Guide

Areas in everyday life: square metres, hectares and acres

Areas appear in land registers, property listings, construction drawings and agricultural data. Metric and Anglo-American units do not sit in the same order of magnitude, and regional measures such as the German Morgen have no fixed definition at all.

The base unit is the square metre

Every area unit relates to the square metre through a fixed factor. One are is 100 m², one hectare 10,000 m², one square kilometre 1,000,000 m². Because these are areas, the factor grows with the square of the length: a square with twice the side length has four times the area.

Acre, square foot and square inch

The acre belongs to the Anglo-American system and is not metrically defined: 1 acre = 4046.8564224 m², about 0.4047 hectares. One square foot is 0.09290304 m², one square inch 6.4516 cm². The awkward values arise because these units derive from foot and inch, and a foot measures 0.3048 metres.

Regional measures without a fixed size

The Morgen, Tagwerk, Juchart and similar measures are historical area units without a uniform definition. Depending on the region the Morgen ranged from roughly 2500 to 12,000 square metres. Such figures cannot be converted into a fixed number of square metres, which is exactly why they are not in the conversion table.

Living area, footprint and usable area

For property the living area is the countable floor area of the rooms, the footprint the built-over area of the building and the usable area the areas actually available for use. The three figures differ considerably, and figures without a label are not comparable. Unit arithmetic only converts; it does not define which area counts.

Matching conversions

Matching tables

Unit family: Area

Sources