Odds converter
Decimal, fractional, American and implied probability — instantly.
Different books, different formats. Type a price in any format — decimal, fractional, American or a probability — and see all of them at once, including the implied probability the price bakes in. The fractional output uses the clean betting fraction punters actually recognise.
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What it does
- Decimal ⇄ fractional ⇄ American ⇄ implied probability
- Clean betting fractions (1.91 → 10/11)
- Implied probability for any price
- Accepts fractional input like 11/4
How to use it
- 1Pick the input format. Choose decimal, fractional, American or probability.
- 2Type the value. Enter the odds — e.g. 2.5, 11/4, +150 or 40.
- 3See every format. The converter shows all formats plus the implied probability.
What powers this
This calculator runs entirely in your browser. There's no account, no API key and no feed — nothing you type leaves the page. The maths is the same commodity matched-betting and value arithmetic used across the industry, implemented carefully and unit-tested.
Embed it on your site
Paste this where you want the odds converter to appear. The script auto-mounts every widget on the page; swap data-or-theme for light, dark or transparent.
<div data-or-widget="odds-converter" data-or-theme="light"></div>
<script src="https://oddsrelay.io/widgets/oddsrelay-widgets.js" async></script>Questions
- How do you convert decimal odds to a probability?
- Implied probability is 1 ÷ decimal odds. So 2.0 implies 50%, 4.0 implies 25%, and so on (before any bookmaker margin).
- Why is 1.91 shown as 10/11 and not 91/100?
- We approximate to the clean betting fraction punters use, rather than the literal decimal fraction. 10/11 is the recognised price; the exact decimal is still shown alongside it.
- How do American odds work?
- Positive American odds show the profit on a 100 stake (+150 → 2.5 decimal). Negative odds show the stake needed to win 100 (−200 → 1.5 decimal).
18+ · Data product for licensed operators. Please gamble responsibly.
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