Square Footage Calculator
Add up a whole house room by room, measure a standard shape, or click out your own outline on a grid. See square feet, square meters, square yards and an optional cost.
How this square footage calculator works
Rooms: each room is length × width in feet. Rows ticked Subtract (a closet cut out of a bedroom, a stair opening) are taken off the total. Your list is saved in the share link.
Shapes: rectangle = length × width. Triangle = ½ × base × height. Circle = π × radius². Trapezoid = ½ × (side 1 + side 2) × height. An L-shape is two rectangles added together.
Draw: every corner you place has an x and y position on the grid. The area comes from the shoelace formula, which adds up (x₁·y₂ − x₂·y₁) for each pair of neighboring corners and halves the result. Perimeter is the sum of the edge lengths.
Conversions: 1 sq ft = 0.0929 sq m, and 9 sq ft = 1 sq yd.
Living area vs. total area
Living area (heated, finished space) is what real estate listings and appraisals quote. Total area also includes garages, porches, and unfinished basements or attics. They are often quite different, so know which one you are measuring. In the U.S., the common standard for measuring a single-family house is ANSI Z765. It measures from the outside face of the exterior walls, on each finished level, and counts only finished space above ground. Garages, porches and below-grade rooms are left out of that number. Measuring room by room from the inside gives a smaller figure.
Tips
- Measure walls at floor level and round to the nearest inch (use decimals: 7 ft 6 in = 7.5).
- For flooring, tile or paint, use the room-by-room inside measurements. For listings and taxes, expect the outside-wall method.
- Buy 5–10% extra material for cuts and waste.
Estimates only — not engineering, legal or code advice. Check requirements with your local building department and a licensed professional before you build.
Common questions
How do I calculate square footage of a room?
Measure the length and width in feet and multiply them. A 12 ft × 14 ft room is 168 sq ft. For a room that is not a plain rectangle, split it into rectangles, work out each one, and add them together. The Shapes tab does this for L-shapes.
How do I find the square footage of an L-shaped room?
Split the L into two rectangles that do not overlap, multiply length by width for each, and add the two answers. For example, a 15 × 10 ft rectangle plus an 8 × 6 ft rectangle is 150 + 48 = 198 sq ft.
What is the difference between living area and total square footage?
Living area (also called heated or finished area) counts only finished, heated space. Total area also counts things like garages, porches and unfinished basements. Listings and appraisals quote living area, so mark garages and porches as Not heated in the Rooms tab to see both numbers.
How do I convert square feet to square meters or square yards?
Multiply square feet by 0.0929 to get square meters, or divide by 9 to get square yards. So 1,000 sq ft is about 92.9 sq m and 111.1 sq yd.
How do I measure an odd-shaped room or floor plan?
Use the Draw tab. Click or tap each corner in order around the outline and the tool uses the shoelace formula to work out the area. You can also split the room into rectangles and triangles and add them up by hand.
How much extra flooring should I buy?
Most installers suggest adding about 5 to 10 percent to the room area for cuts and waste, and more for diagonal patterns or tile. Work out the room area here, then multiply by 1.10 before you order.