Betting odds tell you two things: how much you win if your bet comes in, and how likely the bookmaker thinks the outcome is. There are three main formats, decimal (2.50), fractional (6/4) and American (+150), and they all describe the same price in different ways. Once you understand how to read and convert them, you can compare bookmakers anywhere in the world.
Betting odds explained: the three formats
| Format | Example | Where it is common | What it shows |
|---|---|---|---|
| Decimal | 2.50 | South Africa, Nigeria, Kenya, Ghana, most of Europe | Total return per 1 unit staked, including stake |
| Fractional | 6/4 | UK and Ireland, especially horse racing | Profit relative to stake |
| American (moneyline) | +150 / -200 | United States | Profit on 100, or stake needed to win 100 |
Most bookmakers let you switch format in the settings, so you can use whichever you find easiest. Our odds converter switches between them instantly.
Decimal odds
Decimal odds are the simplest. Multiply your stake by the odds to get your total return, which includes your original stake.
Return = stake × decimal odds
Profit = stake × (decimal odds − 1)
Example: a R100 bet at 2.50 returns R250 if it wins, which is R150 profit plus your R100 stake back. A ₦1,000 bet at 1.40 returns ₦1,400, or ₦400 profit.
Decimal odds below 2.00 mean the outcome is considered more likely than not (a favourite). Odds above 2.00 mean less likely than not (an underdog). Odds of exactly 2.00 are "evens".
Decimal odds dominate across Africa and continental Europe, and they are what you will see on bookmakers such as Betway, SportyBet and Bet9ja.
Fractional odds
Fractional odds show profit relative to stake. Odds of 6/4 ("six to four") mean you win £6 for every £4 staked, plus your stake back.
Profit = stake × (numerator ÷ denominator)
Example: £10 at 6/4 gives £10 × 1.5 = £15 profit, so £25 returned in total. At 1/2 ("two to one on"), £10 wins £5 profit, returning £15.
Fractional odds are traditional in the UK and Ireland and are still widely used in horse racing, although most UK bookmakers also offer decimal.
American odds
American odds, also called moneyline odds, use a plus or minus sign:
- Positive odds (+150) show the profit on a $100 stake. A $100 bet at +150 wins $150 profit, returning $250.
- Negative odds (−200) show how much you must stake to win $100 profit. You need to bet $200 at −200 to win $100, returning $300.
Favourites carry a minus sign and underdogs a plus sign. American odds are standard at US sportsbooks such as DraftKings and FanDuel. A very common price on spreads and totals is −110, which means risking $110 to win $100.
How to convert between odds formats
These formulas let you move between formats. The examples below all describe the same price.
Fractional to decimal
Decimal = (numerator ÷ denominator) + 1
6/4 → 1.5 + 1 = 2.50. 1/2 → 0.5 + 1 = 1.50. 5/1 → 6.00.
Decimal to fractional
Fractional = (decimal − 1) as a fraction, then simplify.
2.50 → 1.50 → 3/2 (also written 6/4). 1.80 → 0.80 → 4/5.
American to decimal
- Positive: Decimal = (American ÷ 100) + 1. So +150 → 1.50 + 1 = 2.50.
- Negative: Decimal = (100 ÷ |American|) + 1. So −200 → 0.50 + 1 = 1.50. And −110 → 0.909 + 1 = 1.91.
Decimal to American
- If decimal is 2.00 or higher: American = (decimal − 1) × 100. So 2.50 → +150.
- If decimal is below 2.00: American = −100 ÷ (decimal − 1). So 1.50 → −100 ÷ 0.50 = −200.
Quick reference
| Decimal | Fractional | American | Implied probability |
|---|---|---|---|
| 1.25 | 1/4 | −400 | 80.0% |
| 1.50 | 1/2 | −200 | 66.7% |
| 1.91 | 10/11 | −110 | 52.4% |
| 2.00 | 1/1 (evens) | +100 | 50.0% |
| 2.50 | 6/4 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 5.00 | 4/1 | +400 | 20.0% |
| 11.00 | 10/1 | +1000 | 9.1% |
Implied probability: what the odds really say
Every price can be turned into an implied probability, the chance of the outcome that the odds suggest.
Implied probability = 1 ÷ decimal odds
At 2.50, implied probability is 1 ÷ 2.50 = 0.40, or 40%. At 1.25, it is 80%.
For fractional odds, use denominator ÷ (numerator + denominator). For 6/4 that is 4 ÷ 10 = 40%.
For American odds:
- Positive: 100 ÷ (American + 100). So +150 → 100 ÷ 250 = 40%.
- Negative: |American| ÷ (|American| + 100). So −200 → 200 ÷ 300 = 66.7%.
Why the probabilities add up to more than 100%
If you add up the implied probabilities for every outcome in a market, the total is usually more than 100%. In a football match priced Home 2.10, Draw 3.40, Away 3.60, the implied probabilities are about 47.6%, 29.4% and 27.8%, totalling roughly 104.8%. The extra 4.8% is the bookmaker's built-in margin. Our guide to bookmaker margin explains this in detail, and the margin calculator works it out for any market.
Why understanding odds matters
Reading odds properly helps you in three practical ways:
- You can compare prices fairly. A US sportsbook showing −120 and a European one showing 1.83 are offering almost the same price. Converting them makes comparison simple.
- You can judge value. If you think an outcome has a 50% chance and the odds are 2.20 (45.5% implied), the price is better than your estimate suggests it should be. See how to find value bets.
- You can spot poor prices. Small differences add up. Over 100 bets, consistently taking 1.90 instead of 2.00 makes a real difference to your results. Our odds comparison pages show who is offering the best price on each market.
Remember that odds are an estimate, not a promise. A 1.25 favourite still loses roughly one time in five, and nothing about a price guarantees an outcome. Bet only what you can afford to lose, and visit our responsible gambling page if you need support. Betting is for over-18s only (21+ in most US states and 25 in Uganda).
FAQ
Which odds format is best?
None is better in terms of value; they all express the same price. Decimal odds are usually easiest because you simply multiply stake by odds to get your return. Choose the format you find clearest and switch it in your bookmaker's settings.
What do odds of 1.50 mean?
Decimal odds of 1.50 mean you get 1.50 back for every 1 staked. A R100 bet returns R150, which is R50 profit plus your stake. The implied probability is about 66.7%, equivalent to 1/2 fractional or −200 American.
What does +200 mean in betting?
In American odds, +200 means a $100 bet wins $200 profit, returning $300 in total. It is the same as decimal 3.00 and fractional 2/1, with an implied probability of 33.3%.
How do I convert odds to probability?
Divide 1 by the decimal odds. Odds of 4.00 give 1 ÷ 4 = 25%. Convert fractional or American odds to decimal first if that is easier, or use our free odds converter.
Are higher odds better?
Higher odds pay more if you win, but they also mean the outcome is less likely. What matters is whether the odds are higher than the true chance justifies, and whether you are getting the best price available across bookmakers.