Decimal and fractional odds: three ways to show one price
American, decimal and fractional odds are three ways to write the same price. Decimal odds show the total return per $1, including your stake.
Reviewed Oct 14, 2026
Answer first
90s| American | Decimal | Fractional | Implied chance |
|---|---|---|---|
| −200 | 1.50 | 1/2 | 66.7% |
| −110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 (evens) | 50.0% |
| +150 | 2.50 | 6/4 | 40.0% |
| +300 | 4.00 | 3/1 | 25.0% |
| +900 | 10.00 | 9/1 | 10.0% |
Key numbers
One price, three formats
In short
Key takeaways
- Decimal odds include your stake: 2.50 returns $2.50 for each $1 bet.
- Implied chance is 1 divided by the decimal price.
- Fractional odds show profit over stake, so 6/4 wins $6 for every $4.
- Add the implied chances of both sides; anything over 100% is the book’s margin.
Sequence
Converting between formats
Step 01
Decimal to American (2.00 or more)
Subtract 1 and multiply by 100: 2.50 becomes +150.
Step 02
Decimal to American (under 2.00)
Divide −100 by (decimal − 1): 1.50 becomes −200.
Step 03
Fractional to decimal
Divide and add 1: 6/4 is 1.5 + 1 = 2.50.
Step 04
Any format to chance
Turn it into decimal, then divide 1 by it.
Finding the margin on a −110 / −110 game
| Side | Decimal | Implied chance |
|---|---|---|
| Team A | 1.91 | 52.4% |
| Team B | 1.91 | 52.4% |
| Total | — | 104.8% |
The extra 4.8% over 100% is the book’s margin, often called the vig or overround.
Why US books use American odds
American odds started with US racing and bookmaking. Most US sportsbook apps let you switch the display to decimal in settings.
Decimal odds make parlays easy. Multiply the legs: 1.91 × 1.91 is about 3.65, so a $10 two-leg parlay returns about $36.50.
Floor rules
Odds terms
Know before you sit
- Evens
- A price of 2.00 or +100: win the same as you stake.
- Odds-on
- A price below 2.00: you risk more than you win.
- Overround
- The total implied chance over 100% on one market.
- Return
- Stake plus profit.
Using decimal odds to compare books
Decimal prices make shopping easy. If one book offers 2.05 and another 1.95 on the same side, a $100 bet returns $205 at the first and $195 at the second.
Over 100 bets, that small gap adds up to $1,000 in returns. Comparing prices is one of the few things a bettor fully controls.
Fractional odds are common in UK and Irish racing. You may see them on simulcast screens in US race books for overseas races.
Common fractional prices
| Fractional | Decimal | American |
|---|---|---|
| 1/4 | 1.25 | −400 |
| 4/5 | 1.80 | −125 |
| 11/10 | 2.10 | +110 |
| 5/2 | 3.50 | +250 |
| 7/1 | 8.00 | +700 |
| 20/1 | 21.00 | +2000 |
Common mistakes
- Forgetting the stake is included
- Decimal odds already include your stake. A price of 2.50 returns $25 on $10, which is $15 profit, not $25.
- Reading fractional odds as decimal
- 6/4 is not 6.4. It means a profit of 6 for every 4 staked, which is 2.50 in decimal.
- Ignoring the margin
- Adding both sides shows the book’s cut. Two books can show the same favorite with different margins.
- Rounding too early
- Rounding 1.909 to 1.9 in parlay math adds up across legs. Use the full price when you calculate.
- Treating implied chance as true chance
- Implied chance includes the margin. The true chance of each side is a little lower than the price suggests.
A worked example in all three formats
Say a team is priced at +150. In decimal that is 2.50, and in fractional 6/4. A $20 bet returns $50 in total in every format: $30 profit and the $20 stake.
The other side might be −180, or 1.56 in decimal. Its implied chance is 64.3%. Add the 40.0% from the first side and the market totals 104.3%, so the margin is about 4.3%.
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01Reading odds
What does 2.50 mean in odds?
A $1 bet returns $2.50 in total if it wins: $1.50 profit plus your $1 stake. That equals +150 in American odds.
What does 6/4 mean?
You win $6 for every $4 staked, plus your stake back. In decimal it is 2.50, and in American odds +150.
How do I turn odds into a percentage?
Convert the price to decimal, then divide 1 by it. A price of 4.00 means 25%, and 1.50 means 66.7%.
Which odds format is best?
None changes the price. Decimal is easiest for math; American is standard in US apps.
02Sportsbook settings
Can I change odds format in US sportsbook apps?
Many licensed apps offer decimal or fractional display in account settings. The payout stays the same.
Why don’t both sides add up to 100%?
The book builds in a margin. On a −110 / −110 game the two implied chances add up to about 104.8%.
03More odds questions
What does a decimal price of 1.25 mean?
A $1 bet returns $1.25 in total, a $0.25 profit. It is a strong favorite, about 80% implied, or −400 in American odds.
How do I calculate a parlay in decimal?
Multiply the decimal prices of each leg. Three legs at 1.91 make about 6.97, so $10 returns about $69.70.
Are fractional odds used in the US?
Rarely in sportsbooks, but horse racing odds on the tote board are shown in a similar form, such as 5-2.
Sources
- American Gaming Association — Sports betting Not from a registry (Reference source, not an official registry) · accessed Oct 14, 2026US sports betting markets
- Nevada Gaming Control Board · accessed Oct 14, 2026Approved games and gaming revenue reports
- National Council on Problem Gambling — Help and resources Not from a registry (Reference source, not an official registry) · accessed Oct 14, 2026Free, confidential help: call or text 1-800-GAMBLER
- American Gaming Association — Research Not from a registry (Reference source, not an official registry) · accessed Oct 14, 2026US casino industry data