Decimal odds and fractional odds describe the same price in two ways. Decimals are common in Europe and on betting exchanges. Fractions are the traditional British and Irish style, and they are still what you see on a racecourse board. If you need to move from one to the other, the table below does it for 373 common prices, from 1.01 to 1001.
How to convert decimal to fractional odds
The rule takes one step. Subtract 1 from the decimal price and read the result as a fraction of 1.
- 3.00 becomes 2.00, so the fractional price is 2/1.
- 2.50 becomes 1.50, which is 3/2.
- 1.50 becomes 0.50, which is 1/2.
- 11.00 becomes 10.00, so 10/1.
Going the other way, divide the top of the fraction by the bottom and add 1. A price of 9/4 is 2.25 plus 1, so 3.25 in decimals.
The conversion table
The table lists the decimal price on the left of each pair and the fractional price on the right. Fractional prices are shown on the traditional ladder bookmakers use, so many decimals map to the closest standard fraction instead of an exact one.
| 1.01 – 1/100 | 2.52 – 6/4 | 51.00 – 50/1 |
| 1.02 – 1/50 | 2.54 – 6/4 | 55.00 – 54/1 |
| 1.03 – 1/33 | 2.56 – 8/5 | 60.00 – 59/1 |
| 1.04 – 1/25 | 2.58 – 8/5 | 61.00 – 60/1 |
| 1.05 – 1/20 | 2.60 – 8/5 | 65.00 – 64/1 |
| 1.06 – 1/17 | 2.62 – 13/8 | 66.00 – 65/1 |
| 1.07 – 1/14 | 2.64 – 13/8 | 67.00 – 66/1 |
| 1.08 – 1/12 | 2.66 – 13/8 | 70.00 – 69/1 |
| 1.09 – 1/11 | 2.68 – 13/8 | 71.00 – 70/1 |
| 1.10 – 1/10 | 2.70 – 7/4 | 75.00 – 74/1 |
| 1.11 – 1/9 | 2.72 – 7/4 | 76.00 – 75/1 |
| 1.12 – 1/8 | 2.74 – 7/4 | 80.00 – 79/1 |
| 1.13 – 2/15 | 2.76 – 7/4 | 81.00 – 80/1 |
| 1.14 – 1/7 | 2.78 – 9/5 | 85.00 – 84/1 |
| 1.15 – 2/13 | 2.80 – 9/5 | 90.00 – 89/1 |
| 1.16 – 2/13 | 2.82 – 9/5 | 91.00 – 90/1 |
| 1.17 – 1/6 | 2.84 – 15/8 | 95.00 – 94/1 |
| 1.18 – 2/11 | 2.86 – 15/8 | 100.00 – 99/1 |
| 1.19 – 2/11 | 2.88 – 15/8 | 101.00 – 100/1 |
| 1.20 – 1/5 | 2.90 – 15/8 | 110.00 – 109/1 |
| 1.21 – 1/5 | 2.92 – 15/8 | 111.00 – 110/1 |
| 1.22 – 2/9 | 2.94 – 2/1 | 120.00 – 119/1 |
| 1.23 – 2/9 | 2.96 – 2/1 | 126.00 – 125/1 |
| 1.24 – 1/4 | 2.98 – 2/1 | 130.00 – 129/1 |
| 1.25 – 1/4 | 3.00 – 2/1 | 140.00 – 139/1 |
| 1.26 – 1/4 | 3.05 – 2/1 | 150.00 – 149/1 |
| 1.27 – 1/4 | 3.10 – 85/40 | 151.00 – 150/1 |
| 1.28 – 2/7 | 3.15 – 11/5 | 160.00 – 159/1 |
| 1.29 – 2/7 | 3.20 – 11/5 | 170.00 – 169/1 |
| 1.30 – 3/10 | 3.25 – 9/4 | 176.00 – 175/1 |
| 1.31 – 3/10 | 3.30 – 9/4 | 180.00 – 179/1 |
| 1.32 – 1/3 | 3.35 – 12/5 | 190.00 – 189/1 |
| 1.33 – 1/3 | 3.40 – 12/5 | 200.00 – 199/1 |
| 1.34 – 1/3 | 3.45 – 5/2 | 201.00 – 200/1 |
| 1.35 – 1/3 | 3.50 – 5/2 | 210.00 – 209/1 |
| 1.36 – 4/11 | 3.55 – 5/2 | 220.00 – 219/1 |
| 1.37 – 4/11 | 3.60 – 13/5 | 226.00 – 225/1 |
| 1.38 – 4/11 | 3.65 – 13/5 | 230.00 – 229/1 |
| 1.39 – 2/5 | 3.70 – 11/4 | 240.00 – 239/1 |
| 1.40 – 2/5 | 3.75 – 11/4 | 250.00 – 249/1 |
| 1.41 – 2/5 | 3.80 – 14/5 | 251.00 – 250/1 |
