Quarto could refer to:

• The book size which results when four leaves of the book are created from a standard size sheet of paper, a term used in bookbinding and publishing. Each leaf is usually printed on each side, so this creates a signature of 8 printed pages in total. In modern common usage, a quarto size book is 10-12" tall. It is often abbreviated as 4to, 4° or 4o.
• Quarto (board game), a board game for two players made by Family Games Inc.
• Quarto, Italy, a commune in the province of Naples
• Wikimedia Quarto, a quarterly newsletter published by the Wikimedia Foundation

Quarto | Quarto