Odds Converter
Type a price in any format — decimal, fractional, or American — and get the other two back, plus the implied chance and what a stake would return. Below, a full reference table, plain-English definitions, and the actual working behind every conversion.
Key terms, plainly put
Odds get written three different ways depending on where you're betting. Here's what each one is really telling you.
Fractional
Common on a UK racecourse or in the Saturday papers. A fraction states profit against your stake — not the full payout. 2/1 means a £10 bet nets £20 profit, plus your original £10 back, so £30 lands in total. 5/2 means £2 staked makes £5 profit. The wider the gap between the two numbers, the longer the odds.
Decimal
The standard across Europe, Australia, and most exchanges. The number is your total return per unit staked, stake included. 3.00 means a £10 bet returns £30 in total if it lands (£20 profit). Quick to do rough maths with in your head, which is likely why Betfair and friends default to it.
American
Standard on US sportsbooks, and it flips depending on the sign. A plus number like +250 shows profit on a $100 stake — $100 wins $250. A minus number like -150 shows the stake needed to profit $100 — you'd need to risk $150. Minus for favourites, plus for underdogs.
Implied chance
Every price carries a probability, whether the bookmaker spells it out or not. 4.00 implies a 25% chance. Useful for sizing up a price against your own read of a match — if you rate the true chance higher, that price might be worth a second look. It won't tell you a bet is good on its own, and it doesn't strip out the bookmaker's margin.
The maths behind it
Everything converts through decimal first, since it's the easiest to work with, then out to whichever format you need.
Turning a price into a percentage
- From decimal: 100 ÷ decimal odds. 100 ÷ 2.00 = 50%.
- From fractional: 1 ÷ (the fraction as a decimal + 1), then ×100. 3/1 → 1 ÷ 4 × 100 = 25%.
- From American, plus: 100 ÷ (odds + 100) × 100. +150 → 100 ÷ 250 × 100 = 40%.
- From American, minus: drop the sign, odds ÷ (odds + 100) × 100. -300 → 300 ÷ 400 × 100 = 75%.
Going backwards — percentage into a price
- To decimal: 1 ÷ (percentage ÷ 100). 50% → 1 ÷ 0.5 = 2.00.
- To fractional: same, minus 1. 25% → (1 ÷ 0.25) − 1 = 3, or 3/1.
- To American: above 50%, negative — percentage ÷ (1 − percentage) × -100. 60% → -150. Below 50%, positive — (100 ÷ percentage) − 100. 10% → +900.
Format to format, directly
- Fractional → decimal: add 1. 3/1 → 4.00.
- Decimal → fractional: subtract 1. 4.00 → 3, or 3/1.
- American → decimal: plus odds, (odds ÷ 100) + 1. Minus odds, 1 − (100 ÷ odds). +300 = 4.00; -300 = 1.33.
- Decimal → American: at 2.00+, (decimal − 1) × 100. Below 2.00, -100 ÷ (decimal − 1). 3.00 = +200; 1.50 = -200.
Worked example
A correct-score price comes back at decimal 7.50. 100 ÷ 7.50 gives an implied chance of 13.33% — before the bookmaker's margin gets stripped out, which it never is on a live price. A £10 stake at that price returns £75.00 total, £65.00 of it profit. As a fraction, that's roughly 13/2; in American terms, +650.
The full conversion table
Handy for the moment your bookmaker's app flashes "13/2" and you want to know what that pays without reaching for the calculator above. Find your price in any column and read across — it runs from odds-on shorties like 1/10 out to rank outsiders at 1000/1.