| 1.42 – 2/5 | 3.85 – 14/5 | 260.00 – 259/1 |
| 1.43 – 4/9 | 3.90 – 3/1 | 270.00 – 269/1 |
| 1.44 – 4/9 | 3.95 – 3/1 | 276.00 – 275/1 |
| 1.45 – 4/9 | 4.00 – 3/1 | 280.00 – 279/1 |
| 1.46 – 40/85 | 4.10 – 3/1 | 290.00 – 289/1 |
| 1.47 – 40/85 | 4.20 – 16/5 | 300.00 – 299/1 |
| 1.48 – 40/85 | 4.30 – 10/3 | 301.00 – 300/1 |
| 1.49 – 1/2 | 4.40 – 7/2 | 310.00 – 309/1 |
| 1.50 – 1/2 | 4.50 – 7/2 | 320.00 – 319/1 |
| 1.51 – 1/2 | 4.60 – 7/2 | 330.00 – 329/1 |
| 1.52 – 8/15 | 4.70 – 7/2 | 340.00 – 339/1 |
| 1.53 – 8/15 | 4.80 – 4/1 | 350.00 – 349/1 |
| 1.54 – 8/15 | 4.90 – 4/1 | 351.00 – 350/1 |
| 1.55 – 8/15 | 5.00 – 4/1 | 360.00 – 359/1 |
| 1.56 – 4/7 | 5.10 – 4/1 | 370.00 – 369/1 |
| 1.57 – 4/7 | 5.20 – 4/1 | 380.00 – 379/1 |
| 1.58 – 4/7 | 5.30 – 9/2 | 390.00 – 389/1 |
| 1.59 – 4/7 | 5.40 – 9/2 | 400.00 – 399/1 |
| 1.60 – 8/13 | 5.50 – 9/2 | 401.00 – 400/1 |
| 1.61 – 8/13 | 5.60 – 9/2 | 410.00 – 409/1 |
| 1.62 – 5/8 | 5.70 – 9/2 | 420.00 – 419/1 |
| 1.63 – 5/8 | 5.80 – 5/1 | 430.00 – 429/1 |
| 1.64 – 5/8 | 5.90 – 5/1 | 440.00 – 439/1 |
| 1.65 – 4/6 | 6.00 – 5/1 | 450.00 – 449/1 |
| 1.66 – 4/6 | 6.20 – 5/1 | 460.00 – 459/1 |
| 1.67 – 4/6 | 6.40 – 11/2 | 470.00 – 469/1 |
| 1.68 – 4/6 | 6.60 – 11/2 | 480.00 – 479/1 |
| 1.69 – 5/7 | 6.80 – 6/1 | 490.00 – 489/1 |
| 1.70 – 5/7 | 7.00 – 6/1 | 500.00 – 499/1 |
| 1.71 – 5/7 | 7.20 – 6/1 | 501.00 – 500/1 |
| 1.72 – 8/11 | 7.40 – 13/2 | 510.00 – 509/1 |
| 1.73 – 8/11 | 7.60 – 13/2 | 520.00 – 519/1 |
| 1.74 – 8/11 | 7.80 – 7/1 | 530.00 – 529/1 |
| 1.75 – 8/11 | 8.00 – 7/1 | 540.00 – 539/1 |
| 1.76 – 8/11 | 8.20 – 7/1 | 550.00 – 549/1 |
| 1.77 – 4/5 | 8.40 – 15/2 | 560.00 – 559/1 |
| 1.78 – 4/5 | 8.60 – 15/2 | 570.00 – 569/1 |
| 1.79 – 4/5 | 8.80 – 8/1 | 580.00 – 579/1 |
| 1.80 – 4/5 | 9.00 – 8/1 | 590.00 – 589/1 |
| 1.81 – 4/5 | 9.20 – 8/1 | 600.00 – 599/1 |
| 1.82 – 4/5 | 9.40 – 17/2 | 610.00 – 609/1 |
| 1.83 – 4/5 | 9.60 – 17/2 | 620.00 – 619/1 |
| 1.84 – 5/6 | 9.80 – 9/1 | 630.00 – 629/1 |
| 1.85 – 5/6 | 10.00 – 9/1 | 640.00 – 639/1 |
| 1.86 – 5/6 | 10.50 – 19/2 | 650.00 – 649/1 |
| 1.87 – 5/6 | 11.00 – 10/1 | 660.00 – 659/1 |
| 1.88 – 10/11 | 11.50 – 21/2 | 670.00 – 669/1 |
| 1.89 – 10/11 | 12.00 – 11/1 | 680.00 – 679/1 |
| 1.90 – 10/11 | 12.50 – 23/2 | 690.00 – 689/1 |
| 1.91 – 10/11 | 13.00 – 12/1 | 700.00 – 699/1 |
| 1.92 – 10/11 | 13.50 – 25/2 | 710.00 – 709/1 |
| 1.93 – 10/11 | 14.00 – 13/1 | 720.00 – 719/1 |
| 1.94 – 20/21 | 14.50 – 27/2 | 730.00 – 729/1 |
| 1.95 – 20/21 | 15.00 – 14/1 | 740.00 – 739/1 |
| 1.96 – 20/21 | 15.50 – 29/2 | 750.00 – 749/1 |
| 1.97 – 20/21 | 16.00 – 15/1 | 751.00 – 750/1 |
| 1.98 – 1/1 | 16.50 – 31/2 | 760.00 – 759/1 |
| 1.99 – 1/1 | 17.00 – 16/1 | 770.00 – 769/1 |
| 2.00 – 1/1 | 17.50 – 33/2 | 780.00 – 779/1 |
| 2.02 – 1/1 | 18.00 – 17/1 | 790.00 – 789/1 |
| 2.04 – 21/20 | 18.50 – 35/2 | 800.00 – 799/1 |
| 2.06 – 21/20 | 19.00 – 18/1 | 810.00 – 809/1 |
