在矢量微积分中，弗莱纳公式(Frenet–Serret 公式)用来描述欧几里得空间R中的粒子在连续可微曲线上的运动。更具体的说，弗莱纳公式描述了曲线的切向，法向，副法方向之间的关系。

单位切矢量 T，单位法矢量 N，单位副法矢量 B，被称作 弗莱纳标架，他们的具体定义如下：

弗莱纳公式如下：

其中d/ds 是对弧长的微分， κ 为曲线的曲率，τ 为曲线的挠率。弗莱纳公式描述了空间曲线曲率挠率的变化规律。

In differential geometry, the Frenet–Serret formulas describe the kinematic properties of a particle moving along a continuous, differentiable curve in three-dimensional Euclidean space ℝ, or the geometric properties of the curve itself irrespective of any motion. More specifically, the formulas describe the derivatives of the so-called tangent, normal, and binormal unit vectors in terms of each other. The formulas are named after the two French mathematicians who independently discovered them: Jean Frédéric Frenet, in his thesis of 1847, and Joseph Alfred Serret in 1851. Vector notation and linear algebra currently used to write these formulas were not yet in use at the time of their discovery.