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Free odds converter

Decimal, fractional and American, bidirectional, real-time, with the implied probability shown.

Odds Converter

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European format · payout including stake
UK format · profit-to-stake (e.g. 5/2)
US format · +underdog / −favourite
Implied probabilityFavourite
50.00%≈ 1 in 2.00
Implied probability assumes a fair book (no overround). Bookmakers price below this.
Common odds
How it works: Decimal 2.50 = 3/2 = +150 = 40% implied probability. Decimal includes your stake; fractional shows pure profit-to-stake. American odds use + for underdogs (profit on £100) and − for favourites (stake to win £100).

How to convert betting odds

Type a value into any of the three input boxes, decimal, fractional or American. The other two update instantly with the equivalent prices, and the implied probability card below shows the bookmaker's view of the underlying chance, as both a percentage and a visual bar. The Common Odds quick-pick chips load standard UK prices into all three fields with one tap, handy as a sanity check on whether your typed value reads right.

What the three odds formats actually mean

All three formats encode the same number: the bookmaker's view of how likely an outcome is, expressed differently for different audiences. Decimal is the modern standard everywhere except the UK retail high street, multiply the price by your stake to see total return (a £10 bet at 2.50 returns £25). Fractional is the UK pub-and-paper tradition: the numerator is profit per units of the denominator (5/2 means £5 profit per £2 staked). American is the US sportsbook format: positive numbers show profit per $100 staked, negative numbers show the stake needed to win $100.

The conversion maths is fixed and exact, no rounding, no operator-specific tweak. What varies is the bookmaker's margin baked into the price they actually offer you, which is what bookmaker pricing actually reveals about probability , the full cornerstone reference covers it.

Common UK odds at a glance

Every price a UK punter routinely encounters, in all three formats, with the implied probability worked out.

FractionalDecimalAmericanImplied probability
Evens (1/1)2.00+10050.00%
6/42.50+15040.00%
7/42.75+17536.36%
2/13.00+20033.33%
5/23.50+25028.57%
3/14.00+30025.00%
7/24.50+35022.22%
4/15.00+40020.00%
9/25.50+45018.18%
5/16.00+50016.67%
10/111.00+10009.09%
20/121.00+20004.76%

Related tools and guides

Common questions

What is implied probability?
Implied probability is the bookmaker's view of how likely an outcome is, expressed as a percentage. The formula is 1 ÷ decimal odds. A 2.50 horse has an implied probability of 40%; a 5.00 horse, 20%. Across all the outcomes in a market, the implied probabilities sum to slightly more than 100%, the difference is the bookmaker's margin.
How do I convert 5/2 to decimal?
Add 1 to the fractional ratio. 5/2 = 2.5 + 1 = 3.50 decimal. The same horse pays out at +250 in American format. The implied probability is 1 ÷ 3.50 = 28.57%.
Is +150 the same as 5/2?
No. +150 means $150 profit on a $100 stake, which is 1.5 + 1 = 2.50 decimal, equivalent to 3/2 fractional. The American equivalent of 5/2 (3.50 decimal) is +250. The converter handles this, type +150 and it shows 2.50 / 3/2 / 60.0% implied.
Why do UK bookmakers still quote in fractions?
Tradition, mostly. Fractional notation predates decimal pricing by a couple of centuries in UK racing and is still what most punters mentally read. The on-course bookies and high-street shops display fractional by default; online operators usually show all three. The underlying maths is identical regardless of which format the price is written in.
Are these conversions exact?
Yes, to the precision your input allows. Fractional-to-decimal and American-to-decimal are exact closed-form conversions, not approximations. Displayed values are rounded to two decimal places for readability, but the underlying calculation is full-precision.

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