WeekendCalc

Square Footage Calculator

Pick a shape, enter its dimensions in any unit, and get the area in square feet, square yards, square meters and acres. Use it as the first step for any materials estimate.

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Results

Example job shown. Change the numbers to match yours.

Area
300.00 ft²
Square yards
33.33 yd²
Square meters
27.87 m²
Acres
0.0069 acres
Perimeter
70.00 ft
  • For an irregular area, split it into rectangles, triangles and circles, calculate each, and add them up.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

How this calculator works

Each shape has a simple formula. Dimensions in any unit are converted to feet first, so you can mix, for example, inches and meters.

rectangle = length × width triangle = ½ × base × height circle = π × (diameter ÷ 2)² trapezoid = ½ × (A + B) × height ellipse = π × (length ÷ 2) × (width ÷ 2)

Worked example: a 20 × 15 ft rectangle is 300 ft², which is 33.3 yd², 27.9 m² or 0.0069 acres. A 20 ft diameter circle is π × 10² = 314.2 ft².

Once you have the area, plug it into a materials calculator: choose "I already know the square footage" on the mulch, gravel, flooring or tile calculators.

Tips before you buy

  • Break complicated shapes into simple ones. An L-shaped room is two rectangles. A garden bed with a curved side is a rectangle plus a half-circle.
  • Measure twice, in the same unit, and write dimensions down as you go.
  • One acre is 43,560 ft². A square lot 209 ft on each side is about an acre.

Tools & materials for this project

Affiliate links As an Amazon Associate we earn from qualifying purchases. These links do not change what you pay.

Laser distance measurerTape measure (25 ft)Measuring wheelLong tape (100 ft)

Frequently asked questions

How do I calculate square footage?

For a rectangle, multiply length by width, in feet. For other shapes use the formulas above. For irregular areas, split into simple shapes and add them.

How many square feet are in an acre?

43,560 square feet.

How do I convert square feet to square yards?

Divide by 9. A square yard is 3 ft × 3 ft.

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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.