The Beaufort scale ( /ˈboʊfərt/) is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.

The scale was devised in 1805 by Francis Beaufort (later Rear Admiral Sir Francis Beaufort), an Irish-born Royal Navy officer, while serving on HMS Woolwich. The scale that carries Beaufort's name had a long and complex evolution, from the previous work of others, including Daniel Defoe the century before, to when Beaufort was a top administrator in the Royal Navy in the 1830s when it was adopted officially and first used during Darwin's voyage on HMS Beagle. In the early 19th century, naval officers made regular weather observations, but there was no standard scale and so they could be very subjective — one man's "stiff breeze" might be another's "soft breeze". Beaufort succeeded in standardizing the scale.

The initial scale of thirteen classes (zero to twelve) did not reference wind speed numbers but related qualitative wind conditions to effects on the sails of a man-of-war, then the main ship of the Royal Navy, from "just sufficient to give steerage" to "that which no canvas sails could withstand". At zero, all sails would be up; at six, half of the sails would have been taken down; and at twelve, all sails would be stowed away.