Think of odds formats as currencies. A price of 2.75, 7/4 and +175 is the same value written three ways, much like the same amount shown in pounds, euros and dollars. The skill is knowing the exchange rate, and the good news is that it only takes a few lines of maths.
This guide shows you how to convert between decimal, fractional and American odds, with worked examples and a reference table you can come back to. It is written to help you read the numbers, nothing more.
Key Takeaways
- Decimal, fractional and American odds all describe the same price in different notation.
- Decimal is the easiest hub format: convert to decimal first and everything else gets simpler.
- Decimal odds include the original stake, while fractional and American odds describe profit.
- Positive American odds mark an underdog and negative American odds mark a favourite.
- Converted numbers can differ slightly from listed prices because fractions are often rounded.
Why Odds Formats Differ
Different regions grew up with different habits. Fractional odds are the traditional UK and Irish style, decimal odds dominate continental Europe, Australia and much of Asia, and American odds (also called moneyline) are standard in the United States.
Since football is a global game, you will meet all three. A Premier League price may appear as 11/10 on a UK site, 2.10 on a European one and +110 in a US app, and all three mean the same thing.
The Core Idea: Convert Through Decimal
Decimal odds show the total return for every 1 unit, including the original unit. That single detail makes decimal the cleanest starting point, because the profit is simply the decimal number minus 1.
Once you have the decimal figure, you can reach any other format in one step. You can also turn it into a probability by dividing 1 by it, which is the idea behind the rest of this series.
How to Convert Between Formats
Each conversion below uses the same logic. Keep the profit-versus-total-return difference in mind and the formulas stop feeling arbitrary.
1. Decimal to Fractional
Subtract 1 from the decimal number, then write the result as a fraction. A decimal of 2.75 gives 1.75, which is 175/100 and simplifies to 7/4.
Bookmaker-style fractions are usually kept tidy, so a price like 3.33 tends to be listed as 7/3 rather than 233/100.
2. Fractional to Decimal
Divide the top number by the bottom number and add 1. So 7/4 becomes 1.75 + 1 = 2.75, and 2/5 becomes 0.4 + 1 = 1.40.
3. Decimal to American
The formula depends on which side of 2.00 you are on:
- Decimal of 2.00 or higher: American = (decimal – 1) × 100. For 2.75, that is 1.75 × 100 = +175.
- Decimal below 2.00: American = -100 ÷ (decimal – 1). For 1.40, that is -100 ÷ 0.40 = -250.
Exactly 2.00 is +100, which is the same as evens.
4. American to Decimal
Again there are two cases:
- Positive American odds: decimal = (American ÷ 100) + 1. For +175, that is 1.75 + 1 = 2.75.
- Negative American odds: decimal = (100 ÷ American, ignoring the minus sign) + 1. For -250, that is 0.40 + 1 = 1.40.
5. Fractional to American, and Back
You can go through decimal, or use a direct shortcut. If the fraction is 1/1 or bigger, multiply it by 100 and add a plus sign: 7/4 = 1.75 × 100 = +175. If the fraction is smaller than 1/1, divide 100 by the fraction and add a minus sign: 2/5 = 100 ÷ 0.4 = -250.
Going back is just as direct. A positive American number divided by 100 gives the fraction, so +175 is 175/100 or 7/4. A negative one flips it: -250 means 100/250, which is 2/5.
Worked Examples
Let’s run three prices through every format. These are illustrative numbers rather than real market prices.
| Description | Decimal | Fractional | American |
|---|---|---|---|
| Strong Favourite | 1.40 | 2/5 | -250 |
| Slight Underdog | 2.10 | 11/10 | +110 |
| Clear Underdog | 2.75 | 7/4 | +175 |
The pattern is easy to spot. The shorter the decimal price, the more negative the American number and the smaller the fraction. The longer the decimal price, the bigger all three become.
Converting a Full Market
Let’s put the formulas to work on a full match result market. A UK-style site lists the prices as fractions, and the table below shows the same market in the other two formats, along with the implied probability of each outcome.
| Outcome | Fractional | Decimal | American | Implied Probability |
|---|---|---|---|---|
| Home Win | 11/10 | 2.10 | +110 | 47.6% |
| Draw | 12/5 | 3.40 | +240 | 29.4% |
| Away Win | 5/2 | 3.50 | +250 | 28.6% |
The probabilities add up to 105.6%, not 100%. That extra is the margin built into the market, and it is identical whichever format the prices are written in. Converting formats changes the notation, never the underlying numbers.
