performance – How to measure elapsed time in Python?

If you just want to measure the elapsed wall-clock time between two points, you could use time.time():

import time

start = time.time()
print(hello)
end = time.time()
print(end - start)

This gives the execution time in seconds.

Another option since 3.3 might be to use perf_counter or process_time, depending on your requirements. Before 3.3 it was recommended to use time.clock (thanks Amber). However, it is currently deprecated:

On Unix, return the current processor time as a floating point number
expressed in seconds. The precision, and in fact the very definition
of the meaning of “processor time”, depends on that of the C function
of the same name.

On Windows, this function returns wall-clock seconds elapsed since the
first call to this function, as a floating point number, based on the
Win32 function QueryPerformanceCounter(). The resolution is typically
better than one microsecond.

Deprecated since version 3.3: The behaviour of this function depends
on the platform: use perf_counter() or process_time() instead,
depending on your requirements, to have a well defined behaviour.

Use timeit.default_timer instead of timeit.timeit. The former provides the best clock available on your platform and version of Python automatically:

from timeit import default_timer as timer

start = timer()
# ...
end = timer()
print(end - start) # Time in seconds, e.g. 5.38091952400282

timeit.default_timer is assigned to time.time() or time.clock() depending on OS. On Python 3.3+ default_timer is time.perf_counter() on all platforms. See Python – time.clock() vs. time.time() – accuracy?

See also:

• Optimizing code
• How to optimize for speed

performance – How to measure elapsed time in Python?

Python 3 only:

Since time.clock() is deprecated as of Python 3.3, you will want to use time.perf_counter() for system-wide timing, or time.process_time() for process-wide timing, just the way you used to use time.clock():

import time

t = time.process_time()
#do some stuff
elapsed_time = time.process_time() - t

The new function process_time will not include time elapsed during sleep.