This odds converter turns a price written in decimal, fractional or American odds, or as an implied probability, into the other three formats as you type. For example, $2.50 (an illustrative price) is 3/2, +150 and a 40% implied probability. Australian bookmakers quote decimal odds, so every conversion runs through the decimal price, and how betting odds work covers the maths behind it.
How to use the odds converter
Pick the format you are typing in, then type the price. The four boxes fill in together, so you never convert twice. Switching the format empties the box, because the same digits are a different price in each one.
A half-typed price such as "1." or "5/" leaves the four boxes blank, and the note under the input only turns red once you leave the box.
The converter reads prices from $1.01 to $10,001 in every format (1/100 to 10000/1, -10000 to +1000000, or about 0.01% to 99%) and refuses anything outside that band. A price at or under $1.00 returns no more than the stake, and decimal prices go up in cents, so $1.01 is the shortest one it reads. No American price sits between -100 and +100: even money is written -100 or +100. A percentage is read as a percentage, so 40 and 40% are the same price, and 0.8 means 0.8%, which is 1 / 0.008 = 125, a $125 shot.
Each box rounds on its own: decimal to the cent, American to a whole number, the percentage to one place (two under 1%), and the fraction to a simple one close to the price.
Decimal, fractional and American odds compared
With an illustrative price of $1.91:
| Format | What the number counts | $1.91 looks like |
|---|---|---|
| Decimal | Total return per $1 staked, stake included | 1.91 |
| Fractional | Profit per unit staked | 91/100 |
| American | Profit on $100, or the stake needed to win $100 | -110 |
| Implied probability | The chance the price implies | 52.4% |
Working for $1.91: fraction = 1.91 - 1 = 0.91 = 91/100; American = -100 / 0.91 = -109.89, shown as -110; implied probability = 1 / 1.91 = 0.5236, shown as 52.4%.
Decimal odds are easiest to read because the stake is already in them: stake x price is the total coming back. Fractional odds leave the stake out, so 3/2 pays $3 profit for every $2 staked, a $5 return, which is decimal $2.50. American odds flip their meaning at even money, which is why they carry a sign. Tote dividends and starting prices are decimal numbers too, and odds types explained covers where each kind of price comes from.
How to convert decimal, fractional and American odds
Every conversion goes through decimal odds, so there are few lines to remember.
- implied probability = 1 / decimal odds
- decimal odds = 1 / implied probability
- decimal odds from a fraction = numerator / denominator + 1
- decimal odds from positive American odds = American / 100 + 1
- decimal odds from negative American odds = 100 / absolute American + 1
- fractional odds = decimal odds - 1, in lowest terms: 2.50 - 1 = 1.50 = 150/100 = 3/2
- American odds at $2.00 or longer = (decimal odds - 1) x 100
- American odds under $2.00 = -100 / (decimal odds - 1)
Every price under $2.00 is a minus number in American odds, because you stake more than $100 to win $100.
Example: an illustrative $2.50. The profit per dollar is 2.50 - 1 = 1.50, which is 3/2. It is $2.00 or longer, so the American form is positive, (2.50 - 1) x 100 = +150, and the implied probability is 1 / 2.50 = 40%. Under $2.00 the sign flips: $1.33 is -100 / (1.33 - 1) = -303 after rounding.
Why $1.91 shows as 91/100, not 10/11
A two-decimal price converts exactly: $1.91 is 0.91 profit per dollar, which is 91/100. Traditional fractions such as 10/11 and 10/3 are $1.909 and $4.333, which round to $1.91 and $4.33. Type the fraction in the Fractional box and the converter keeps it, in lowest terms, so 4/6 comes back as 2/3. With illustrative prices:
| You type | Decimal | Fractional | American | Implied probability |
|---|---|---|---|---|
| 1.91 | 1.91 | 91/100 | -110 | 52.4% |
| 10/11 | 1.91 | 10/11 | -110 | 52.4% |
| 1.33 | 1.33 | 33/100 | -303 | 75.2% |
| 1/3 | 1.33 | 1/3 | -300 | 75.0% |
| 4.33 | 4.33 | 333/100 | +333 | 23.1% |
| 10/3 | 4.33 | 10/3 | +333 | 23.1% |
The American form rounds to a whole number, so $1.33 is -303 while 1/3 is -300. A price typed to three places can round differently in each box too: 1.995 shows $2.00 and 1/1 beside -101 and 50.1%.
Turning odds into a probability
Reading a price as an implied probability is what lets you compare it with anything else. If you think a runner wins one time in three, you need better than $3.00: $2.80 is not enough.
That comparison is also how a margin becomes visible. Add the percentages across one bookmaker's market and the total comes to more than 100%; the bookmaker margin calculator measures that margin from the prices. Taking it out gives an estimate of the fair price, which fair odds works through, and comparing offers with that estimate is positive expected value betting. Shop elsewhere and the numbers move, which is what an odds comparison board shows.
Risk: Betting involves risk. A conversion shows what a price implies, not what will happen: $2.80 implies 35.7%, and whether it is worth taking depends on the real chance. The fair price is an estimate, so a bet priced above it can still lose, and often does. See responsible gambling for limits and support.
Misreadings that cost money
With illustrative prices:
| Mistake | What it costs | The fix |
|---|---|---|
| Reading 5/2 as $2.50 | $10 returns $35 at 5/2, not $25 | Add 1 to the fraction: 5/2 + 1 = $3.50 |
| Dropping the minus sign | -150 is $1.67, so $10 returns $16.67, not the $25 that +150 pays | Check the sign before you convert |
| Typing 0.4 for 40% | The converter reads 0.4 as 0.4%, a $250 price | Type 40 or 40% |
Why a bonus bet at the same odds pays less
A bonus bet is quoted in the same odds but pays differently. On most Australian bonus bets the stake is not returned, so a winner pays the winnings only, bonus x (price - 1). A cash bet returns stake x price, because the stake comes back too. With illustrative numbers, a $20 bonus bet at $3.40 pays 20 x (3.40 - 1) = $48, where a $20 cash bet returns 20 x 3.40 = $68: the same $48 profit, plus the $20 stake back. Each bookmaker's terms decide how its bonus bets work, so check them.
The bonus bet converter does that arithmetic, including the lay stake if you hedge it.
Risk: Betting involves risk. A bonus bet that loses pays nothing, a lay has to be matched before a hedge is in place, and a bookmaker can limit your stakes, void bets or close your account under its terms.