Area Calculator
Direct answer: Area measures a flat surface in square units. Rectangle: length × width. Circle: π × radius². Triangle: (base × height) ÷ 2. For example, a 12 × 10 ft rectangle covers 120 square feet, which is 13.33 square yards or 11.15 square meters.
Area: 120.00 square feet
120.00 square feet · 13.33 square yards · 11.15 square meters · 0.00275 acres
How the calculation works
Step 1: Pick the shape, choose the input unit (feet, inches, yards, meters or centimeters), and enter its imensions. Step 2: Apply the shape’s formula — rectangle: length × width; square: side × side; circle: π × radius²; triangle: base × height ÷ 2; parallelogram: base × height; trapezoid: (base 1 + base 2) ÷ 2 × height; ellipse: π × axis 1 × axis 2. Step 3: Convert the result<: square yards = square feet ÷ 9; square meters = square feet × 0.092903; acres = square feet ÷ 43,560.
Area formulas by shape
| Shape | Formula | Example |
|---|---|---|
| Rectangle | Length × Width | 12 × 10 = 120 sq ft |
| Square | Side × Side | 15 × 15 = 225 sq ft |
| Circle | π × Radius² | π × 5² = 78.54 sq ft |
| Triangle | (Base × Height) ÷ 2 | (10 × 6) ÷ 2 = 30 sq ft |
| Parallelogram | Base × Height | 10 × 6 = 60 sq ft |
| Trapezoid | ((Base 1 + Base 2) ÷ 2) × Height | ((8 + 12) ÷ 2) × 5 = 50 sq ft |
| Ellipse | π × Axis 1 × Axis 2 | π × 6 × 4 = 75.40 sq ft |
Try the new shapes above: choose parallelogram, trapezoid or ellipse, pick an input unit — feet, inches, yards, meters or centimeters — and the calculator converts the result for you.
Area unit conversions
1 square yard = 9 square feet. 1 acre = 43,560 square feet. 1 square meter = 10.7639 square feet. 1 square foot = 0.092903 square meters. For land, acres are the usual unit; for rooms and flooring, square feet and square yards are the usual units.
Worked examples
Example 1 (rectangle): 12 ft × 10 ft = 120 square feet = 120 ÷ 9 = 13.33 square yards = 120 × 0.092903 = 11.15 square meters.
Example 2 (circle): Radius 5 ft. Area = π × 5² = 78.54 square feet.
Example 3 (triangle): Base 10 ft, height 6 ft. Area = (10 × 6) ÷ 2 = 30 square feet.
Example 4 (square): Side 15 ft. Area = 15 × 15 = 225 square feet = 25 square yards = 0.00517 acres.
Measuring irregular areas
For an irregular room or plot, split it into rectangles and triangles, calculate each part, and add the results. A common mistake is mixing units — keep every dimension in the same unit before multiplying When the space also has depth — for example, a room you plan to fill or a slab you plan to pour — the Volume Calculator takes the calculation into three dimensions. Measure twice before ordering flooring or paint: a small measuring error multiplied across a large area becomes an expensive one.
FAQs
How do you calculate the area of a rectangle?
Multiply length × width, both in the same unit.
How do you calculate the area of a circle?
π × radius². Measure the radius (half the diameter), not the diameter itself.
How do you calculate the area of a triangle?
(Base × height) ÷ 2, where height is measured perpendicular to the base.
How do you convert square feet to square yards?
Divide square feet by 9.
How many square feet are in an acre?
43,560 square feet.
How do you measure an irregular-shaped area?
Split it into rectangles and triangles, calculate each part separately, and add the results.
Related calculators: Scientific Calculator · Percentage Calculator · Volume Calculator
Last updated: November 1, 2026.