>>> flights.isna().mean().round(4) * 100
In [1]: s = pd.Series([1,2,3, np.nan, np.nan])
In [4]: s.isna().sum() # or s.isnull().sum() for older pandas versions
Out[4]: 2
df.isna().sum().sum()
import pandas as pd
## df1 as an example data frame
## col1 name of column for which you want to calculate the nan values
sum(pd.isnull(df1['col1']))