How accurate is python's time.sleep()?

I can give it floating point numbers, such as


but how accurate is it? If i give it


will it really sleep about 50 ms?


  • The accuracy of the time.sleep function depends on your underlying OS's sleep accuracy. For non-real-time OSs like a stock Windows, the smallest interval you can sleep for is about 10-13ms. I have seen accurate sleeps within several milliseconds of that time when above the minimum 10-13ms.

    Update: Like mentioned in the docs cited below, it's common to do the sleep in a loop that will make sure to go back to sleep if it wakes you up early.

    I should also mention that if you are running Ubuntu you can try out a pseudo real-time kernel (with the RT_PREEMPT patch set) by installing the rt kernel package (at least in Ubuntu 10.04 LTS).

    Non-real-time Linux kernels have minimum sleep intervals much closer to 1ms than 10ms, but it varies in a non-deterministic manner.