# How to compute number of days in a year in Pandas

In our previous post we showed how to used the pendulum library in order to compute the number of days in a given year using the `pendulum` library.

This post shows how to achieve the same using `pandas`:

``````import pandas as pd
def number_of_days_in_year(year):
start = pd.Timestamp(year, 1, 1)
end = pd.Timestamp(year + 1, 1, 1)
return (end - start).days)
``````

#### Usage example:

``````print(number_of_days_in_year(2020)) # Prints 366
print(number_of_days_in_year(2021)) # Prints 365
``````

#### Explanation:

First, we define the `start` date to be the first day (1st of January) of the year we’re interested in:

``````start = pd.Timestamp(year, 1, 1)
``````

Now we generate the `end` date, which is the 1st of January of the following year:

``````end = pd.Timestamp(year + 1, 1, 1)
``````

The rest is simple: Just compute the difference (end - start) and ask pandas to give us the number of days:

``````(end - start).days
``````