How to Read Fractional Odds
The number on the left is the profit. The number on the right is the stake required.
Profit / Stake
At odds of 5/2 (spoken as "five to two"), a winning 2 pound stake produces 5 pounds profit. The 2 pound stake is also returned, making the total return 7 pounds. DraftKings' glossary provides an operator example of fractional odds as a profit-to-stake expression (DraftKings betting terminology).
Here are worked fractional-odds conversions. They are arithmetic examples, not evidence that a price is commonly available:
- Evens (1/1): Profit equals the stake. Stake 10 pounds, profit 10 pounds, total return 20 pounds.
- 2/1: Profit is double the stake. Stake 10 pounds, profit 20 pounds, total return 30 pounds.
- 5/2: Stake 2, profit 5. Stake 10 pounds, profit 25 pounds, total return 35 pounds.
- 11/8: Stake 8, profit 11. Stake 10 pounds, profit 13.75 pounds, total return 23.75 pounds.
- 1/2: Stake 2, profit 1. Stake 10 pounds, profit 5 pounds, total return 15 pounds.
Calculating Returns
The formulas for fractional odds are:
Profit = Stake x (Numerator / Denominator)
Total Return = Stake + Profit
Suppose an illustrative selection is priced at 7/4 and the stake is 20 pounds:
- Profit: 20 x (7 / 4) = 35 pounds
- Total return: 20 + 35 = 55 pounds
For odds like 11/10, a 10 pound stake returns:
- Profit: 10 x (11 / 10) = 11 pounds
- Total return: 10 + 11 = 21 pounds
Odds-On and Odds-Against
When the first number is larger than the second, the odds are "against" you, meaning the potential profit exceeds the stake. Examples include 2/1, 5/2, and 7/4.
When the second number is larger, the odds are "on", meaning the potential profit is less than the stake. Examples include 1/2, 4/9, and 2/5. An odds-on fraction does not prove the selection is likely to win.
Evens (1/1) is the dividing line, where profit equals stake exactly.
For example, a winning 10 pound stake at 2/5 produces 4 pounds profit and a 14 pound total return. The corresponding raw break-even probability is 71.4%, but that is a price conversion rather than an independently estimated chance.
Converting Fractional to Decimal Odds
To convert fractional odds to decimal:
Decimal Odds = (Numerator / Denominator) + 1
| Fractional | Calculation | Decimal |
|---|---|---|
| 1/2 | (1/2) + 1 | 1.50 |
| Evens | (1/1) + 1 | 2.00 |
| 6/4 | (6/4) + 1 | 2.50 |
| 2/1 | (2/1) + 1 | 3.00 |
| 5/2 | (5/2) + 1 | 3.50 |
| 11/8 | (11/8) + 1 | 2.375 |
To convert the other way, subtract 1 from the decimal odds and express the result as a fraction. Decimal 2.50 becomes 1.50, which is 3/2 (or equivalently, 6/4).
Converting Fractional Odds to Probability
Implied Probability = Denominator / (Numerator + Denominator) x 100
At 2/1, the implied probability is 1 / (2 + 1) x 100 = 33.3%. At 1/2, it is 2 / (1 + 2) x 100 = 66.7%.
This is the price's raw break-even probability. It is not automatically the event's true probability because a quoted market can contain margin. A value assessment needs an independent probability estimate and the relevant settlement rules (OpenStax probability terminology).
Fractional and Decimal Odds Carry the Same Price
Changing display format does not change the economics of a quoted price. Fractional 5/2 and decimal 3.50 represent the same possible profit and return:
| Format | Winning profit on 10 | Total return |
|---|---|---|
| Fractional 5/2 | 25 | 35 |
| Decimal 3.50 | 25 | 35 |
An operator may support one or several display formats. Check the interface rather than assuming a format is available, and record prices in one consistent format when comparing markets.
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Related resources
Continue with Decimal Odds: What They Mean in Betting for the next part of this topic, or return to Betting Glossary: Every Betting Term Explained in Plain English to compare the other guides in this collection.
Continue learning
- Next guide: Free Bet Meaning
- Related guide: Half-Time/Full-Time
- Go deeper: How to Read and Calculate Fractional Odds
Assumptions and limitations
Fractional odds express potential profit relative to stake; the returned stake is added separately. Examples assume ordinary cash settlement and exclude deductions, commission, dead heats, and promotional adjustments. DraftKings' glossary is one current operator reference, while converted displays can differ slightly because of rounding.
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