TL;DR
Use
my_timedelta / np.timedelta64(1, 's')
Full example
import pandas as pd import numpy as np import time # Create timedelta t1 = pd.Timestamp("now") time.sleep(3) t2 = pd.Timestamp("now") my_timedelta = t2 - t1 # Convert timedelta to seconds my_timedelta_in_seconds = my_timedelta / np.timedelta64(1, 's') print(my_timedelta_in_seconds) # prints 3.00154