15/8 Fractional Odds Explained
- Decimal
- 2.88
- American
- +188
- Fractional
- 15/8
- Implied probability
- 34.78%
- Polymarket
- 35¢
- $100 wins
- 187.50
- American
- +188
- Fractional
- 15/8
- Implied probability
- 34.78%
- Polymarket
- 35¢
- Profit
- 187.50
- Total return
- 287.50
2.875 decimal, +188 American, 34.78% implied probability
At 15/8 a 100 stake returns 287.50: the 100 back plus 187.50 profit. Decimal bettors know the price as 2.88, American bettors as +188, and prediction-market traders as a 35¢ share.
What 15/8 pays
Profit is stake multiplied by the fraction; add the stake back for the total return. A 100 stake wins 187.50 and returns 287.50.
| Stake | Profit | Total return |
|---|---|---|
| 10 | 18.75 | 28.75 |
| 25 | 46.88 | 71.88 |
| 50 | 93.75 | 143.75 |
| 100 | 187.50 | 287.50 |
| 500 | 937.50 | 1,437.50 |
| 1,000 | 1,875.00 | 2,875.00 |
Break-even and long-run results
The implied probability of 15/8 is bottom divided by top-plus-bottom, which is 34.78%. Win more often than that and you profit over time.
| Win rate | Return on stake |
|---|---|
| 35% | 0.6% |
| 50% | 43.8% |
| 55% | 58.1% |
| 60% | 72.5% |
| 65% | 86.9% |
15/8 is an odds-against price with an implied chance of 34.78%. Each winner pays 187.50 per 100. The fractional ladder steps up in quarters and halves here (9/4, 5/2, 11/4, 3/1), so small changes in the bookmaker's opinion show up as a move of one rung.
Converting 15/8 by hand
Divide the top of the fraction by the bottom and add one for the decimal price, 2.88. For the implied probability, divide the bottom by the sum of top and bottom: 34.78%. American odds follow from the decimal price: odds-against, so (2.88 − 1) × 100 gives +188. The same chance on a prediction market is a 35¢ share.
The vig at 15/8
With both sides of a two-way market at 15/8, implied probabilities would sum to -30.43% above 100%: a -43.75% margin on stakes. The fair price would be 2.00 decimal each side. Try other markets in the devig calculator.
15/8 on a betting exchange
On an exchange 15/8 is worth 2.838 decimal after 2% commission and 2.781 after 5%. Compare with the bookmaker before choosing where to bet.
| Commission | Effective decimal | Effective American | Break-even |
|---|---|---|---|
| 2% | 2.838 | +184 | 35.24% |
| 5% | 2.781 | +178 | 35.96% |
Neighbouring rungs on the ladder
Fractional prices move in fixed rungs rather than smooth steps, so a bookmaker who wants to shorten 15/8 slightly has to jump to the next rung down, and the size of that jump depends on where you are on the ladder. The nearby prices listed below are the rungs on either side of 15/8; each link opens the same set of facts for that price, which is the quickest way to see how much a one-rung move changes the implied probability and the payout.
Same price in other formats
Same price in other formats
Nearby prices
Nearby prices
Frequently asked questions
What does 15/8 mean in betting?
Fractional odds of 15/8 pay the top number in profit for every bottom number staked. A 100 stake wins 187.50 and returns 287.50. The implied probability is 34.78%.
What is 15/8 in decimal odds?
15/8 is 2.88 in decimal odds: divide the top by the bottom and add 1.
What is 15/8 in American odds?
15/8 converts to +188 in American odds.
Is 15/8 a good price?
A price is good only relative to the true chance. 15/8 implies 34.78%; if you believe the outcome is more likely than that, the price has value. Compare it with a devigged market to check.
Why do bookmakers use a ladder of fractions?
Tradition and readability: prices such as 6/4, 100/30 and 11/10 are quoted instead of their reduced forms because they are what racecourse bookmakers have always used. Decimal odds show the same prices with finer steps.