10 Websites For Unit Conversions & Calculations

Saikat Basu 24-05-2011

The old bugbear of unit conversions confounds many. Sometimes it can be corrected with an eraser; sometimes it could take a million dollars. It is a matter of trivia that NASA’s 1999 loss of the $125 million Mars Climate Orbiter was caused by one launch team using metric units while another used US customary units for a calculation.


It is serious stuff and for long was a matter of national pride as the U.S and U.K went head to head with their measurement systems. Thankfully, the SI system became the universal standard. For me, it was just my homework and the headache of getting my pounds and pints right. Kilograms and liters (or is it litres?) seemed so much easier. Online unit converters and calculators save the day today. It’s no longer a case of 1,000,000 headaches = 1 mega-headache as online unit converters do the math with a click.

Here are ten of them.


unit conversions

It is an offbeat name for an all-in-one unit converter. The free online tool covers all the common conversions you might use in your daily life; some purely mathematical and others (clothing size, cooking) for functional. Exchange rate calculators again are one useful tool that gives you the currency conversions with a fair degree of real time accuracy.


unit of measure conversions


The free online converter handles temperature, volume, distance, weight, area, data, time, and speed unit conversions. The interface is very user-friendly with large icons and bulleted units which you can select for your instant conversion needs.

Convert Center

unit of measure conversions

Engineering students and others too can make use of the variety of conversion options on this site. Molar mass unit conversions or frequency wavelength unit conversions will appeal to the scientifically minded. I am more interested in finding out how many gallons I can get to the liter with the fuel conversion tool.

Convert World

unit of measure conversions

Advertisement ratchets up with a few more options like wind speed conversion, absorbed dose tool, TV & monitor size converter, and a ‘language’ conversion tool, among a lot of other scientific options. You can view the converters by selecting from your choice of 28 languages.

Conversion Tool

dimensions and unit calculations

This cool looking conversion tool supports just three measurements – Length, Temperature, and Weight. But if you are looking to equalize how the Americans say it as against the British, this simple tool should do the job quickly. Put in the figure, select the unit and out pops the equivalent measurement on the other scale.

Online Conversion

dimensions and unit calculations

Advertisement is another simple free online unit converter that has calculators relating to nearly 5,000 units, and 50,000 conversions. They are arranged in categories on the landing page. Check out the Miscellaneous category which has measurement tools for cholesterol, blood sugar, blood-alcohol content, GPA, wind chill, room area, typography, and a lot of other offbeat calculators.

Unit Converters

dimensions and unit calculations

Unit Converters is another simple site to the extent of its interface. Otherwise, the online service is chock-a-bloc with scientific and engineering unit converters ranging from the common to the more technical ones like radiology and magnetism.

Online Converter

10 Websites For Unit Conversions & Calculations unit converter08


The one unique conversion tool I found on this otherwise simple site is the tool that takes a piece of text and converts it into the dots and dashes of Morse Code. The other unit converters relate to the usual lineup of time, distance, pressure, energy and work, volume, speed etc.

Metric Conversions

10 Websites For Unit Conversions & Calculations unit converter09 is worth a mention not because it contains a unique conversion tool but because it is the only one I came across that lets you download ‘cheat sheets’ of conversion tables in printable formats. Inspite of the presence of one-click online tools, the printable downloads could serve as handy reference.

Converter (Firefox Add-on)

unit conversions

Converter is a useful Firefox add-on that works seamlessly with any figures you might have on the web page. It works via the right-click menu (select a figure and right click to see the options) or via the neat add-on bar where a single click converts all measurements on the page. You can also setup a custom conversion by right clicking on the icon on the add-on bar and entering your measurement values.

Of course, if you are an expert Google user, you can simply use the Google search bar How To Use Google As A Calculator Read More for some quick fire unit conversions and calculations. You can even use the powerful Wolfram Alpha 10 Search Terms To Put Wolfram Alpha To Good Use Everyday Read More engine. But these ten web tools do give you broader options. Each one of the ten tools brings something new to the table. Do you have your own free online unit conversion web app to add to the list?

Image Credit: Wikimedia Commons

Related topics: Calculator, Geeky Science.

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  1. Saikat
    December 27, 2014 at 5:06 am

    Covertiko looks very handy. Especially the clothing section. Google doesn't do that yet.

  2. tamir
    December 25, 2014 at 10:10 pm

    I too love Google because there is no need for searching in long lists.
    Another web app that supports human language like Google does is Convertiko:
    I've also used Wolfram but it's slower than those two.

  3. Ernst Gansner
    June 2, 2011 at 4:20 pm

    There are conversions and calculations for all units here:

    And other tools:

    Not sure why this was omitted?

  4. pceasies
    May 28, 2011 at 5:27 pm

    I've always used Google or Wolfram Alpha.

    For something common, just search Google, i.e.: "5 mi in km" and before the search results will be the conversion. For more complex thing try "500MiB at 15Kbps" at WolframAlpha for a time estimate.