---
url: "https://predictiontoolkit.com/tools/polymarketoddsconverter-extension/"
publisher: "PredictionToolkit"
dateModified: "2026-11-02"
---

[← Browser extensions](<https://predictiontoolkit.com/polymarket-browser-extensions/>) 

Browser extension

# PolymarketOddsConverter (extension): Decimal Odds Display for Chrome and Firefox

PolymarketOddsConverter is a locally installed Chrome or Firefox extension for changing the displayed odds format. It converts visible implied probabilities into decimal odds without changing the contract or order book.

[**3.0**/ 5Editorial rating](<https://predictiontoolkit.com/tools/polymarketoddsconverter-extension/#reviews>) [Editorial assessment](<https://predictiontoolkit.com/tools/polymarketoddsconverter-extension/#reviews>) 

[Open the PolymarketOddsConverter repository](<https://github.com/grigolin/polymarketoddsconverter>) github.com

**Pricing:** No subscription or paid unlock is listed. Install manually through browser extension developer tools.

[Screenshots](<https://predictiontoolkit.com/tools/polymarketoddsconverter-extension/#screenshots>) [Explore alternatives](<https://predictiontoolkit.com/tools/polymarketoddsconverter-extension/#alternatives>) 

[Browser extensions](<https://predictiontoolkit.com/polymarket-browser-extensions/>) 

## Screenshots and interface

Product preview1 / 2

Provider illustration of the display conversion.

## What is PolymarketOddsConverter (extension)?

The toolbar icon switches conversion on or off, letting users compare familiar sportsbook-style decimals with probability. Decimal odds are the reciprocal of probability expressed as a fraction; this gross display does not incorporate fees or liquidity.

Installation uses the repository and browser developer tools rather than a hosted account. Chrome and Firefox have separate manifests and background implementations. The Firefox instructions describe a temporary add-on, and Polymarket layout changes can affect an extension that rewrites displayed values.

### Who it is for

-   Users familiar with decimal sportsbook odds.
-   People comparing display formats.
-   Users comfortable loading unpacked extensions.

## Browser tools and permissions

-   **Decimal display**
    
    Convert visible implied probabilities to decimal odds.
    
-   **Toolbar toggle**
    
    Enable or disable conversion without removing the extension.
    
-   **Chrome**
    
    Browser-specific manifest and service-worker background.
    
-   **Firefox**
    
    Separate manifest and background script.
    
-   **Local install**
    
    Load repository files without a hosted account.
    

## Browser workflows

### Read familiar units

Install the correct browser version, open Polymarket and toggle the display.

### Compare formats

Switch between representations while keeping the original contract rules visible.

## Pricing and total cost

No subscription or paid unlock is listed. Install manually through browser extension developer tools.

## Installation and permissions

1.  Download the repository.
2.  Rename the chosen browser manifest to manifest.json in that copy.
3.  In Chrome, enable Developer mode and load the unpacked directory.
4.  In Firefox, load a temporary add-on through the debugging page.
5.  Open Polymarket and check the toolbar toggle.

Chrome and Firefox require different manifests.

## Useful links

### What to check

-   Firefox installation is temporary in the documented route.
-   Conversion changes presentation only; fees and liquidity still matter.
-   Page-layout changes can disrupt value rewriting.

A closer look

## Ratings & reviews

Editorial rating

**3.0**/ 5

0 user reviews

PredictionToolkit editorial

### Our take on PolymarketOddsConverter (extension)

A simple toggle solves a clear display need. Manual installation, temporary Firefox loading and layout dependence add maintenance work.

**Assessment criteria:** Task usefulness, documented scope, setup clarity, and access and cost transparency.

**Assessment date:** 2026-10-01

**Documentation reviewed:** 2026-10-01

Documentation-based assessment. [How we rate](<https://predictiontoolkit.com/methodology/>) 

### User reviews 0

The main score switches to user ratings after 5 published reviews.

**Be the first to share your experience**

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## Frequently asked questions about PolymarketOddsConverter (extension)

### Does it change order prices?

No. Only presentation changes.

### How are the formats related?

Gross decimal odds are the reciprocal of probability expressed as a fraction.

### Can I disable it quickly?

Use the toolbar icon.

### Can both browsers share a manifest?

The repository supplies separate Chrome and Firefox manifests.

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