How many frames per second does a standard cinema film run at?

How to get close to this number

Bracket it with perception. Below about ten frames a second, motion visibly stutters; above about sixty, most viewers stop detecting improvement. Film had to sit above the flicker threshold and as low as possible to save expensive stock, which puts the answer in the low twenties — and that is exactly where it landed.

The reason in the explanation is better than the reason people assume. The rate was not chosen for how motion looks; it was the slowest speed that gave acceptable sound quality on an optical soundtrack running alongside the picture. An aesthetic standard that has defined the look of cinema for a century was set by an audio constraint that no longer exists.

Which is why attempts to change it feel wrong rather than better. Higher frame rates produce motion that viewers describe as looking like video or like a television broadcast, because a century of association has made this rate mean "cinema". The figure is a convention that hardened into an aesthetic, and conventions of that age are almost impossible to move.