How to Add Days to Date in Pandas: Simple Guide

To add days to a date in pandas, use pd.to_timedelta() with the number of days and add it to your date column or Series. For example, df['date'] + pd.to_timedelta(5, unit='d') adds 5 days to each date.

Syntax

The basic syntax to add days to a pandas date column is:

• df['date_column'] + pd.to_timedelta(number_of_days, unit='d')

Here, df['date_column'] is your pandas Series with dates, number_of_days is how many days you want to add, and unit='d' means days.

python

df['date_column'] + pd.to_timedelta(3, unit='d')

Example

This example shows how to add 7 days to each date in a pandas DataFrame column.

python

import pandas as pd

dates = pd.to_datetime(['2024-01-01', '2024-02-15', '2024-03-10'])
df = pd.DataFrame({'date': dates})

# Add 7 days to each date

df['date_plus_7'] = df['date'] + pd.to_timedelta(7, unit='d')

print(df)

Output

        date date_plus_7
0 2024-01-01 2024-01-08
1 2024-02-15 2024-02-22
2 2024-03-10 2024-03-17

Common Pitfalls

One common mistake is trying to add an integer directly to a pandas datetime column, which causes an error. You must use pd.to_timedelta() to specify the time unit.

Wrong way:

df['date'] + 5  # This will raise an error

Right way:

df['date'] + pd.to_timedelta(5, unit='d')

python

import pandas as pd

dates = pd.to_datetime(['2024-01-01'])
df = pd.DataFrame({'date': dates})

# Wrong way (raises error)
# df['date'] + 5

# Correct way
result = df['date'] + pd.to_timedelta(5, unit='d')
print(result)

Output

0   2024-01-06
Name: date, dtype: datetime64[ns]

Quick Reference

Here is a quick cheat sheet for adding time to pandas dates:

Operation	Code Example	Description
Add days	df['date'] + pd.to_timedelta(3, unit='d')	Add 3 days to each date
Add hours	df['date'] + pd.to_timedelta(5, unit='h')	Add 5 hours to each date/time
Add minutes	df['date'] + pd.to_timedelta(10, unit='m')	Add 10 minutes
Add seconds	df['date'] + pd.to_timedelta(30, unit='s')	Add 30 seconds

Key Takeaways

Use pd.to_timedelta() to add days to pandas datetime columns safely.

Adding an integer directly to datetime columns causes errors.

Specify the unit as 'd' for days when using pd.to_timedelta().

You can add other time units like hours, minutes, and seconds similarly.

Always ensure your date column is in datetime format before adding days.