1/5 may refer to:
- January 5, the date
- 1 May, the date
- quintile, a 5-quantile in statistics
- one fifth, the reciprocal of the number 5, = 0.2
- one and five, 1 shilling and 5 pence in pre-decimal British Coinage
- 1st Battalion 5th Marines
- one to five betting odds