Everything Metric (Auto Unit Converter) by Milos

This add-on automatically translates all sites from American units to International System of units (SI/Metric), adding converted unit in brackets behind USC units.

Example: 10 feet 🠚 10 feet【𝟯 𝗺】

Convenient for Amazon shopping, cooking, etc.

Inch, Feet, Yard, Mile -> Metre (Meter)
Pound, Ounce, Stone -> Kilogram
Gallon, Quart, Pint, Fluid Ounces, Cups -> Litre (Liter)
mpg -> L/100 km
mph -> km/h
Fahrenheit -> Celsius
Area conversion for ft, yd, in, mi, both as "sq. ft" and "ft²" (must not be superscript); the same is for volume conversion.

Toolbar button to turn ON/OFF globally
Shortcut Alt+M to force conversion (You can keep extension off, and only press the shortcut when you'd like page converted)

Don't forget to check Options page.

Not working on a specific site? Have a suggestion for improvement?
Send me an email with details.

Now open source, contribute to code at https://github.com/m1l/Everything-Metric-Firefox
or contribute with a coffee for the developer at https://paypal.me/milospa

Permission to read page data is required to be able to modify page text to add metric units.
Permission to storage is required to save settings.