Converts an area between metric and US customary units using exact square-meter equivalents.
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Inputs
value (number, from_unit, required) : The area to convert
from_unit (string, required) one of: m2, ha, km2, ft2, acre, mi2 : Unit of the input value
to_unit (string, required) one of: m2, ha, km2, ft2, acre, mi2 : Unit to convert into
Outputs
result (to_unit): The converted area
Steps
Look up the exact square-meter equivalent of from_unit and of to_unit.
Convert the input to square meters: sqm = value * m2_per(from_unit).
Convert square meters to the target unit: result = sqm / m2_per(to_unit).
Round result to 6 significant figures.
Constants
m2 = 1 m2 (source: Guide for the Use of the International System of Units (SI))
ha = 10000 m2 (source: Guide for the Use of the International System of Units (SI))
km2 = 1000000 m2 (source: Guide for the Use of the International System of Units (SI))
ft2 = 0.09290304 m2 (source: Guide for the Use of the International System of Units (SI))
acre = 4046.8564224 m2 (source: Guide for the Use of the International System of Units (SI))
mi2 = 2589988.110336 m2 (source: Guide for the Use of the International System of Units (SI))
Sources
Guide for the Use of the International System of Units (SI) (National Institute of Standards and Technology, 2026-09-30T19:29:48Z) - ft2 and mi2 are exact squares of the NIST SP 811 exact length definitions; the international acre and the hectare are exact by definition.