File size increases after deleting some columns, why?

[dayanday]

I have two huge excel 2013 files (around 50MB) with a range of data and I notebook is so slow when I open those files.
I tried to deleted some columns, however the file was bigger. Why?

There's no pivot-table, just some ranges of data. Thanks.

 

[Useful]

how many columns, rows and sheets are includes in your wb?
(check for if there contains array formulas, conditional formatting, external linked cells, data validation, entire row or column formatted as whole and etc.)

Try to select all blank rows and columns and delete them (also use clear all option) and save your wb as ".xlsb".