Calculate area of any shape
Area
80.00
sq ft
Perimeter
36.00
ft
Area = length × widthCalculate the area of a rectangle by multiplying length by width. Perimeter = 2 × (length + width).
Where:
length= The longer side of the rectanglewidth= The shorter side of the rectangleArea = π × r²Calculate the area of a circle using pi times the radius squared. Circumference = 2 × π × r.
Where:
r= Radius of the circleπ= Pi, approximately 3.14159Area = (base × height) / 2Calculate the area of a triangle as half the product of base and height.
Where:
base= The base length of the triangleheight= The perpendicular height from base to opposite vertexInputs
Result
Area = length × width = 10 × 8 = 80.00. Perimeter = 2 × (10 + 8) = 36.00.
Inputs
Result
Area = π × 5² = π × 25 = 78.54. Circumference = 2 × π × 5 = 31.42.
Rectangle/square: Length × Width. Circle: π × radius². Triangle: ½ × base × height. Example: 12 ft × 15 ft room = 180 sq ft. For irregular rooms, break into rectangles and add them up.
| Shape | Formula | Example | Area |
|---|---|---|---|
| Rectangle | L × W | 12 ft × 10 ft | 120 sq ft |
| Square | side² | 10 ft × 10 ft | 100 sq ft |
| Circle | π × r² | radius 5 ft | 78.5 sq ft |
| Triangle | ½ × b × h | base 10, height 8 | 40 sq ft |
1 sq ft = 144 sq inches. 9 sq ft = 1 sq yard. 43,560 sq ft = 1 acre. 1 sq meter = 10.764 sq ft. For construction, use sq ft. For land, use acres.
| Conversion | Multiply By | Example |
|---|---|---|
| Sq ft → Sq inches | × 144 | 10 sq ft = 1,440 sq in |
| Sq ft → Sq yards | ÷ 9 | 180 sq ft = 20 sq yd |
| Sq ft → Sq meters | ÷ 10.764 | 100 sq ft = 9.29 sq m |
| Sq ft → Acres | ÷ 43,560 | 21,780 sq ft = 0.5 acre |
Break the room into rectangles and triangles. Measure each section, calculate area of each, then add together. For L-shaped rooms: measure both rectangles separately. Subtract cutouts (closets) if not flooring them.
Calculate total area, then add waste factor. Flooring: Add 10-15%. Paint: Divide by 350-400 sq ft per gallon. Sod: Add 5-10%. Always round UP to ensure you have enough material.
| Material | Coverage | Waste Factor | Example for 200 sq ft |
|---|---|---|---|
| Flooring | Per box (20-25 sq ft) | +10-15% | 9-10 boxes |
| Paint | 350-400 sq ft/gallon | +10% | 1 gallon |
| Tile | Per box varies | +10-20% | Depends on tile size |
| Sod | Per sq ft | +5-10% | 220 sq ft |
Measure room length and width in feet. Multiply to get square feet. Carpet is sold by square yard (divide by 9) or square foot. Add 10% for waste. Include closets you want carpeted.
Area = π × r² (pi times radius squared). Radius is half the diameter. Example: 10 ft diameter pool = 5 ft radius. Area = 3.14 × 5² = 3.14 × 25 = 78.5 sq ft.
| Diameter | Radius | Area | Common Use |
|---|---|---|---|
| 4 ft | 2 ft | 12.57 sq ft | Small fountain |
| 10 ft | 5 ft | 78.54 sq ft | Hot tub |
| 15 ft | 7.5 ft | 176.71 sq ft | Trampoline |
| 24 ft | 12 ft | 452.39 sq ft | Above ground pool |
Area calculations help with flooring, painting, landscaping, and construction projects. Knowing the exact square footage helps you buy the right amount of materials.
For irregular rooms, divide the space into rectangles and triangles, calculate each section separately, then add them together. Always add a waste factor (10-15%) when ordering materials.
Remember: Area is always measured in square units (sq ft, sq m, sq yd). Length is one-dimensional; area is two-dimensional.
Last Updated: Feb 12, 2026
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