Sum rule may refer to:
Sum rule in differentiation, Differentiation rules #Differentiation is linear Sum rule in integration, see Integral #Properties Addition principle, a counting principle in combinatorics In probability theory, an implication of the additivity axiom, see Probability axioms #Further consequences Sum rule in quantum mechanics QCD sum rules, non-perturbative techniques in quantum chromodynamics Sum rules (quantum field theory), relations between static and dynamic quantities in quantum field theory