Odds Converter for Every Format
Type a price into any one box and the other three redraw to match, decimal, fractional, American and Hong Kong, with the implied probability worked out alongside.
Convert a price, any format
Type a number into any one box below, decimal, fractional, American or Hong Kong, and the rest redraw to match it, along with the implied probability. Nothing you type is sent anywhere; the sums run in your own browser.
An odds converter turns one betting price into decimal, fractional, American and Hong Kong format, and shows the implied probability behind it. Type a number into any of the four boxes above and the others update to match. On a bookmaker's board that is usually where the story stops. On Betfair Exchange the price you see was agreed between two customers, not set by an operator, and exchange commission is due only on net winnings in a market, never on a loss. This tool does the arithmetic. It does not say whether 1.95 is a fair price, and it does not say what you will actually be paid: read the limits below before you act on a converted number.
Reading the four boxes
The boxes sync both ways: edit any one of decimal, fractional, American or Hong Kong, and the other three redraw to match it, rounded to two decimal places where that applies (the site's usual precision for a price). Whichever box you are actually typing in is left alone, so a half-finished "1.9" is never overwritten mid-keystroke.
Decimal is the exchange's native format: multiply it by a stake for the return, stake included. Fractional is the traditional British board price, profit over stake, so 19/20 means risking £20 to profit £19, not £19 total. American, or moneyline, flips sign at evens: plus is the profit on a 100 unit stake, minus is the stake needed to profit 100, and the convention only ever shows +100, never -100, for evens, which the tool follows even if you type the other sign. Hong Kong odds are the same profit per stake as fractional, just written as a decimal: 0.95 and 19/20 are one price in two alphabets, and people mix the two up constantly (harmless, but worth saying once).
I would not bother memorising the American sign rule under pressure. Read the two boxes side by side instead, and the tool tells you which side of evens you are on.
Two prices, worked through
Two examples, checked by hand.
1.95 is an odds-on favourite: fractional 19/20, risking £20 to profit £19; American -105, staking £105 to profit £100; Hong Kong 0.95; implied probability about 51.3%.
4.33 is the underdog in the same kind of match: fractional 333/100, an unusually specific reduction most boards round away (the arithmetic does not care what looks neat); American +333, a £100 stake profiting £333; Hong Kong 3.33; implied probability about 23.1%.
| Decimal | Fractional | American | Hong Kong | Implied probability |
|---|---|---|---|---|
| 1.95 | 19/20 | -105 | 0.95 | 51.3% |
| 4.33 | 333/100 | +333 | 3.33 | 23.1% |
| 1.40 | 2/5 | -250 | 0.40 | 71.4% |
| 2.00 | 1/1 | +100 | 1.00 | 50.0% |
1.40 reduces to a tidy 2/5, which most prices do not manage. 2.00 is the evens boundary: American sits at exactly +100 and never crosses into negative territory, whichever way you typed it in. On a £10 stake, 1.95 returns £19.50, £9.50 profit before exchange commission; 4.33 returns £43.30, £33.30 profit before exchange commission. Read those as "if it wins", not as an edge: a converter has no opinion on whether either price is worth backing.
Same price. Four spellings. One probability.
Where the numbers stop
A converted number is still the same price, relabelled: it says nothing about value. And on Betfair Exchange that number was never fixed by an operator, it is agreed between two customers, matched back against lay, with exchange commission due only on net winnings in a market, never on a loss. What a market's built-in margin costs you is a separate sum.
Converting down and back up is not always lossless, either. A price with more precision than a board shows, say 1.9389 rather than a quoted 1.95, converts to American as -107; convert -107 back and the decimal reads 1.93, not 1.9389. Not a bug: a whole-number American price, or a fraction already reduced, cannot carry four decimal places back.
I would not trust a converted price more than the one it came from. Convert a fraction or a moneyline once, note the decimal, and work from that copy rather than converting back and forth.
Prices convert the same way whether the market is a back and lay exchange or a fixed bookmaker board. Format matters most when comparing: splitting a stake across two prices, or arbitrage betting across two bookmakers, both need every price read the same way first. Reaching an exchange is usually the harder part: which route fits you is a five-question sort, getting in, step by step, covers the account, and the broker comparison lines up the alternatives. The other calculators all assume a decimal price to start from.
Questions people ask
How do I convert decimal odds to fractional, American and Hong Kong by hand?
Fractional: subtract 1 and reduce to lowest terms (1.95 minus 1 is 0.95, or 19/20). American: at 2.00 or higher, subtract 1 and multiply by 100 for a plus figure; below 2.00, divide 100 by (decimal minus 1) and make it negative. Hong Kong is simply decimal minus 1.
What is implied probability, and how do I get it from any format?
1 divided by the decimal odds, as a percentage: 1.95 implies about 51.3%. From another format, convert to decimal first, then divide 1 by that. It is "implied" because it comes from the price alone, not from any assessment of the real chance.
Does this converter cover every odds format there is?
No, and it is worth saying plainly: decimal, fractional, American and Hong Kong, the four named in the title. Indonesian and Malaysian formats are not included. They follow a similar idea, profit per stake written another way, but a different scale, so treat them as a separate conversion.
Does a clean conversion mean a good bet?
No. A conversion only changes how a price is written, never what it is worth. Judging value needs an estimate of the real chance, compared with the price on offer, a separate calculation built around an edge you already believe you have.
What does a price like -110 or 5/2 actually mean?
-110 American is a decimal of about 1.91: stake £110 to profit £100, or scaled down, £11 to profit about £10. 5/2 fractional is a decimal of 3.50: risk £2, profit £5, so a £20 stake returns £70 including the stake.