What is the accuracy difference between `time.clock()` and `time.time()` in Python?

General Discussions
1

Which is better for timing in Python: time.clock() or time.time()? Which one provides more accuracy?

For example, consider the following two approaches:

start = time.clock()
# Do something
elapsed = time.clock() - start

vs.

start = time.time()
# Do something
elapsed = time.time() - start

When should you use time.clock in Python versus time.time() for timing, and which one is more accurate in different scenarios?

2

time.time() returns the current time in seconds since the epoch, with a floating-point value. It is more accurate and widely used for measuring elapsed time across different platforms. It works reliably on most operating systems and is not subject to platform-specific differences like time.clock().

Example :

import time

start = time.time()
# Perform some task
elapsed = time.time() - start
print(f"Elapsed time: {elapsed} seconds")

In most cases, time.time() is recommended because it is more consistent across platforms and provides reliable results for timing.

3

Although time.clock() was previously used for timing in Python, it has been deprecated in Python 3.8. For higher precision timing (especially in benchmarking scenarios), time.perf_counter() should be used. This function provides the highest available resolution clock for performance measurement.

Example:

import time

start = time.perf_counter()
# Perform some task
elapsed = time.perf_counter() - start
print(f"Elapsed time: {elapsed} seconds")

For performance measurement and more accurate results, time.perf_counter() is the most precise option.

4

Since time.clock() was removed in Python 3.8, it’s advisable not to use it for new Python code. It was platform-dependent, returning wall-clock time on some systems and CPU time on others, leading to inconsistent results.

The more robust alternative for time tracking is time.time() for general usage and time.perf_counter() for high-precision scenarios.

Example:

import time

# time.clock() is deprecated in Python 3.8 and above
# Using time.time() instead
start = time.time()
# Perform some task
elapsed = time.time() - start
print(f"Elapsed time: {elapsed} seconds")