杜隆-珀蒂定律（Dulong-Petit law）是物理学中描述结晶态固体由于晶格振动而具有的比热容的经典定律，由法国化学家皮埃尔·路易·杜隆（Pierre Louis Dulong）和阿列克西·泰雷兹·珀蒂（Alexis Thérèse Petit）于1819年提出。

定律的内容为：许多固体其摩尔比热容（单位焦耳／(开尔文·千克)）均为3R/MM，其中R为普适气体常数（单位焦耳／(开尔文·摩尔)）MM为摩尔质量（单位千克／摩尔）。换言之，晶体的无量纲热容恒等于3，其中C为总热容，n为摩尔数，N为包含的原子总数，k为玻尔兹曼常数。

The Dulong–Petit law, a thermodynamic rule proposed in 1819 by French physicists Pierre Louis Dulong and Alexis Thérèse Petit, states the classical expression for the molar specific heat capacity of certain chemical elements. Experimentally the two scientists had found that the heat capacity per weight (the mass-specific heat capacity) for a number of elements was close to a constant value, after it had been multiplied by a number representing the presumed relative atomic weight of the element. These atomic weights had shortly before been suggested by Dalton.