| 2.08 – 11/10 | 19.50 – 37/2 | 820.00 – 819/1 |
| 2.10 – 11/10 | 20.00 – 19/1 | 830.00 – 829/1 |
| 2.12 – 11/10 | 21.00 – 20/1 | 840.00 – 839/1 |
| 2.14 – 11/10 | 22.00 – 21/1 | 850.00 – 849/1 |
| 2.16 – 6/5 | 23.00 – 22/1 | 860.00 – 859/1 |
| 2.18 – 6/5 | 24.00 – 23/1 | 870.00 – 869/1 |
| 2.20 – 6/5 | 26.00 – 25/1 | 880.00 – 879/1 |
| 2.22 – 6/5 | 28.00 – 27/1 | 890.00 – 889/1 |
| 2.24 – 5/4 | 29.00 – 28/1 | 900.00 – 899/1 |
| 2.26 – 5/4 | 30.00 – 29/1 | 910.00 – 909/1 |
| 2.28 – 5/4 | 31.00 – 30/1 | 920.00 – 919/1 |
| 2.30 – 5/4 | 32.00 – 31/1 | 930.00 – 929/1 |
| 2.32 – 11/8 | 34.00 – 33/1 | 940.00 – 939/1 |
| 2.34 – 11/8 | 36.00 – 35/1 | 950.00 – 949/1 |
| 2.36 – 11/8 | 38.00 – 37/1 | 960.00 – 959/1 |
| 2.38 – 11/8 | 40.00 – 39/1 | 970.00 – 969/1 |
| 2.40 – 7/5 | 41.00 – 40/1 | 980.00 – 979/1 |
| 2.42 – 7/5 | 42.00 – 41/1 | 990.00 – 989/1 |
| 2.44 – 7/5 | 44.00 – 43/1 | 1000.00 – 999/1 |
| 2.46 – 6/4 | 46.00 – 45/1 | 1001.00 – 1000/1 |
| 2.48 – 6/4 | 48.00 – 47/1 | |
| 2.50 – 6/4 | 50.00 – 49/1 |
Why some rows look rounded
Take 2.52. Subtracting 1 gives 1.52, which is not a neat fraction. The nearest standard price on the ladder is 6/4, which is 1.50, so that is what the table shows. The next few prices, 2.52 and 2.54 on one side and 2.56 to 2.60 on the other, land on 6/4 and 8/5 for the same reason. Bookmakers price in a limited set of fractions, and each decimal sits between two of them.
If you need the exact fraction, use the rule above and reduce it. 2.52 minus 1 is 1.52, which is 38/25.
Decimal odds and probability
A decimal price converts directly into the probability it implies: divide 1 by the price. A price of 4.00 implies 25%, 2.00 implies 50% and 10.00 implies 10%. Add the implied probabilities for every runner in a race and the total comes to more than 100%. The excess is the bookmaker’s margin, and it is the reason probabilities from odds always overstate the true chances a little.
How racing data stores odds
When you work with results data, prices are almost always decimals, because decimals are easier to store and calculate. In our UK records the starting price is held as a decimal number, so a horse that went off at 9/2 appears as 5.5. Hong Kong records carry win and place odds in decimals too, for example 5.5 or 7.3.
Remember that a starting price is only settled at the off, so it belongs on the results side of a dataset, not in the information known when runners are declared. Our data model guide explains the difference between the two, and feature engineering for horse racing shows how to avoid using it by mistake.
A converter is only as good as the prices you feed it, so check the format of whatever you are pulling odds from. In our files they are decimals, which a quick look at the table above will confirm. The prices sit next to each race in the horse racing datasets and the API.
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