Betting Odds Converter

Convert American, Decimal & Fractional odds instantly.

Convert sports betting odds between American (moneyline, e.g. -110 / +150), Decimal (e.g. 1.91) and Fractional (e.g. 10/11) formats instantly. Type odds in whichever format your sportsbook uses and see all three side by side, plus the implied win probability those odds represent. Runs fully in your browser — nothing is uploaded.

Betting Odds Converter features

• Convert American ⇄ Decimal ⇄ Fractional odds instantly
• Implied win probability for any odds
• Favorite (−) / Underdog (+) toggle for American odds
• Shareable result link
• 100% free, in-browser, no sign-up

How to use Betting Odds Converter

1. Pick the format you have

   Choose American, Decimal or Fractional from the tabs, matching however your sportsbook displays the odds.

2. Type the number

   For American odds, toggle Favorite (−) or Underdog (+) and enter the number, e.g. 110 for -110. For decimal, type 1.91. For fractional, enter the numerator and denominator, e.g. 10/11.

3. Read every format at once

   This betting odds converter instantly shows the same price in all three formats, plus the implied win probability those odds bake in.

4. Switch formats anytime

   Change the format tab and your number carries over automatically — useful when comparing a US sportsbook (American) against a UK/European one (Fractional/Decimal).

Tricks & interesting facts

Reading American odds at a glance

The sign alone tells you who's favored — no conversion needed for that much.

• TIP A minus sign (e.g. -150) means that side is the favorite — you risk more than you'd win.
• TIP A plus sign (e.g. +150) means that side is the underdog — a $100 bet wins more than $100.
• FACT +100 / -100 (2.00 decimal, 1/1 fractional) is an exact 50/50 coin-flip price — the one number where all three formats look almost identical.

Quick mental shortcut: for negative American odds, add 100 to the number and you're close to the implied win % — e.g. -110 → 110/210 ≈ 52%.

Why -110 is everywhere in US sports betting

Almost every point-spread and total offered by a US sportsbook is priced at -110 on both sides.

• FACT -110 on both sides adds up to about 104.5% implied probability — the extra 4.5% is the sportsbook's built-in profit margin, called the 'vig'.
• FACT Because of that vig, you actually need to win more than 52.4% of your -110 bets just to break even long-term — not 50%.

Frequently asked questions

How do I convert American odds to decimal?

For positive American odds, Decimal = (American ÷ 100) + 1 — e.g. +150 becomes 2.50. For negative American odds, Decimal = (100 ÷ |American|) + 1 — e.g. -110 becomes 1.91.

How do I convert decimal odds to fractional?

Subtract 1 from the decimal odds, then express the result as the simplest fraction — e.g. decimal 1.91 (0.91) reduces to 10/11; decimal 2.50 (1.50) reduces to 3/2.

What does -110 mean in betting?

-110 is American odds meaning you must stake $110 to win $100 profit ($210 total return). It converts to 1.91 decimal and 10/11 fractional, and implies a 52.4% win probability before the vig is removed.

What does +150 mean in betting?

+150 is American odds meaning a $100 stake wins $150 profit ($250 total return). It converts to 2.50 decimal and 3/2 fractional, implying a 40% win probability before the vig is removed.

Why do American, Decimal and Fractional odds all look so different?

They're three ways of expressing the exact same price. American shows profit relative to a $100 (or $100-to-win) stake, Decimal shows total return per $1 staked (including your stake back), and Fractional shows profit relative to the stake as a ratio. This converter proves they're mathematically identical.

What is implied probability in betting odds?

It's the win chance the odds mathematically represent: 1 ÷ decimal odds, as a percentage. It's not the sportsbook's true prediction — it includes their vig (margin), so it's always a little higher than the fair probability of the outcome.

Is this odds converter free?

Yes — it's a free, unlimited, 100% in-browser calculator. No sign-up, no API calls, nothing is uploaded.

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