PH-1, PH 1, PH.1, PH1 or variant, may refer to:
- PH1 (star system) (Planet Hunters 1), the first system with a planet (PH1b - Planet Hunters 1 b) discovered by Planet Hunters; the star system also called KIC 4862625 or Kepler-64
- Hall PH-1, a model of the Hall PH airplane
- PH1, a postcode in the PH postcode area of the United Kingdom
- PH1, IAU Minor Planet Center nomenclature for naming asteroids
- pH-1 (rapper), a South Korean rapper
- PH-1, the official codename for the Essential Phone, Andy Rubin's first-generation Android device