Use this free square footage calculator to find the area of any shape — rectangle, triangle, circle, L-shape, or irregular space. Enter your dimensions, get instant results in square feet, square yards, square meters, acres, and cubic feet. No signup, no ads, no nonsense.

How to Use This Square Footage Calculator

Select your shape, enter the dimensions in feet, and hit Calculate. For rectangular rooms and spaces, enter the length and width. For triangles, enter the base and height. For circles, enter the radius (half the diameter). For L-shaped spaces, measure each rectangle separately and the calculator adds them. For irregular shapes, break the area into sections, measure each one, and add as many rows as you need.

If you need cubic feet — for concrete, mulch, soil, or insulation — check the optional depth box, enter the thickness in inches, and the calculator will add cubic measurements to your results automatically.

How to Calculate Square Footage

Square footage is simply the area of a flat surface measured in square feet. For a rectangle or square, the formula is length × width. A room that’s 12 feet long and 10 feet wide is 120 square feet. That’s all there is to it for most spaces.

Rectangle or Square

Length (ft) × Width (ft) = Square feet. This covers the majority of rooms, lawns, driveways, patios, and outdoor spaces.

Triangle

(Base × Height) ÷ 2 = Square feet. Use this for triangular garden beds, corner lots, or any three-sided space. The height is the perpendicular distance from the base to the opposite point — not the length of a side.

Circle

π × Radius² = Square feet. The radius is half the diameter. A circular patio with a 10-foot radius has an area of about 314 square feet.

L-Shape

Split the L-shape into two rectangles. Measure each one separately, calculate the area of each, and add them together. The calculator does this automatically — just enter the dimensions of both rectangles.

Irregular Shape

Break any irregular space into a series of rectangles. Measure the length and width of each section, add them as rows in the calculator, and it totals the area for you. This works for oddly shaped yards, gardens, rooms with alcoves, or any space that doesn’t fit a standard shape.

Square Footage Conversion Chart

Here’s a quick reference for the most common conversions:

— 1 square foot = 144 square inches
— 1 square foot = 0.111 square yards
— 1 square foot = 0.0929 square meters
— 1 square yard = 9 square feet
— 1 acre = 43,560 square feet
— 1 hectare = 107,639 square feet

The calculator above runs all of these conversions automatically, so you don’t need to do the math manually.

When Do You Need Cubic Feet?

Square footage measures a flat surface. Cubic feet adds a third dimension — depth or thickness — and is what you need when you’re ordering materials that fill a volume rather than cover a surface. Common uses:

— Mulch, topsoil, or compost: coverage depends on depth, not just area
— Concrete for slabs or footings: always ordered by volume
— Gravel for a path or driveway base: measured in cubic yards
— Insulation: rated by thickness and area coverage
— Sand for a paver base or sandbox: depth determines how much you need

To get cubic feet, multiply your square footage by the depth in feet. Our calculator handles the inches-to-feet conversion automatically — just enter the depth in inches and it does the rest. If you need cubic yards instead of cubic feet, divide the cubic feet result by 27.

Common Square Footage Questions

How do I measure a room for flooring?

Measure the length and width of the room at the widest points. Multiply them together for the square footage. Add 10% for waste and cuts — more if you’re installing diagonal or patterned flooring. For L-shaped rooms, measure each rectangle separately and add them.

What’s the square footage of an acre?

One acre is exactly 43,560 square feet. A standard American football field (including end zones) is about 57,600 square feet — roughly 1.32 acres. A half-acre lot is 21,780 square feet.

How do I convert square feet to square yards?

Divide square feet by 9. A 180 square foot room is 20 square yards. Carpet is often sold by the square yard, so this conversion comes up frequently.

How do I measure an irregular lawn or yard?

Walk the perimeter and break the space into rectangles on paper. Measure each section with a tape measure or measuring wheel, calculate the area of each, and add them up. The calculator’s irregular shape mode is built exactly for this — add as many sections as your yard has.

How many square feet is a 10×10 room?

100 square feet. A 10×10 room is the size of a small bedroom or a large walk-in closet. For comparison, a typical master bedroom runs 200–300 square feet and an average American home is around 2,300 square feet.

Related Calculators

If you’re working on a specific project, these calculators pick up where the square footage number leaves off — telling you exactly how much material to buy:

Our topsoil calculator helps you convert square footage and depth into cubic yards or bags of topsoil. The mulch calculator does the same for mulch — enter your square footage and desired depth and it tells you how many bags or bulk yards to order. For hardscape projects, the gravel calculator and sand calculator handle coverage calculations for driveways, paths, and paver bases.