Odds Converter & Calculator
Convert betting odds between American (+150 / −110), Decimal (2.50), Fractional (3/2), and Implied Probability (40%). Free, instant, no signup — the same odds calculator used by thousands of sports bettors daily.
How odds conversion works
- American → Decimal: Positive: (odds / 100) + 1. Negative: (100 / |odds|) + 1.
- Decimal → Implied %: 1 / decimal × 100.
- Fractional → Decimal: (numerator / denominator) + 1. So 3/2 = 2.50.
- Implied → Fair odds: If you think a team wins -122 of the time, the fair American price is -122.
Quick reference: common odds conversions
| American | Decimal | Fractional | Implied % |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.67% |
| -150 | 1.67 | 2/3 | 60.00% |
| -110 | 1.91 | 10/11 | 52.38% |
| +100 | 2.00 | 1/1 | 50.00% |
| +150 | 2.50 | 3/2 | 40.00% |
| +200 | 3.00 | 2/1 | 33.33% |
| +300 | 4.00 | 3/1 | 25.00% |
| +500 | 6.00 | 5/1 | 16.67% |
Why bettors convert odds
American odds are standard at US sportsbooks (DraftKings, FanDuel, BetMGM, Caesars). Decimal odds dominate Europe, Australia, and most exchanges (Pinnacle, Betfair). Fractional odds are the UK horse racing standard. Implied probability is the one number that actually matters when you're hunting +EV — it tells you the break-even win rate baked into a price.
If a sportsbook prices a team at −110, you need to win 52.38% of the time just to break even. If you think the true probability is 55%, you have a roughly 2.6% edge — that's the math every value bettor runs before placing a wager. Use this odds converter to translate any sportsbook's price into the format you reason in fastest, then run it through our bet grader or EV calculator.
Frequently asked questions
How do you convert American odds to decimal?
For positive American odds, divide by 100 and add 1 — so +150 becomes 2.50. For negative odds, divide 100 by the absolute value and add 1 — so −110 becomes 1.909. Our converter does it instantly.
How do you convert odds to implied probability?
Take 1 divided by the decimal odds, then multiply by 100. Decimal 2.50 = 1 / 2.50 = 0.40 = 40% implied win probability. That percentage is the break-even win rate you need to profit at that price.
How do you convert American odds to probability?
Positive odds: 100 / (odds + 100). So +150 → 100 / 250 = 40%. Negative odds: |odds| / (|odds| + 100). So −110 → 110 / 210 = 52.38%. This is the implied probability the sportsbook is pricing in (vig included).
How do you convert decimal odds to American?
If decimal is 2.00 or higher: (decimal − 1) × 100, written as positive (e.g. 2.50 → +150). If lower than 2.00: −100 / (decimal − 1), written as negative (e.g. 1.50 → −200).
How do you convert fractional odds to decimal?
Divide the numerator by the denominator and add 1. So 3/2 (three-to-two) = 1.5 + 1 = 2.50 decimal, which equals +150 American.
Is this odds calculator free?
Yes — every conversion (American, decimal, fractional, implied probability) is free, instant, with no signup. Bettors use it daily alongside our bet grader, EV calculator, and parlay calculator.