Unit Converter by Moshi

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

• Weights — kg, g, mg, lb, lbs, oz, stone, ton, tonne
• Distances — km, m, cm, mm, miles, yards, feet/ft/', inches/in/" (including compound 5'10" notation)
• Temperatures — °F, °C, K — shows both other scales simultaneously
• Currency — symbol prefixes ($, £, €, ¥, …) and ISO codes (USD, EUR, GBP, …) — converts to your chosen target currency using live exchange rates

Just select text and the tooltip appears above the selection automatically.

Installation

Install from the Firefox Add-ons store.

Or load it manually for development — see Development below.

Usage

1. Select any text on a webpage that contains a measurement, e.g.:
2. 72°F → 22.222 °C | 295.372 K
3. 6'2" → 187.96 cm | 1.88 m
4. 180 lbs → 81.647 kg
5. $49.99 → 46.23 EUR (using live rates)
6. A tooltip appears above the selection with the converted value(s).
7. Click the toolbar icon to choose your target currency and refresh exchange rates.

Settings

Click the extension icon in the Firefox toolbar to open the settings popup:

• Target Currency — choose from 35+ currencies; conversions update immediately
• Refresh Exchange Rates — fetches the latest rates from open.er-api.com. Rates are also refreshed automatically every 6 hours.