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/100 | 1.01 | -10000 | 99% |
| 1/10 | 1.10 | -1000 | 90.9% |
| 1/5 | 1.20 | -500 | 83.3% |
| 2/9 | 1.22 | -455 | 82% |
| 1/4 | 1.25 | -400 | 80% |
| 2/7 | 1.29 | -345 | 77.5% |
| 3/10 | 1.30 | -333 | 76.9% |
| 1/3 | 1.33 | -303 | 75.2% |
| 4/11 | 1.36 | -278 | 73.5% |
| 2/5 | 1.40 | -250 | 71.4% |
| 4/9 | 1.44 | -227 | 69.4% |
| 1/2 | 1.50 | -200 | 66.7% |
| 8/15 | 1.53 | -189 | 65.4% |
| 4/7 | 1.57 | -175 | 63.7% |
| 8/13 | 1.62 | -161 | 61.7% |
| 4/6 | 1.67 | -149 | 59.9% |
| 8/11 | 1.73 | -137 | 57.8% |
| 4/5 | 1.80 | -125 | 55.6% |
| 5/6 | 1.83 | -120 | 54.6% |
| 10/11 | 1.91 | -110 | 52.4% |
| 1/1 (evens) | 2.00 | +100 | 50% |
| 21/20 | 2.05 | +105 | 48.8% |
| 11/10 | 2.10 | +110 | 47.6% |
| 23/20 | 2.15 | +115 | 46.5% |
| 6/5 | 2.20 | +120 | 45.5% |
| 5/4 | 2.25 | +125 | 44.4% |
| 11/8 | 2.38 | +138 | 42% |
| 7/5 | 2.40 | +140 | 41.7% |
| 6/4 | 2.50 | +150 | 40% |
| 8/5 | 2.60 | +160 | 38.5% |
| 13/8 | 2.62 | +162 | 38.2% |
| 7/4 | 2.75 | +175 | 36.4% |
| 9/5 | 2.80 | +180 | 35.7% |
| 15/8 | 2.88 | +188 | 34.7% |
| 2/1 | 3.00 | +200 | 33.3% |
| 11/5 | 3.20 | +220 | 31.3% |
| 9/4 | 3.25 | +225 | 30.8% |
| 12/5 | 3.40 | +240 | 29.4% |
| 5/2 | 3.50 | +250 | 28.6% |
| 13/5 | 3.60 | +260 | 27.8% |
| 11/4 | 3.75 | +275 | 26.7% |
| 3/1 | 4.00 | +300 | 25% |
| 16/5 | 4.20 | +320 | 23.8% |
| 10/3 | 4.33 | +333 | 23.1% |
| 7/2 | 4.50 | +350 | 22.2% |
| 4/1 | 5.00 | +400 | 20% |
| 9/2 | 5.50 | +450 | 18.2% |
| 5/1 | 6.00 | +500 | 16.7% |
| 11/2 | 6.50 | +550 | 15.4% |
| 6/1 | 7.00 | +600 | 14.3% |
| 13/2 | 7.50 | +650 | 13.3% |
| 7/1 | 8.00 | +700 | 12.5% |
| 15/2 | 8.50 | +750 | 11.8% |
| 8/1 | 9.00 | +800 | 11.1% |
| 9/1 | 10.00 | +900 | 10% |
| 10/1 | 11.00 | +1000 | 9.1% |
| 11/1 | 12.00 | +1100 | 8.3% |
| 12/1 | 13.00 | +1200 | 7.7% |
| 13/1 | 14.00 | +1300 | 7.1% |
| 14/1 | 15.00 | +1400 | 6.7% |
| 15/1 | 16.00 | +1500 | 6.3% |
| 16/1 | 17.00 | +1600 | 5.9% |
| 18/1 | 19.00 | +1800 | 5.3% |
| 20/1 | 21.00 | +2000 | 4.8% |
| 25/1 | 26.00 | +2500 | 3.8% |
| 33/1 | 34.00 | +3300 | 2.9% |
| 40/1 | 41.00 | +4000 | 2.4% |
| 50/1 | 51.00 | +5000 | 2% |
| 66/1 | 67.00 | +6600 | 1.5% |
| 100/1 | 101.00 | +10000 | 1% |
| 1000/1 | 1001.00 | +100000 | 0.1% |
Common questions
What's the real difference between fractional and decimal?
Fractional shows profit only — your stake sits outside the number. Decimal shows the whole return, stake included. Same price, two ways of writing it.
Why do American odds flip between plus and minus?
The sign marks favourite versus underdog. A plus figure (+200) is what a $100 stake profits. A minus figure (-200) is what you'd need to risk to profit $100. Favourites: minus. Underdogs: plus.
Does implied chance already account for the bookmaker's cut?
No — converting one price gives you the raw number. Bookmakers build a margin across the whole market, so the true, margin-free chance sits a touch lower than any single price implies.
Can this help me spot value?
It can help you compare a price against your own read of an outcome — a meaningfully higher estimate on your side is the basic idea behind a value bet. It won't generate that estimate for you; it only converts and calculates.
Is the format the same everywhere?
Decimal rules most of Europe and the exchanges. Fractional is still standard at UK and Irish high-street bookmakers. American is standard in the US. The underlying price never changes — only the notation does.