Toggles bold on the selection, or on the selected text while editing.

Windows

Ctrl + B

Mac

⌘ + B

• Bold headers

  Select the header row, Ctrl + B → Bold headers

  The first formatting anyone learns.

• Bold part of a cell

  F2, select part of the text, Ctrl + B → Only that part is bold

  Partial formatting inside a cell.

• Unbold

  Ctrl + B on bold cells → Bold removed

  It toggles.

• Ctrl + I and Ctrl + U for italic and underline.
• Bold totals and headers only; bold everywhere is bold nowhere.
• Format Painter copies the whole style.

• Partial-cell formatting is lost if the cell is later given a formula.
• Toggling a mixed selection makes everything bold first.