# Unit Converter

> Select any text on a webpage containing a measurement and instantly see it converted in a tooltip. No clicking, no copy-pasting into a converter site.

Canonical page: [https://chrome-stats.com/d/unit-converter4](https://chrome-stats.com/d/unit-converter4)

## Overview

- **ID:** `unit-converter4`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Moshi
- **Category:** other
- **Daily users:** 5
- **Weekly downloads:** 1
- **Rating:** 5.00 / 5 (3 ratings)
- **Version:** 1.0.2
- **Last updated:** 2026-06-13
- **First published:** 2026-05-02
- **Size:** 32 KB
- **Data as of:** 2026-09-07
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/unit-converter4/)
- **Website:** [https://github.com/MoshiBin/firefox-converter](https://github.com/MoshiBin/firefox-converter)

## Description

Unit Converter — Firefox Extension

Select any text on a webpage containing a measurement and instantly see it converted in a tooltip. No clicking, no copy-pasting into a converter site.

Features
<ul><li><strong>Weights</strong> — <code>kg</code>, <code>g</code>, <code>mg</code>, <code>lb</code>, <code>lbs</code>, <code>oz</code>, <code>stone</code>, <code>ton</code>, <code>tonne</code></li><li><strong>Distances</strong> — <code>km</code>, <code>m</code>, <code>cm</code>, <code>mm</code>, <code>miles</code>, <code>yards</code>, <code>feet</code>/<code>ft</code>/<code>'</code>, <code>inches</code>/<code>in</code>/<code>"</code> (including compound <code>5'10"</code> notation)</li><li><strong>Temperatures</strong> — <code>°F</code>, <code>°C</code>, <code>K</code> — shows both other scales simultaneously</li><li><strong>Currency</strong> — symbol prefixes (<code>$</code>, <code>£</code>, <code>€</code>, <code>¥</code>, …) and ISO codes (<code>USD</code>, <code>EUR</code>, <code>GBP</code>, …) — converts to your chosen target currency using live exchange rates</li></ul>
Just select text and the tooltip appears above the selection automatically.

Installation

Install from the <a href="https://addons.mozilla.org/en-US/developers/addon/unit-converter4/" rel="nofollow">Firefox Add-ons store</a>.

Or load it manually for development — see <a href="/" rel="nofollow">Development</a> below.

Usage
<ol><li>Select any text on a webpage that contains a measurement, e.g.:</li><li><code>72°F</code> → <strong>22.222 °C | 295.372 K</strong></li><li><code>6'2"</code> → <strong>187.96 cm | 1.88 m</strong></li><li><code>180 lbs</code> → <strong>81.647 kg</strong></li><li><code>$49.99</code> → <strong>46.23 EUR</strong> <em>(using live rates)</em></li><li>A tooltip appears above the selection with the converted value(s).</li><li>Click the toolbar icon to choose your <strong>target currency</strong> and refresh exchange rates.</li></ol>
Settings

Click the extension icon in the Firefox toolbar to open the settings popup:
<ul><li><strong>Target Currency</strong> — choose from 35+ currencies; conversions update immediately</li><li><strong>Refresh Exchange Rates</strong> — fetches the latest rates from <a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/6b97675102a133a85b960cef2bdaddc8424928f95a71a73479b4ba0726d809f0/https%3A//open.er-api.com" rel="nofollow">open.er-api.com</a>. Rates are also refreshed automatically every 6 hours.</li></ul>

## Rankings

- #43,154 — Overall
- #133 — temperature
- #148 — united
- #189 — convert

## Permissions and access

### Permissions

- `storage`
- `activeTab`

### Content script matches

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/unit-converter4)