Write a Python function to calculate the total number of business days from a range of start and end date

Business days are weekdays (Monday through Friday), excluding weekends and holidays. Python's Pandas library provides several methods to calculate business days between two dates.

Understanding Business Days

First, let's see what business days look like in a date range ?

import pandas as pd

dates = pd.bdate_range('2020-01-01', '2020-01-31')
print("Business days in January 2020:")
print(dates)
print(f"Total business days: {len(dates)}")

Business days in January 2020:
DatetimeIndex(['2020-01-01', '2020-01-02', '2020-01-03', '2020-01-06',
               '2020-01-07', '2020-01-08', '2020-01-09', '2020-01-10',
               '2020-01-13', '2020-01-14', '2020-01-15', '2020-01-16',
               '2020-01-17', '2020-01-20', '2020-01-21', '2020-01-22',
               '2020-01-23', '2020-01-24', '2020-01-27', '2020-01-28',
               '2020-01-29', '2020-01-30', '2020-01-31'],
              dtype='datetime64[ns]', freq='B')
Total business days: 23

Method 1: Using bdate_range() with len()

The most efficient approach uses Pandas' bdate_range() function ?

import pandas as pd

def count_business_days(start_date, end_date):
    dates = pd.bdate_range(start_date, end_date)
    return len(dates)

# Example usage
start = '2020-01-01'
end = '2020-02-02'
business_days = count_business_days(start, end)
print(f"Business days from {start} to {end}: {business_days}")

Business days from 2020-01-01 to 2020-02-02: 23

Method 2: Using Manual Counting

You can also count business days by iterating through the date range ?

import pandas as pd

def count_business_days_manual(start_date, end_date):
    dates = pd.bdate_range(start_date, end_date)
    count = 0
    for date in dates:
        count += 1
    return count

# Example usage
start = '2020-01-01'
end = '2020-02-02'
business_days = count_business_days_manual(start, end)
print(f"Business days from {start} to {end}: {business_days}")

Business days from 2020-01-01 to 2020-02-02: 23

Method 3: Using NumPy's busday_count()

NumPy also provides a direct function to count business days ?

import numpy as np

def count_business_days_numpy(start_date, end_date):
    return np.busday_count(start_date, end_date)

# Example usage
start = '2020-01-01'
end = '2020-02-02'
business_days = count_business_days_numpy(start, end)
print(f"Business days from {start} to {end}: {business_days}")

Business days from 2020-01-01 to 2020-02-02: 22

Comparison

Conclusion

Use pd.bdate_range() with len() for most business day calculations. For maximum performance with large date ranges, consider np.busday_count(), but note it excludes the end date.