- Maths reviewed by Josh Miller
- Tested by Diana Westfield
Decimal to fractional odds is a one-step job: knock 1 off the decimal and turn what’s left into a fraction. 2.75 becomes 1.75, which is 7/4. The free CasinoCalcs converter above does that for any price and then rounds it to the fraction a bookmaker would actually print, because nobody in a betting shop has ever seen 69/50.
Decimal to fractional odds, step by step
Take 3.50. Subtract the 1 and you’ve got 2.50, or two and a half to one. Written as a fraction with whole numbers, that’s 5/2. Now try 1.80: 0.80 is four fifths, so 4/5. The 1 you took off is your stake coming back. Decimal odds include it, fractions don’t.
That’s the whole trick. The fiddly part is when the decimal has been rounded.
Why 2.38 is 11/8 and not 69/50
Exchanges and most apps show two decimal places. 11/8 is really 2.375, so it gets rounded up to 2.38. Do the maths on 2.38 and you get 1.38, or 69/50, which is correct but useless. The converter snaps it back to the nearest price on the standard ladder instead. Same story with 1.91: it’s 10/11 with the decimals chopped, not 91/100.
The prices that catch people out most are 1.62 (8/13), 1.73 (8/11), 2.62 (13/8), 2.88 (15/8) and 4.33 (10/3).
Decimal to fractional odds chart
| Decimal | Fractional | Implied chance |
|---|---|---|
| 1.20 | 1/5 | 83.3% |
| 1.25 | 1/4 | 80.0% |
| 1.33 | 1/3 | 75.2% |
| 1.40 | 2/5 | 71.4% |
| 1.50 | 1/2 | 66.7% |
| 1.62 | 8/13 | 61.7% |
| 1.67 | 4/6 | 59.9% |
| 1.73 | 8/11 | 57.8% |
| 1.80 | 4/5 | 55.6% |
| 1.83 | 5/6 | 54.6% |
| 1.91 | 10/11 | 52.4% |
| 2.00 | evens | 50.0% |
| 2.10 | 11/10 | 47.6% |
| 2.20 | 6/5 | 45.5% |
| 2.25 | 5/4 | 44.4% |
| 2.38 | 11/8 | 42.0% |
| 2.50 | 6/4 | 40.0% |
| 2.62 | 13/8 | 38.2% |
| 2.75 | 7/4 | 36.4% |
| 2.88 | 15/8 | 34.7% |
| 3.00 | 2/1 | 33.3% |
| 3.25 | 9/4 | 30.8% |
| 3.50 | 5/2 | 28.6% |
| 3.75 | 11/4 | 26.7% |
| 4.00 | 3/1 | 25.0% |
| 4.33 | 10/3 | 23.1% |
| 4.50 | 7/2 | 22.2% |
| 5.00 | 4/1 | 20.0% |
| 5.50 | 9/2 | 18.2% |
| 6.00 | 5/1 | 16.7% |
| 7.00 | 6/1 | 14.3% |
| 8.00 | 7/1 | 12.5% |
| 9.00 | 8/1 | 11.1% |
| 11.00 | 10/1 | 9.1% |
| 13.00 | 12/1 | 7.7% |
| 17.00 | 16/1 | 5.9% |
| 21.00 | 20/1 | 4.8% |
| 26.00 | 25/1 | 3.8% |
| 34.00 | 33/1 | 2.9% |
| 51.00 | 50/1 | 2.0% |
Anything at or above 2.00 is odds-against: the fraction has the bigger number on top. Below 2.00 it flips, and you’re laying more than you win.
When the fraction is easier
Fractions are handy for one thing: seeing the profit straight away. 7/4 means £7 profit for every £4 staked. On a £20 bet that’s £35 profit, £55 back. If you’re doing each way maths in your head, fractions are also what place terms are written in (1/5 the odds and so on), so it helps to have both. The each way calculator does that part for you.
Going the other way? Use the fractional to decimal odds converter, or the full odds converter if you want American odds in the same place.
Odds tell you the price, not the chance you’re right. BeGambleAware.org is free and confidential if betting stops being fun.