埃朗（英语：Erlang，简写为 E）是无量纲计量单位之一，广泛用于统计电讯流量大小上。如果某通信系统采用一个频道，在无间断持续及资源满载的情况下，其流量为1个埃朗单位。如果有两条频道，每条频道有50%资源被持续使用，又或是全数资源在一天内持续使用半天，其流量也是1个埃朗单位。

1946年，为表扬丹麦电讯工程师Agner Krarup Erlang的理论贡献，CCITT以他的名字来作为计量单位名称。

The erlang (symbol E) is a dimensionless unit that is used in telephony as a measure of offered load or carried load on service-providing elements such as telephone circuits or telephone switching equipment. For example, a single cord circuit has the capacity to be used for 60 minutes in one hour. If one hundred six-minute calls are received on a group of such circuits, then assuming no other calls are placed for the rest of the hour, the total traffic in that hour will be six hundred minutes, or 10 erlangs.