Learn a quick method to convert American odds to decimal and fractional formats with examples you can verify in seconds.
You are comparing lines on an NFL game. DraftKings shows Chiefs at -150 (American), but a European book lists them at 1.667 (decimal). Are these the same price? You need to convert one format to the other to find out.
Here is how to do it in your head — and when to skip the math entirely.
For plus odds like +150, +200, or +110:
Formula: Decimal = (American / 100) + 1
Example: +150
A $100 bet at +150 American returns $250 total ($150 profit + $100 stake). Decimal 2.50 tells you the same thing: multiply your stake by 2.50 to get your total return.
| American | Calculation | Decimal |
|---|---|---|
| +110 | (110/100) + 1 | 2.10 |
| +150 | (150/100) + 1 | 2.50 |
| +200 | (200/100) + 1 | 3.00 |
| +300 | (300/100) + 1 | 4.00 |
For minus odds like -110, -150, or -200:
Formula: Decimal = (100 / |American|) + 1
Example: -150
So the Chiefs at -150 American and 1.667 decimal are the same price. Mystery solved.
| American | Calculation | Decimal |
|---|---|---|
| -110 | (100/110) + 1 | 1.909 |
| -150 | (100/150) + 1 | 1.667 |
| -200 | (100/200) + 1 | 1.500 |
| -300 | (100/300) + 1 | 1.333 |
Tip: The mental shortcut for -110 is "about 1.91." You will see -110 so often (it is the standard spread/total price) that memorizing this one conversion saves time on almost every bet.
Once you have decimal odds, fractional is one step away:
Formula: Fractional = (Decimal - 1), expressed as a fraction
Example: 2.50 decimal
This means for every $2 you risk, you profit $3. Fractional odds are common in UK betting markets.
| Decimal | Minus 1 | Fractional |
|---|---|---|
| 1.50 | 0.50 | 1/2 |
| 1.909 | 0.909 | 10/11 |
| 2.00 | 1.00 | 1/1 (evens) |
| 2.50 | 1.50 | 3/2 |
| 3.00 | 2.00 | 2/1 |
Decimal odds make two things easier:
Parlay math. To calculate combined parlay odds, you multiply each leg's decimal odds together. With American odds, you would need to convert first. Example: a 3-leg parlay at 1.909 × 2.50 × 1.667 = 7.96 combined decimal odds.
Quick payout calculation. Multiply your stake by the decimal odds to get your total return. A $50 bet at 2.50 = $125 back ($75 profit). No separate formula needed for favorites vs. underdogs.
Tip: You do not need to memorize any of this. The Odds Converter converts between American, decimal, fractional, and implied probability in real time. Type in one format and all others update instantly.
Enter -150 into the Odds Converter and verify it shows 1.667 decimal, 2/3 fractional, and 60.00% implied probability. Then try your own lines from tonight's games.
Divide by 100 and add 1. For +150: 150 / 100 + 1 = 2.50 decimal odds.
Use 100 / absolute American odds + 1. For -110: 100 / 110 + 1 = 1.909.
Decimal odds make parlay math easier (just multiply legs together) and are used by most international sportsbooks. Converting helps you compare lines across different platforms.