Equivalence theorem may refer to:
- Economics
- Ricardian equivalence, a principle in economics
- Revenue equivalence, a concept in auction theory
- Mathematics and physics
- Compass equivalence theorem, a theorem in straightedge and compass construction
- Equivalence principle, in general relativity
- Lax equivalence theorem, a theorem in the analysis of finite difference methods
- Optical equivalence theorem, a theorem in quantum optics
- Surface equivalence principle, a principle in electromagnetism and antenna theory