Centigrade to Fahrenheit, miles to kilometres, pounds to kilogrammes – everyone needs a unit conversion tool occasionally. And if you’re working with simple units, and are online at the time, then a quick web search will probably find a service to help. Or you can often use Google directly: just type 55F in C into the search box for a quick temperature conversion, for instance.

If you’d like some offline assistance, though, or need to run more unusual conversions, then the free ESBUnitConv is a great place to start.

Setup is very easy. There’s no adware here, no toolbars. The developer has a commercial Pro version available, but the free edition doesn’t include nag screens or other marketing irritations. ESBUnitConv is portable, so all you have to do is unzip the download. And it’s a single executable with no .NET or other big dependencies, which means you can run it on anything from Windows 98-8.

Once you've found your measurement units, conversion is very easy

The program’s main interface organises its conversion types into 21 tabs, which cover everything from distance, temperature and mass, to energy, illumination and radioactivity. And clicking any of these reveals a (usually) lengthy list of units. The Distance section, for instance, doesn’t just have centimetres, feet, meters, and so on; you also get anstroms, chains, fathoms, light years, parsecs and a whole lot more.

Obviously this can look a little intimidating, at least initially, but in real life use it doesn’t make much difference. Units are sorted into alphabetical order, so to convert fathoms to miles, say, you’d click the Distance tab, then just scroll past everything else to select “Fathoms” and “Miles” in the “From” and “To” lists. Finally, type the figure you’d like to convert and ESBUnitConv will display the equivalent for you (clicking the Copy button, if necessary, will send this to the clipboard).

And there’s also a neat extra in the shape of a small but convenient pop-up scientific calculator. If you need to run a few calculations to find that initial “From” value, click the calculator button, and go to work. When you’re done, click “Exit and transfer result” and your final figure will appear in the program’s “From” box.

The sheer number of measurement units here mean ESBUnitConv isn’t going to be for everyone. But there’s no doubt the program is compact, highly portable and very convenient to use, and if you need more power than Google and more basic tools have to offer then it’ll probably be able to help.