${\displaystyle r=\frac{1}{\alpha }\frac{\text{d}c(\text{A})}{\text{d}t}=\frac{1}{\beta }\frac{\text{d}c(\text{B})}{\text{d}t}=\frac{1}{\sigma }\frac{\text{d}c(\text{S})}{\text{d}t}=\frac{1}{\tau }\frac{\text{d}c(\text{T})}{\text{d}t}}$

where A, B, ... denote reactants, S, T, ... denote products, −α, −β, …, σ, τ, … are the corresponding stoichiometric numbers, and c(A), c(B), …, c(S), c(T), … are the amount-of-substance concentrations of A, B, ... S, T, ..., respectively

Note 1 to entry: The coherent SI unit of reaction rate is mole per cubic metre second, mol m⁻³ s⁻¹.