Is the best calculator on Android a port of the Windows Calculator?

The Windows 10 calculator became open source in March of this year. Microsoft did this to "build an even better user experience in partnership with the community," according to the announcement post.

I'd imagine that Microsoft's intention was for users to build new features for the Windows Calculator on, well, Windows. The folks at Uno Platform decided to go in a different direction. They ported the Windows Calculator to Android (opens in new tab), iOS (opens in new tab), and the web using Uno Platform. I spoke with the higher-ups about Uno Calculator and the Uno Platform as a whole. Uno Calculator is a port of Windows Calculator so the feature set is identical to what you'd see on your PC. But it's a great chance to discuss Uno Platform and using code across platforms. The majority of my testing was on an Android phone, though I did try it a bit on the web.

A bit about the Uno Platform

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The Uno Platform allows developers to use C# and XAML code to create native apps on several platforms. Many native UWP apps use C#, so Uno Platform is one way that a developer could use their code from a Windows 10 application and bring it over to Android. But C# and XAML are by no means exclusively used by UWP developers. Developers familiar with these languages could create an app for mobile devices, the web, or PCs. Developers can also use the Uno Platform to deliver an app experience as a progressive web app (PWA) rather than a native application. Android and iOS apps using the Uno Platform rely heavily on the Xamarin Native stack. WebAssembly apps rely directly on the Mono-Wasm runtime.

I was extremely impressed by the folks at Uno Platform. We spoke extensively about the state of app development and how they've translated their experience with development to create Uno Platform. It's a clever idea that I must admit I'm surprised Microsoft didn't do themselves (they said they hear that a lot). If UWP app code could have been used to also create apps on other platforms, I think we may have seen UWP be more successful.

I was also surprised to hear that some UWP apps could be ported over to Windows in a day or two. However, this depends on the complexity of the application, and what code an app is made of. The Windows Calculator has code dating back into the 1990s, so it took weeks, rather than days to port it to the Android app.

How well does it actually work?

Ideas are fine and good, but they don't mean much if they don't work. I've tried dozens of applications that looked great in their descriptions or on paper but were terrible in practice. Additionally, I've seen bridge technologies perform poorly cough Facebook cough. Uno Calculator works well. It scales well in portrait and landscape mode and looks good in a split-screen view on my Galaxy S8+. The Windows Calculator has an extensive feature list, and all of them were ported over for Uno Calculator. It has standard, scientific, and programmer modes and also supports conversions including currency, weight, length, and other standard conversion tools. This feature list isn't groundbreaking since the Windows Calculator has supported them for a long time, but it's nice to see that everything works.

Microsoft can get the credit for creating the original calculator, but the port works well on Android. It takes a bit longer to boot up initially than the Samsung Calculator that came with my phone. Additionally, opening and closing the hamburger menu is a slower animation than I'd like. That being said, if you put this on most people's phones, they'd believe it was just a copy of the Windows Calculator. That's somewhat true of course, but making the port took a lot of work that end-users won't see. That's the point, though. An end-user shouldn't notice any difference between this app its siblings on iOS, the web, and its parent on Windows 10.

Is it the best calculator on Android?

I haven't used every calculator on Android, but I've looked into quite a few. Uno Calculator is certainly in the running for the best calculator available on Android phones. It has the power of a PC calculator that's been designed and improved by Microsoft for decades and has standard, scientific, and programmer modes. It also scales well and looks good. I find some calculators feel cramped on phones, but Uno Calculator uses the space well.

I certainly think Uno Calculator is a candidate for the best free calculator on Android. The app has no ads and a full feature set, though you could say that the app existing is an advertisement for the Uno Platform. The only complaints I have are that initial boot-up is a bit slow and that the menu animations take a beat too long.

Uno Calculator is a clever way to show off the Uno Platform. It's a port of an app that just about every Windows 10 user is familiar with. Even if you aren't looking for a new calculator, it's fun to use this one. It makes me feel like my Android phone is a bit more connected to Windows, which is nice for a Windows Phone convert like me.

Sean Endicott
News Writer and apps editor

Sean Endicott brings nearly a decade of experience covering Microsoft and Windows news to Windows Central. He joined our team in 2017 as an app reviewer and now heads up our day-to-day news coverage. If you have a news tip or an app to review, hit him up at (opens in new tab).

  • It is a nice calculator. It has more calculating features. As you mentioned, it is a bit slower than Samsung's. It's also lack dark mode. But very nice indeed.
  • The Uno Platform has been on my radar for some time now but i never find the time to test it. I think Microsoft themselves should have provided UWP developers with such option (to build for Android/iOS/Web) because they owe it to us (after the moronic decision to abandon their mobile OS)
  • MS should buy these guys and integrate ASAP.
  • yeah, exacttly this!
  • I'm definitely cheapskate when it comes to buying phones (I still miss Windows phone for its incredible performance on middling to low hardware, allowing brilliant, cheap devices like the Lumia 520 and 640). And on my Moto G this calculator is way too slow. Generally, when I want a calculator on my phone I expect to do a super-quick bit of math and get out again right away. For instance, if I'm shopping, or in a conversation where we don't want to do long multiplication in our heads etc. It needs to be FAST! And right now, as pretty as this port is, it's not at all usable because you sit and wait forever on it to load. It's also laggy just typing the numbers. I see a very visible delay between tapping a number and seeing it display on the screen, which makes me type everything quite slowly.
    Not ready for prime time on cheaper phones like a somewhat older Moto.
  • If your phone can’t run a calculator, then you have a crappy phone.
  • 26MB is too much for a calculator
  • Its laggy. The Android calculator is much better.
  • I have been looking for this for some time now. Dark mode is no where to be seen. Fix the lag and I will get rid of all other calculator apps I have installed.
  • Finally! I use at least once a week for volume conversations in imperial and percentage discounts.. Unless you've used the windows calculator, you couldn't understand how difficult it has been to find a reliable and trustworthy replacement calculator app.
  • Yep, it’s the Windows 10 calculator. Lots of functionality, but ugly and a very “my first app” appearance.
  • The complaints about slowness are just Samsung Android. I found everything to be slow on Samsung Android. It runs just fine on my iPhone 8 Plus. Even on my iPod touch, ready to use in under a second.
  • "I'd imagine that Microsoft's intention was for users to build new features for the Windows Calculator on, well, Windows."
    Why would you think that? Given MSs recent embrace of, well, pretty much everyone, I think they fully understood and intended for this open source code to wind up everywhere.
  • Finally a calculator app without ads.
  • Looking forward to futures updates on this app.