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Free · works for any room, yard or slab

Square Footage Calculator

Area of a rectangle, circle, triangle or L-shape — in square feet, acres and square meters. Then turn it into the material you need.

Shape

Cover this area with a material

Pick a material and depth to turn square feet into cubic yards.

Gravel needed 1.78 yd³
Open the gravel calculator →

Area

144 sq ft

0.003 acres · 13.4

Material cost (est.) $53 – $116
Pouring concrete here? See slab cost →
Area 144 sq ft

How to calculate square footage

Square footage is just area measured in square feet. For a rectangular room, floor, wall or yard, multiply the length by the width in feet. If your space isn't a simple rectangle, break it into shapes — rectangles, circles and triangles — find each area, and add them together.

  • Rectangle / room / flooring: length × width.
  • Circle: π × radius² (radius is half the diameter).
  • Triangle: ½ × base × height.
  • L-shape: the full rectangle minus the missing corner.

From square feet to material

Square footage is usually step one. To order gravel, mulch, topsoil, stone or concrete you need volume — so multiply the area by a depth and convert to cubic yards. The panel above does this and hands your numbers straight to the right material calculator.

Square footage conversions

Square feetSquare yardsSquare metersAcres
100 sq ft 11.1 9.3 0.002
500 sq ft 55.6 46.5 0.011
1,000 sq ft 111.1 92.9 0.023
5,000 sq ft 555.6 464.5 0.115
43,560 sq ft 4840.0 4046.9 1.000

1 square yard = 9 sq ft · 1 acre = 43,560 sq ft · 1 sq meter ≈ 10.76 sq ft.

Prices updated January 2026 National US averages · reviewed quarterly

Volumes use standard bag yields and a 10% waste allowance; costs are national US averages that vary by region, mix and finish. See our methodology for exactly how each figure is worked out, or check the reference sources:

Turn square footage into material

Frequently asked questions

How do I calculate square footage?
For a rectangle, multiply length × width in feet. A 12×12 room is 144 square feet. For other shapes: a circle is π × radius², a triangle is ½ × base × height, and an L-shape is the full rectangle minus the cut-out. This calculator does all four.
How many square feet are in an acre?
One acre is 43,560 square feet. The calculator shows your area in acres automatically for larger measurements.
How do I convert square feet to cubic yards?
Multiply the area by the depth in feet to get cubic feet, then divide by 27. The "cover this area" panel does it for you — pick a material and depth and it returns cubic yards.
How do I measure an irregular room?
Split it into rectangles, triangles and circles, work out each area, and add them up. For an L-shaped room, use the L-shape option and enter the cut-out.