractional odds in our tool to instantly see the Decimal, American and implied probability equivalents.

How do I convert American odds to Decimal odds?

American odds convert differently depending on whether they are positive or negative.

Positive odds show the potential profit from a £100 stake. For example, +200 means a £100 bet would return £300 in total (£200 profit plus your £100 stake). The equivalent Decimal odds are 3.00, with an implied probability of 33.33% (1/3.00).

Negative odds show the stake required to make a £100 profit. For example, -200 means a £200 bet would return £300 in total (£100 profit plus your £200 stake). The equivalent Decimal odds are 1.50, with an implied probability of 66.67% (1/1.50).

Enter your American odds in our tool to instantly see the Decimal, Fractional and implied probability equivalents.

Why do bookmakers use different odds formats?

Different regions and betting platforms use different ways of displaying odds. Decimal odds are common in Europe, Fractional odds are popular in the UK, and American odds are mainly used in the US. They all represent the same underlying price, just displayed in different formats.

Use our converter to compare the same odds regardless of which format they are displayed in.

Which odds format should I use?

There is no single "best" odds format. Decimal odds are often easiest for calculations and comparing bookmakers, but different formats are popular in different regions. The important thing is to convert between formats consistently when comparing odds or calculating returns.

Use our converter to do this instantly.

What is implied probability in betting odds?

Implied probability shows the chance of an outcome according to the odds. For example, Decimal odds of 2.00 imply a 50% probability.

Bettors often compare their own assessment of an outcome's probability with the implied probability from the odds to identify potential value. Many betting concepts, including Expected Value (EV) and Kelly Criterion, are based on comparing estimated probabilities with implied probabilities.

Enter the odds in our converter to see the implied probability instantly, or enter a probability to see the equivalent odds.

Formulas
Decimal ↔ Implied: p = 1 / d, d = 1 / p
Decimal → American: if d ≥ 2: A = +100·(d−1); else A = −100/(d−1)
American → Decimal: if A ≥ +100: d = A/100 + 1; if A ≤ −100: d = 100/|A| + 1
Fractional: d = 1 + num/den. Converting decimal → fractional uses the best rational approximation with denominator ≤ 1000 (continued fractions).

Information only. Check all calculations before placing bets. Odds and market conditions may change. Bet Tools HQ accepts no responsibility for losses arising from reliance on these results.