Select the column or columns you want to autofit
Move your cursor to the right edge of a column header until it becomes a double-headed arrow
Double-click the right edge of the column header
To autofit multiple columns, select all desired columns first, then double-click any selected column boundary
To autofit all columns, select the entire worksheet and double-click any column boundary
Use the Home tab
Click Format in the Cells group
Select AutoFit Column Width
Use the keyboard shortcut Alt, H, O, I on Windows
On Mac, select the columns and use the Format menu or double-click the column boundary