About the Converter

The Converter is the contextual unit converter, currency converter and timezone converter for Firefox — experience the web with familiar metrics!

The Converter is a no-thrills tool. It aims to be intuitive for the average user during regular text reading. You can't specify the precision. You can't tweak the resulting units. You don't get the results in several formats. If you need any of that fancy stuff for scientific purposes you should probably use another tool.

Twitter Updates

→ follow the Converter on Twitter

How it works

The operation is as simple as possible, and it works in three distinct ways:

Single conversion on selection

Select a piece of text containing a measurement and right click: the converted value will be shown in the resulting pop-up menu.

Page conversion

Left-click on the Converter icon in the bottom-right corner: all measurements in the current web page are converted.

Custom conversions

Right-click on the Converter icon in the bottom-right corner, and choose "Custom conversion"—this way you can even convert offline measurements!

Check it out: install the Converter, and after restarting the browser select this entire paragraph and right click: 0.1 in = 2.54 mm is shown in the popup menu (that's because "0.1 in" is the first dimension encountered in this paragraph).

Features

Here's a comprehensive list of the Converter's main features:

• Large number of units and formats: Take a look at the examples page for a quick overview of the formats and units the Converter currently understands. Even more units will be supported in future versions.
• Small footprint: in spite of the relatively large assortment of units supported by the Converter, the final package is no larger than a few kilobytes.
• Fast, smart, intuitive operation: Since this tool aims at day-to-day, contextual operation, it performs quite a few tricks to come in handy with as little hassle as possible:

  The selection doesn't have to be accurate in the single conversion mode, just make sure you include the dimension you want converted, but you can include surrounding text as well: the Converter will identify the first dimension in there and convert it.

  The results are intuitive. For example the Converter doesn't simply convert metres to feet: 1,000,000 metres are converted to 621 miles.

  The input format is flexible. Some use the period as decimal separator, others use the comma. The thousands separator is even trickier: not only it can be either, but it's also optional. The Converter makes as many attempts to identify the proper format as possible, and only in really ambiguous situations it defaults to the de facto Internet standard, with period as the decimal separator.

  The units are flexible. The Converter can identify several notations for the same type of unit: m, meter, meters, metre and metres all identify the same unit and trigger the same conversion.

  The values can use fractions. Many texts include dimensions as fractions, for instance 1/10 m—the Converter evaluates fractions in the input.

  The wacky Imperial technical format is supported. Yes, 1'10-3/16" is properly converted. Take a look at the examples page for all the supported formats.

  You get feedback on what's being converted. With all the code interpreting your input, you may sometimes wonder what is the Converter parsing exactly. Don't worry, the Converter always shows you what it understood from the input before showing you the actual conversion.

  Ambiguous input is converted to your preferred units. Take 15 degrees for instance—are those centigrades or Fahrenheit? The Converter assumes ambiguous units to be the ones you're not familiar with (based on your preferencs) and converts them to what you're used to (if they happen to be the ones you are used to then you can use that, since you can always see the input as well).