Odds Calculator & Converter: Your Complete Guide
If you've ever placed a bet and felt lost staring at odds in different formats—decimal, fractional, American—you're not alone. Bookmakers love throwing numbers at us, but understanding what they actually mean can help you make better betting decisions.
Odds aren't just numbers—they represent probability. They tell us how likely an outcome is according to the bookmaker and what kind of return we can expect on a bet.
Understanding Betting Odds: Fractional, Decimal & American
Fractional Odds (Common in the UK & Ireland 🇬🇧)
Fractional odds (e.g., 5/1, pronounced "five to one") tell you how much profit you'll make relative to your stake.
Example: A £10 bet at 5/1 returns:
- Profit: £50 (£10 × 5)
- Total Payout: £60 (£50 profit + £10 stake)
Decimal Odds (Popular in Europe & Betting Exchanges 🇪🇺)
Decimal odds (e.g., 3.00) show the total return per £1 bet. This format is easier to work with when calculating winnings.
Example: A £10 bet at 3.00 returns:
- Profit: £20 (£10 × 3 - £10 stake)
- Total Payout: £30 (£10 × 3)
American Odds (Moneyline, Common in the US 🇺🇸)
American odds can look confusing at first, but they follow a simple rule:
- Positive odds (+): Show how much you'd win on a £100 bet.
- Negative odds (-): Show how much you need to bet to win £100 profit.
Example:
- +200 (Underdog): A £100 bet wins £200 (total return: £300).
- -150 (Favorite): You need to bet £150 to win £100 (total return: £250).
Implied Probability & How It Affects Your Bets
Every bet has an implied probability, which is just a fancy way of saying how often that bet is expected to win.
How to Calculate Implied Probability
- Fractional Odds → Probability: (1 / (Fractional Odds + 1)) × 100
- Decimal Odds → Probability: (1 / Decimal Odds) × 100
- American Odds:
- If positive: 100 / (American + 100) × 100
- If negative: (-American) / (-American + 100) × 100
How to Convert Betting Odds & Probability Instantly
Ever needed to convert odds but didn't know where to start? Here's a quick conversion guide:
| Convert From | To Decimal | To Fractional | To American |
|---|---|---|---|
| Fractional (5/1) | 6.00 | — | +500 |
| Decimal (2.50) | — | 3/2 | +150 |
| American (+200) | 3.00 | 2/1 | — |
If you don't want to do the math yourself, just use our Odds Calculator to get instant results. 🚀
How to Spot Value Bets & Make Smarter Wagers
Odds don't just tell you how much you'll win—they also tell you if a bet is worth taking. If the bookmaker gives you higher odds than the actual probability suggests, it might be a value bet.
Check out our Value Bets tool to find underpriced odds in real time.
Final Thoughts: Use Our Odds Calculator to Bet Smarter
Understanding how odds work is a game-changer in betting. Whether you're checking implied probability, converting odds, or just trying to make sense of American moneyline odds, getting comfortable with these numbers will help you make better, smarter bets.