iOS 11’s Calculator app suffers from input lag if you type too quickly

Apple’s stock Calculator app that comes preloaded on iPhone and iPod touch is apparently plagued with an issue that causes input to be lost if you type too quickly.

This appears to be unique to iOS 11.

According to a long thread on Reddit (via Loop Insight), the issue appears to stem from the fact that the app blocks all input during the animation for the button fades.

This causes it to not register key taps until the animation finishes.

If I had to guess, I’d say this is an iOS problem rather than an isolated Calculator issue. Although iOS 11 betas did allow for taps to register before a UI animation finished playing, that behavior changed in the commercial release of iOS 11.

I can confirm that this is not fixed in the most recent beta of iOS 11.1. I tried Calculator on iOS 10.x and there was no input lag whatsoever.

Clearly this is yet another design oversight in iOS 11 that may or may not be addressed in one of the future iOS software updates. You can, of course, tell Apple how dissatisfied you are with this by filing a bug report at

Have you noticed this Calculator issue before?

When I first encountered it, I thought maybe it had something to do with upgrading to iOS 11 versus performing a clean install of iOS. However, later I did reinstall iOS 11 from scratch and the issue still persists. That being said, I was never too concerned about the input lag because I use the excellent PCalc app for all my math needs.

Have you noticed this bug yet?

And while we’re at it, what’s your favorite Calculator replacement?