NH4 or NH-4 or NH 4 may refer to:
- Ammonium, the NH+
4 ion in chemistry - National Highway 4 (India), a major National Highway in western and southern India
- New Hampshire Route 4, a 3.78-mile (6.08 km) long state highway located in eastern Strafford County, New Hampshire, USA
- New Hampshire's 4th congressional district, an obsolete electoral district in New Hampshire, USA
- NH4 (film), an upcoming Indian film