How this instrument works
Square metres are SI's derived unit of area — each one spans 1 m in both directions, and the metre itself has been fixed since 1983 by defining how far light travels in vacuum. Square feet have no independent definition at all. They inherit from the foot, and since the 1959 international yard and pound agreement — signed by standards bodies in the United States, United Kingdom, Canada, Australia, New Zealand and South Africa — every foot is 0.3048 m precisely. Square both sides and 1 ft² becomes 0.09290304 m², exact to every digit.
Running that backwards gives this page its factor. One divided by 0.09290304 is 1562500⁄145161, because 0.3048 is really 381⁄1250 and both numerator and denominator get squared. Written out, it repeats forever: 10.76391041670972…. Ten places is where convention stops, so 10.7639104167 is what appears in NIST tables, in surveying software, and in the expression driving this sheet. Relative error sits near one part in 100 billion — across an entire hectare, roughly one millionth of one ft².
Both units stay in daily use, often for identical objects. Residential listings quote ft² in America, India, Hong Kong and much of Canada, while Europe, Japan and Australia price by m²; Australian builders still talk in squares, each one 100 ft² or 9.290304 m². Flooring, tile, drywall and turf are sold per ft² on one side of an ocean and per m² on another, so a single renovation quote can carry both. Office leases add another wrinkle: rent per ft² per year in New York, per m² per month in Paris.
- Type your area into Square metres (m2). It opens at 100, about a two-bedroom flat.
- Read Square feet (ft2) directly beneath — every digit recomputes as you type, with no button to press.
- Working from a room's dimensions? Multiply length by width in metres first, then enter that product.
- Need ft² back to m²? Divide by 10.7639104167, or multiply by 0.09290304 — that reverse factor is exact.
Worked example — a 100 m² flat quoted in ft²
A Rotterdam listing gives a flat as 100 m², and a buyer in Houston wants that in units their own house is sold in. Leave Square metres (m2) at 100 and Square feet (ft2) returns 1076.39104167 — call it 1,076 ft², about what a two-bedroom American apartment offers.
Sanity-check it by geometry rather than arithmetic. 100 m² is a square 10 m on a side; 10 m is 32.8084 ft; 32.8084 squared is 1076.39. Same answer, reached without touching a conversion table, and it shows exactly why an area needs 3.280839895 applied twice over. One more angle on that number: at 32 ft² per 4 × 8 sheet, covering this floor takes 34 sheets of plywood.
Questions
Is 10.7639104167 exact, or rounded?
Rounded, at the tenth decimal. Its true value is a fraction, 1562500⁄145161, whose decimal form 10.76391041670972… never terminates. Reverse factor 0.09290304 m² per ft² is exact, being simply 0.3048 squared. Stopping at ten places leaves an error near one part in a hundred billion, which over a full hectare amounts to about a millionth of a ft² — far below anything a tape measure or laser distance meter can resolve.
Why doesn't multiplying by 3.28 work for an area?
Because area scales as length squared. Converting 100 m² by 3.280839895 yields 328 ft², under a third of a correct 1076 ft² answer. Any factor taking metres to feet must be applied twice for an area and three times for a volume: 3.280839895² = 10.7639104167, while 3.280839895³ = 35.3146667 handles m³ to ft³. This single slip accounts for most wildly wrong floor areas in listings and quotes.
Is an imperial square foot identical to a US customary one?
Yes. Both descend from that international foot of 0.3048 m fixed in 1959, so ft² carries one value in London and Chicago alike. An exception lingered in American land surveying: their survey foot, 1200⁄3937 m, ran about two parts per million longer. Squared, that gap doubles to four parts per million — roughly 112 ft² across a whole square mile. NIST and NOAA retired it at the end of 2022, so new work uses a single foot.
How many square feet are in an acre or a hectare?
An acre is 43,560 ft² by definition, which converts to 4046.8564224 m² exactly. A hectare is 10,000 m², so it comes to 107,639.104167 ft², or about 2.471 acres. Both land units still do real work: acres in American and British deeds, hectares in EU farm subsidy paperwork and across most cadastral records elsewhere.
How many decimals should I keep for a room measurement?
One at most, and often none. A tape read to the nearest centimetre on a 10 m wall already carries about ±0.2 m² of uncertainty in a 100 m² floor, which is ±2 ft² — so 1076.39104167 ft² is precision this page can supply and your tape cannot. Quote 1,076 ft², or 1,080 if you paced it. Keep full digits only while chaining several conversions, then round once at the end.
Do a listing's m² and ft² figures always cover the same space?
Not reliably, and no conversion can fix that. Arithmetic is settled; what counts as floor area is not. American listings usually follow ANSI Z765, measuring to exterior wall faces; Hong Kong's first-hand sales ordinance requires saleable area alongside gross floor area; RICS promotes IPMS across Europe. Balconies, stairwells and wall thickness may be in or out. Convert a number, then ask what that number includes.