0° or 0 degrees may refer to:
- Longitude: the prime meridian on any planet or moon
- For most of the 20th century on Earth, the prime meridian (Greenwich)
- IERS Reference Meridian, the modern reference meridian for time and global navigation on Earth
- Latitude: the equator
- freezing point of water (Celsius)
- absolute zero, the lower limit of the thermodynamic temperature scale (Kelvins)
- 0 degrees Fahrenheit, approximately -17.78 degrees Celsius