埃格斯特朗（Ångström, 简称埃，符号Å）是一个长度单位。它不是国际制单位，但是可与国际制单位进行换算，即1 Å = 10 米 = 0.1纳米。它一般用于原子半径、化学键长和可见光的波长。原子的共价半径在0.3埃（氢）和1.7埃（铀，最重的天然元素）之间。它还被广泛应用于结构生物学。

埃格斯特朗这个单位是为了纪念瑞典科学家安德斯·埃格斯特朗而命名的。埃格斯特朗是光谱学的创始人之一，他为太阳光谱的辐射波长制作了谱图，即以埃为单位。他同时也钻研热传导、地磁学和北极光。

The ångström (Swedish: [ˈɔŋstrøm]) or angstrom is a unit of length equal to 6990100000000000000♠10 m (one ten-billionth of a metre) or 6990100000000000000♠0.1 nm. Its symbol is Å, a letter in the Swedish alphabet.

The natural sciences and technology often use ångström to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. Atoms of phosphorus, sulfur, and chlorine are about an ångström in covalent radius, while a hydrogen atom is about half an ångström; see atomic radius.