How to AutoFit Columns in Excel: every column the right width

Columns too narrow show #### for numbers and cut off text. AutoFit sizes each column to its longest entry.

One column

Move the mouse to the line between two column letters (A and B) until it becomes a double arrow. Double-click.

Every column on the sheet

1. Click the corner triangle (top-left) to select all, or Ctrl + A twice.
2. Double-click any line between two column letters.

Every column resizes at once.

Keyboard

Select the columns, then press Alt, H, O, I one after the other (not together). Rows: Alt, H, O, A.

Set a fixed width instead

Select the columns › right-click a letter › Column Width › type 15 › OK.

Check it worked

No #### anywhere; every heading fully visible.

Why it sometimes goes wrong

One huge cell. A paragraph in A50 makes column A enormous. Turn on Wrap Text for that cell first, or set a fixed width.

Merged cells are ignored by AutoFit. Unmerge, or size by hand.

Heading row is bigger than the data. Select only the data rows before double-clicking; AutoFit uses the selection.

AutoFit rows too

Select the rows, double-click the line between two row numbers. Needed after turning on Wrap Text.