- Maths reviewed by Josh Miller
- Tested by Diana Westfield
Fractional to American odds is easiest when the fraction is odds-against: multiply it by 100 and put a plus in front. 5/2 is 2.5, times 100, so +250. Odds-on fractions go negative: divide −100 by the fraction, so 4/6 (0.667) becomes −150. The free CasinoCalcs converter handles both, and evens comes out as +100.
Fractional to American odds in two lines
Fraction 1/1 or bigger: American = +fraction × 100 (7/4 → +175) Fraction under 1/1: American = −100 ÷ fraction (2/5 → −250)
A neat pattern falls out of this. Flip an odds-on fraction and you get the American number without the zero: 4/6 flipped is 6/4, which is 1.5, and the American is −150. 2/5 flipped is 5/2, and the American is −250.
Fractional to American odds chart
| Fractional | American | Decimal |
|---|---|---|
| 1/5 | −500 | 1.20 |
| 1/3 | −300 | 1.33 |
| 1/2 | −200 | 1.50 |
| 4/6 | −150 | 1.67 |
| 4/5 | −125 | 1.80 |
| 10/11 | −110 | 1.91 |
| evens (1/1) | +100 | 2.00 |
| 6/5 | +120 | 2.20 |
| 6/4 | +150 | 2.50 |
| 7/4 | +175 | 2.75 |
| 2/1 | +200 | 3.00 |
| 5/2 | +250 | 3.50 |
| 3/1 | +300 | 4.00 |
| 4/1 | +400 | 5.00 |
| 5/1 | +500 | 6.00 |
| 7/1 | +700 | 8.00 |
| 10/1 | +1000 | 11.00 |
| 16/1 | +1600 | 17.00 |
| 20/1 | +2000 | 21.00 |
| 33/1 | +3300 | 34.00 |
| 50/1 | +5000 | 51.00 |
| 100/1 | +10000 | 101.00 |
Where this comes up
Mostly when a UK or Irish price needs comparing with a North American line. A horse at 7/4 in Britain and +175 on a Canadian site is the same price exactly. Tennis and golf are the other ones, because the same event gets priced in both formats on the same day. 10/11 is the classic: it’s −110, the standard two-way price.
For the reverse there’s the American to fractional converter. If you want decimals in the mix, the odds converter shows all three side by side.
Converting a price doesn’t change the odds of it winning. BeGambleAware.org is there, free, if gambling is causing problems.