Square Footage Calculator
Square Footage Calculator works out Area and Area including waste from Measuring, Shape and Report the area in. The default figures on this page give area of 120; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
1 step
- Plan area = 12 ft x 10 ft = 120 ft^2
Its 8 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the Square Footage Calculator calculates
Calculates floor or wall area for rectangular, square, round, triangular, trapezoidal or elliptical spaces, adds a waste allowance and estimates material quantity and cost.
How to use this Square Footage Calculator
Enter Measuring, Shape, Report the area in and Length / diameter / base. Area updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Area, Area including waste and Area (square feet).
The method follows NIST Special Publication 811, Guide for the Use of the International System of Units (exact 1 ft = 0.3048 m, 1 acre = 43,560 ft2), Weisstein, Eric W. "Trapezoid", "Ellipse" and "Circle". MathWorld — A Wolfram Web Resource and Ramanujan, S. "Modular Equations and Approximations to pi" (1914) — second approximation used for the ellipse perimeter.
12 ft x 10 ft room example
With Measuring: floor, Shape: rectangle, Length / diameter / base: 12, Width / triangle height / second parallel side: 10, the calculator returns Area: 120, Perimeter: 44, Area (square metres): 11.1483648. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Area, Area including waste and Area (square feet). The inputs you can vary are Measuring, Shape, Report the area in, Length / diameter / base, Width / triangle height / second parallel side and Distance between the parallel sides.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How many sq ft is a 12x12 room?
On the figures this page opens with — length / diameter / base 12 and width / triangle height / second parallel side 10 — the area is 120. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
Can I estimate square footage using Google Maps?
Calculates floor or wall area for rectangular, square, round, triangular, trapezoidal or elliptical spaces, adds a waste allowance and estimates material quantity and cost. On the figures this page opens with — length / diameter / base 12 and width / triangle height / second parallel side 10 — the area is 120. Put your own figures in their place and the working updates beside the result.
How big is 10x10 in sq ft?
Calculates floor or wall area for rectangular, square, round, triangular, trapezoidal or elliptical spaces, adds a waste allowance and estimates material quantity and cost. Open “How this is worked out” beside the result to see each step for your own figures.
What is 12 ft by 8 ft in square feet?
Calculates floor or wall area for rectangular, square, round, triangular, trapezoidal or elliptical spaces, adds a waste allowance and estimates material quantity and cost. On this page it is computed from Measuring, Shape and Report the area in and shown as Area, Area including waste and Area (square feet).
What information do I need for the Square Footage Calculator?
You need Measuring, Shape, Report the area in, Length / diameter / base, Width / triangle height / second parallel side, Distance between the parallel sides, Wall height and Doors and windows to deduct. The page opens with default figures that give area of 120, so you can see the scale before entering your own.
What does this Square Footage Calculator show?
It shows Area, Area including waste, Area (square feet), Area (square metres), Area (square yards), Area (square inches), Area (acres) and Area (hectares), with the working and any warnings for your entries.