Etto may refer to:
- Etto (born 1981; Oélilton Araújo dos Santos), Brazilian soccer player
- Saint Etto (died 660); see Chronological list of saints in the 7th century
- etto (unit), a Sumatran traditional unit of measurement for length; see Indonesian units of measurement
- etto- (prefix), a non-standard metric prefix for 102
- -etto (suffix), an Italian language suffix for creating an Italian name using Italian grammar diminutive creation; see List of diminutives by language
- Etto principle, the efficiency–thoroughness trade-off principle]