Last updated: 2026-04-30

Area Units

Area is a two-dimensional measure of a surface, expressed as the square of a linear unit. Squaring the unit also squares the scale difference between systems: the metric world uses square meters or hectares for real estate; the US uses square feet and acres.

This converter handles the metric ladder (mm² → km²) and imperial-customary units (square inch, square foot, acre, square mile).

Conversion Reference

All conversions use the SI square meter as the pivot. Imperial values are exact via the 1959 inch (0.0254 m).

From	To square meters	Notes
1 cm²	0.000 1
1 hectare (ha)	10,000	100 m × 100 m
1 are (a)	100	10 m × 10 m
1 km²	1,000,000
1 in²	0.000 645 16	Exact
1 ft²	0.092 903 04	Exact
1 yd²	0.836 127 36	Exact
1 acre	4,046.856 422	1/640 of a square mile (a "section")
1 mi²	2,589,988.110 336	640 acres

When Each Unit Shows Up

Square meters are the default for room sizes, apartments, and small commercial space worldwide. Hectares dominate farmland, parks, and any "moderate parcel" — easy to grasp because one hectare is roughly the area of a soccer field.

Square feet rule US real estate listings ("a 1,200 sq ft house"). Acres appear in US/UK rural land, parks ("Central Park is 843 acres"), and golf courses. Square miles apply to cities, counties, and large nature reserves.

Frequently Asked Questions (FAQ)

What is the difference between an are and a hectare?

An are is 100 m² (a 10 m × 10 m square) and a hectare is 10,000 m² (a 100 m × 100 m square — 100 ares). The hectare is the practical farm-and-park unit; the are is rare today outside formal European land records.

Why is one acre such an odd number of square meters?

The acre originated as the area a yoke of oxen could plough in a day — one furlong (220 yd) long by one chain (22 yd) wide. That gives 4,840 sq yd, which converts to 4,046.856 422 m². Old units rarely round nicely in metric.