Square footage calculators
Every square footage calculator on the site: nine room and lot shapes, tile, paint and flooring material calculators, a whole-house total, and an ANSI Z765 gross living area tool.
By shape
Pick the shape that matches the space. Any floor plan that is not on this list can be split into two or three shapes that are, then added together. Each of these pages draws your measurements to scale as you type, and lets you drag the drawing to change them.
- Circle
Area = π × (Diameter ÷ 2)²
- L-Shaped Room
Area = Outer Rectangle − Notch Rectangle
- Parallelogram
Area = Base × Height
- Rectangle
Area = Width × Length
- Circle Sector
Area = π × Radius² × (Angle ÷ 360)
- Square
Area = Side × Side
- Trapezoid
Area = ((Base 1 + Base 2) ÷ 2) × Height
- Triangle
Area = ½ × Base × Height
- Triangle (Three Sides)
Area = √(s(s-a)(s-b)(s-c)), s = (a+b+c) ÷ 2
By job
- Multi-room total
Measure every room in a house and add them into one square-footage total.
- Gross living area (GLA)
Work out a listing’s GLA using the ANSI Z765 rules appraisers apply.
By material
Turn a square-footage figure into an order quantity and a budget, waste factor included.
- Carpet
Sold by the sq ft per roll.
- Drywall
Sold by the sq ft per sheet (4x8 = 32 sq ft).
- Flooring (laminate/vinyl)
Sold by the sq ft per box.
- Hardwood Flooring
Sold by the sq ft per box.
- Paint
Sold by the sq ft per gallon.
- Tile
Sold by the sq ft per box.
Which square footage calculator do you need?
All of these tools do the same underlying job — turn measurements into an area — but they differ in what they ask for and what they give you back. Choosing by the question you are trying to answer is quicker than choosing by geometry.
If you are measuring one space, start from the shape. A bedroom, a wall or a driveway is a rectangle; a round patio or an above-ground pool is a circle; a living-and-dining room that wraps a staircase is an L-shape. Every shape page carries the formula, a worked example computed by the live calculator, and the measuring questions people actually ask about that shape.
If you are measuring a whole property, the shape pages are the wrong starting point. Use the multi-room calculator to add rooms of different shapes into one running total, or the gross living area calculator when the number is going onto a listing or into an appraisal — GLA has rules about finished basements, garages and stairwell openings that a plain total ignores.
If you already know the area and are working out what to buy, go straight to the material calculators. Each one applies that material's usual waste factor, rounds up to whole boxes, sheets or gallons, and gives a budget range — because a square footage figure on its own has never told anyone how many boxes of tile to order.
And if you just want the answer for a standard room size without measuring anything, the room size lookup has 30 common dimensions worked out in advance, each drawn to scale with its material quantities alongside.