Quarto has several meanings:
- In bookbinding and publishing, quarto indicates the book size which results when four leaves of the book are created from a standard size sheet of paper. 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. Often abbreviated as 4to, 4° or 4o.
- Quarto is a board game for two players made by Family Games Inc.
- Quarto, Italy (pronunciation: KWAHR-toh, pop: 35,434, area: 14 km², postal code: 80010), a commune in the province of Naples
- Wikimedia Quarto is a multilingual quarterly newsletter published by the Wikimedia Foundation, Inc. It can be read online here