The **henry** (symbol H) is the SI unit of inductance. If the rate of change of current in a circuit is one ampere per second and the resulting electromotive force is one volt, then the inductance of the circuit is one henry.

The henry has dimensions V·A^{-1}·s = m²·kg·s^{-2}·A^{-2} in SI units.

The unit is named after the American scientist Joseph Henry.