App Smart

Weights or measures, converted on the fly

Do you automatically know how many kilograms are in a pound?

I do. It’s 0.45359237. I have to know this because I also write about tech outside the United States. While feet and pounds are used to measure some things in the United States, almost every other country has adopted the metric system.

You probably also convert units of currency, measurement, and more from one type to another often. Doing these calculations mentally can be tricky, so let an app do it.


$1 on iOS


The interface on Konvert, $1 on iOS, is extremely clear. It’s designed like a touchscreen calculator. It also requires more gestures to navigate its options and settings. It has a long list of unit types, and has some nice features — like animations that help you know where you are in the menus. But I find its gesture controls a little difficult to use when I’m trying to do quick unit conversions.


Free on Android

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Flib is a similar design-centric app. It is easy to use when converting units.

Flib’s visuals stand out. It even has a few neat extras like automatically putting the conversions you use most frequently at the top of its tile-like main menu. You can change its color scheme, ask the developers to add new conversions in future updates, and define how many decimal places you want to see.

One problem I had with Flib was using the Android “back” button instead of in-app controls to change menus because the back button was unpredictable.

Convert Everything/Convert Any Unit Free

Free on Android and iOS

For converting arcane or unusual units from one type to another, one great option is Convert Everything on Android.


It can convert units as common as length and as odd as wind chill or magnetic flux. The interface is a little strange, though: Instead of being organized via some sort of graphical control pad, each unit is listed in alphabetical order.

This can be confusing, but there’s a prominent search box so you can quickly find “feet” or “kilograms,” for example, and you can add a particular conversion to a favorites list.

Sometimes the app’s spartan interface can be a little confusing. But it is powerful, and it’s free.

Convert Any Unit Free on iOS is a rough equivalent to Convert Everything.

Its design is more pedestrian, but it does have some great features, like being able to define your own custom conversions. This is useful for advanced users, though I found the app to be a bit clunky.


Honorable mentions go to ConvertPad on Android, a free, ad-supported app; Unit Converter, which is free on Windows Phone; and Convert Units, which is free on iOS.

Typing a conversion query in the Google search bar in your browser can also get a quick answer to most unit conversion problems.

This is particularly easy on Android devices through Google Now. But it does require a network connection. Apps
generally provide a more elegant way to find this information.

Kit Eaton writes on technology
for The New York Times.