Area converter
Area converter, no network, no rounding surprises.
Runs on your device. The file is never uploaded.
Area converter rewrites a figure across hectares, acres and the squared units m2, km2, ft2 and mi2. Square metres are the base, so a hectare is 10,000 m2 and an acre 4046.8564224. It converts an area you already worked out; multiplying the sides of a shape is left to you.
Questions
Which area units are supported?
Six: m2, km2, ha, acre, ft2 and mi2, where m2 means square meters and ft2 square feet. Square meters are the base. A hectare is 10,000 m2, an acre is 4046.8564224 m2, and a square mile is 2589988.110336 m2, both taken from the exact international definitions.
How many acres are in a hectare?
Slightly under 2.47. Convert 1 ha to acre and you get the full figure, 10000 divided by 4046.8564224. Going back the other way, an acre is a little over 0.4 ha. Both directions read the same factors out of the same table, so they agree with each other exactly.
Why is there no square yard or square inch?
Because they are not in the table. The dropdowns offer m2, km2, ha, acre, ft2 and mi2, and nothing else. For a square yard, convert to ft2 and divide by nine. For square inches, take the ft2 figure and multiply by 144.
Can it work out the area of a shape for me?
No, it converts an area you already have from one unit to another. Multiply the sides yourself first and paste the number in. For a geographic footprint, the bounding-box calculator gives you the corners of a box around a set of points, though it does not compute the area of that box either.
Why did it reject my value?
The value must parse as a finite number, otherwise you get "value must be a number". Take the unit out of the box, use a dot as the decimal separator and drop any thousands separators. Large areas are fine in scientific notation, so 1.5e7 is a valid entry.
How precise is the result?
The factors are exact definitions and the arithmetic is a single multiply and divide in ordinary JavaScript numbers, so the only error is normal floating-point rounding. Nothing is rounded for display, which is why an answer can end in a long decimal tail. Trim it to whatever your survey or listing needs.