In feudal Anglo-Norman England and Ireland, a knight's fee was a unit measure of land deemed sufficient to support a knight. It would not only provide sustenance for himself, his family, and servants, but also the means to furnish himself and his retinue with horses and armour to fight for his overlord in battle. It was effectively the size of a fief (or "fee" which is synonymous with "fief") sufficient to support one knight in the ongoing performance of his feudal duties (knight-service).
A knight's fee cannot be stated as a standard number of acres, as the required acreage to produce a given crop or revenue would vary depending on many factors, including its location, the richness of its soil and the local climate, as well as the presence of other exploitable resources such as a fishing weir, quarries of rock, or mines of minerals. If a knight's fee is deemed coterminous with a manor, an average size would be between 1,000 and 5,000 acres, of which much in early times was still "waste", forest and uncultivated moorland.