A Note on Hong Kong, Indonesian and Malay Odds
Asian markets often use three more formats. Hong Kong odds are decimal odds minus 1, so they show profit only. To go back to decimal, add 1.
Indonesian and Malay odds use the same 1-unit idea but flip between positive and negative around evens, in opposite directions. Here is how two of the earlier prices look:
| Decimal | Hong Kong | Indonesian | Malay |
|---|---|---|---|
| 1.40 | 0.40 | -2.50 | +0.40 |
| 2.75 | 1.75 | +1.75 | -0.57 |
Most readers can skip these. If you do meet them, convert to decimal first and the rest of this guide applies.
Quick Reference Table
Keep this handy if you read football odds in more than one format.
| Decimal | Fractional | American | Implied Probability |
|---|---|---|---|
| 1.25 | 1/4 | -400 | 80.0% |
| 1.50 | 1/2 | -200 | 66.7% |
| 1.80 | 4/5 | -125 | 55.6% |
| 2.00 | 1/1 | +100 | 50.0% |
| 2.25 | 5/4 | +125 | 44.4% |
| 2.50 | 3/2 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 4.00 | 3/1 | +300 | 25.0% |
| 5.00 | 4/1 | +400 | 20.0% |
| 8.00 | 7/1 | +700 | 12.5% |
| 11.00 | 10/1 | +1000 | 9.1% |
Mental Shortcuts That Save Time
You do not need a calculator for every price. A few quick rules do most of the work:
- Decimal of 2.00 is the midpoint. Below it is a favourite, above it is an underdog.
- A fraction with a bigger top number is an underdog. 5/2 is an underdog, while 2/5 is a favourite.
- Negative American numbers are favourites. The closer to -100, the closer the match is to a coin flip.
- Add 1 to move from profit to total return. That is the whole difference between fractional and decimal.
Why Converted Numbers Sometimes Don’t Match
Occasionally you will convert a price and land on a number that is close to, but not exactly, the one you see listed. Fractional prices are usually picked from a standard ladder, such as 4/9, 1/2 and 8/13, so a decimal of 1.44 might be shown as 4/9 (1.444).
The same rounding happens with American numbers. 4/9 converts to -225, while a decimal of 1.44 converts to roughly -227. The gap is rounding, not a different price, so treat small differences as noise.
Reading Converted Odds Alongside Predictions
Once everything sits in the same format, comparing prices to other forecasts becomes easy. The AI football predictions hub shows percentages for each result, which you can match against the implied probabilities from your converted odds.
If you follow Italy or Germany, the Serie A and Bundesliga prediction pages are good places to practise. The Serie A profile and Bundesliga profile add context on how each competition works.
Read More: How to Use AI Football Predictions shows how to read a prediction card once the percentages are in front of you.
When Conversion Actually Helps
Conversion earns its keep whenever your sources disagree on format. A UK article may quote fractions, a European statistics page may use decimals and a US-based tool may show moneyline numbers, all for the same fixture.
It also helps when you work in a spreadsheet. Decimal odds are the easiest to calculate with, so converting everything to decimal first lets you compare prices, work out probabilities and spot errors quickly. Once the habit sticks, the format on the screen stops mattering.
Common Conversion Slips
Most mistakes come from the same few places. Watch for these:
- Forgetting the stake in decimal odds. A decimal of 3.00 is 2/1, not 3/1.
- Mixing up the two American formulas. Positive and negative numbers use different maths.
- Dropping the minus sign. -200 is a favourite, while +200 is an underdog with a very different probability.
- Treating rounded fractions as exact. Small gaps between formats are normal.
- Converting without checking. Run the answer back through the reverse formula to confirm it lands on the starting price.
Conclusion
Decimal, fractional and American odds are three ways of writing the same idea, and conversion is a matter of knowing whether a number includes the original stake. Use decimal as your hub, remember the two American cases and keep the reference table nearby.
Once the formats stop getting in the way, you can focus on what the numbers actually say about a match. From here, the natural next step is turning any price into an implied probability.
This article is for educational purposes only and does not encourage gambling. Readers must be 18 or over, and anyone who feels gambling is affecting their life should contact a local support service.