Area Calculator
Calculate the area and square footage of any common shape — rooms, floors, gardens, plots and more — with conversions to square feet, square metres and acres.
How to use
- Pick the shape that matches your space or object.
- Choose the unit you measured in (feet, metres, inches, yards or centimetres).
- Enter the measurements and click Calculate Area.
Free online math tool. For irregular spaces, split them into rectangles and add the areas together.
What Is an Area Calculator?
An area calculator works out how much surface a two-dimensional shape covers, in square units. It sounds abstract until you are standing in a paint shop, a flooring store, or a garden centre: every one of those purchases — paint, laminate, turf, tile, gravel — is sold and priced by area. This calculator covers the seven shapes that handle almost every real job: square, rectangle, circle, triangle, trapezoid, parallelogram and ellipse. Enter the measurements in feet, metres, inches, yards or centimetres, and it returns the area in your unit plus square feet, square metres, square inches, square yards, acres and hectares.
Square Footage: The Most Common Job
Most people arrive here with one question: "What is the square footage of this room?" Square footage is simply the area of a rectangle measured in feet — length × width. A 12 ft × 10 ft bedroom is 120 sq ft. That single number drives flooring quantities, paint coverage, air-conditioner sizing and rental listings. Measure wall to wall, use the rectangle shape above with feet selected, and you have it. For an L-shaped room, split it into two rectangles, calculate each, and add them — the same trick builders use.
The Formulas Behind It
- Square: side × side (s²)
- Rectangle: length × width
- Circle: π × radius²
- Triangle: base × height ÷ 2
- Trapezoid: (a + b) ÷ 2 × height — the average of the two parallel sides, times the height
- Parallelogram: base × height (use the vertical height, not the slanted side)
- Ellipse: π × a × b, where a and b are the two semi-axes (half the width and half the length)
Converting Between Area Units
Area conversions trip people up because the conversion factor must be squared: 1 metre is 3.28084 feet, but 1 square metre is 3.28084² = 10.7639 square feet. The landmarks worth remembering: 1 sq ft = 0.0929 sq m; 1 sq yd = 9 sq ft; 1 acre = 43,560 sq ft; 1 hectare = 10,000 sq m ≈ 2.471 acres. The calculator applies all of these automatically, so a plot measured in metres can be priced in acres without a chain of error-prone hand conversions.
How do I calculate the square footage of a room?
Measure the room's length and width in feet, then multiply: square footage = length × width. A room 15 ft long and 11 ft wide is 165 sq ft. Choose "Rectangle" above, select feet, and enter the two numbers. For rooms that are not rectangular, divide the floor plan into rectangles (and triangles where needed), calculate each part, and add the results.
How many square feet are in an acre?
Exactly 43,560 square feet — a chain (66 ft) by a furlong (660 ft), from the acre's origins as the amount of land one man with one ox could plough in a day. This calculator shows acres in every result, so a 200 ft × 200 ft plot (40,000 sq ft) reads as about 0.918 acres without further maths.
What is the area of a circle if I only know the diameter?
Halve the diameter to get the radius, then apply π × r². For a circular rug 6 ft across: radius 3 ft, area = π × 9 ≈ 28.27 sq ft. Enter the radius in the Circle shape above and the calculator does the π work for you.
How do I measure an irregularly shaped garden or plot?
Break it into the shapes on this page. Sketch the plot, draw lines to divide it into rectangles, triangles and trapezoids, measure each piece, calculate each area separately, then add them together. This "divide and add" method is accurate enough for turf, gravel and fencing estimates — professionals ordering materials add 5–10% extra for cuts and wastage.