01
Formula
Rectangle = L × W. Triangle = base × height ÷ 2. Circle = π × (diameter ÷ 2)².
Square yards = square feet ÷ 9. Acres = square feet ÷ 43,560. Pi is the full constant, not 3.14 rounded early. The displayed area is rounded to two decimals.
Apply for financingSquare footage calculator
Square footage calculator for area
This square footage calculator finds the area of a rectangle, a circle, or a triangle. Use it as a surface area calculator for a flat face, or as a lawn area calculator and lawn size calculator when the lawn is close to one of those shapes.
Square footage
180.00sq ft
Square yards20.00
Acres0.0041
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
Area is the face, not the volume.
A rectangle is length times width. A triangle is base times height divided by 2. A circle is pi times the radius squared, and the radius is half the diameter you enter. Results are square feet, square yards (divide by 9), and acres (divide by 43,560). For a room, measure the inside of the walls. For a lawn, measure the outside of the area you will cover and break an L-shape into two rectangles. This is flat area. A sloped roof is larger than its footprint. Use the roofing calculator for that.
02
Example
A 12 by 15 foot rectangle.
The area is 180.00 square feet, or 20.00 square yards, or 0.0041 acres. A 10 foot diameter circle is 78.54 square feet. A triangle with a 10 foot base and an 8 foot height is 40.00 square feet. Switch the shape to see those.
03
Tips
Add shapes. Do not average them.
An L-shaped lawn is two rectangles. A lawn size calculator result is only as good as the outline you measured. Ignore beds you will not cover, or subtract them. Surface area of a box has six faces. This page is one face at a time.
04
Equipment
Area tells you the job. Equipment does the job.
Once you know the square feet, material calculators turn it into yards of soil, sod, or gravel. A skid steer or loader for that work can be financed from $15,000 to $2 million through Dengaro.
Important questions
Know what to expect.
How do I use this as a surface area calculator?+
Enter one flat face. For several faces, calculate each and add the square feet. It is not a 3D surface-area formula for a sphere or a cylinder wall. Cylinder volume is on the volume calculator.
Can this be a lawn area calculator?+
Yes for a lawn that is roughly a rectangle, circle, or triangle. Measure in feet. For acres on a large property, the acreage calculator shows more decimal places on the acre line.
What is the difference between square feet and square yards?+
A square yard is a 3 by 3 foot square, so it holds 9 square feet. Carpet and some fabric are sold by the square yard. Divide by 9, which this result already does.
How do I measure a lawn size that is not a rectangle?+
Split it into rectangles and triangles, calculate each, and add. Subtract the house, the drive, and the beds if they are inside the outline you measured.
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