Area & Volume Converter
m², ft², in² and L, gal(US), ft³, m³ — enter either or both.
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The engineering
Area and volume are where unit errors compound: the length factors get squared and cubed, so 'about 3.3 ft per meter' becomes 10.8 ft² per m² and 35.3 ft³ per m³ — eyeball conversions that work for length fail by an order of magnitude here. Buildings trade in ft² (US) vs m² (everywhere else), tanks and pumps in gallons vs liters, and earthwork or airflow in ft³ vs m³.
The classic mistakes: converting the length factor instead of its square (a '100 m²' apartment listed as 328 ft² instead of 1076), the US-vs-imperial gallon again (20% — enough to mis-size a chemical dosing system), and assuming a 'gallon' of anything is a mass — it isn't, and specific gravity is a separate conversation. Enter an area, a volume, or both; each converts independently.
Where this math comes from
Volume standards are older than area ones because commerce is older than surveying regulation — the US gallon is Queen Anne's 1707 wine gallon (231 cubic inches, exact to this day), while Britain's 1824 imperial gallon was rebuilt from ten pounds of water, which is why the two never agree. The litre arrived with the metric system in 1795 as the cubic decimeter, the volume of a kilogram of water.
That water link caused metrology's quietest embarrassment: in 1901 the litre was redefined as the volume of exactly 1 kg of water at maximum density, which turned out to be 1.000028 dm³ — so for 63 years a litre wasn't quite a cubic decimeter. The 12th CGPM restored the exact dm³ definition in 1964, and the 28-ppm ghost survives only in old high-precision literature. Area, meanwhile, simply squares the length story: once 1959 fixed the foot at 0.3048 m, ft² and m² were locked exactly.
- 1707Queen Anne statute231 in³ wine gallon — still the US gallon.
- 1795French RepublicLitre defined as the cubic decimeter.
- 19013rd CGPMLitre tied to 1 kg of water — off by 28 ppm.
- 196412th CGPMLitre restored to exactly 1 dm³.
See the full timeline of the math behind every calculator →
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