Converting Area: Square Metres, Square Feet and Acres

Floor plans, gardens, building plots and listings all state area — but rarely in the unit you want. Converting between square metres, square feet, acres and hectares is easy once you spot the one rule that catches everyone out: area factors are not the same as length factors.

Why you square the factor

A foot is 0.3048 metres, so it's tempting to convert square feet to square metres with the same number. It doesn't work. Area is length times length, so you convert with the square of the length factor. Since 1 ft = 0.3048 m, one square foot is 0.3048 × 0.3048 = about 0.0929 m².

A worked example

A room measured as 20 m² in square feet is 20 × 10.764 = about 215 ft². Going the other way, a 1,500 ft² apartment is 1,500 ÷ 10.764 = roughly 139 m². Notice how much larger the square-foot number always is — because a square foot is a much smaller tile than a square metre, it takes about eleven of them to cover the same ground.

Land units: acres and hectares

Bigger plots switch to acres and hectares, and these are worth memorising because they come up in property and farming:

• 1 acre = 43,560 ft² — historically the area a yoke of oxen could plough in a day.
• 1 hectare = 10,000 m² — a square 100 m on each side.
• 1 hectare = 2.471 acres, so a hectare is roughly two and a half acres.
• 1 square kilometre = 100 hectares = 247.1 acres.

Sense-checking a result

Because the squared factor trips people up, a quick gut check helps: a square-foot figure should be about eleven times its square-metre equivalent, and an acre is a bit under half a hectare. If a conversion comes out close in size to the original, you've probably used the length factor by mistake.

The area converter handles all of these at once — enter a value, pick the unit you have and the one you want, and it shows the same area in every common unit. For the length side of the same idea see metric vs imperial, and for a worked one-dimensional conversion, converting height from centimetres to feet.