Area Calculator
Calculate the area of circles, rectangles, triangles, trapezoids, and other geometric shapes.
About Area Calculator
An area calculator computes the area of common geometric shapes including circles, rectangles, triangles, trapezoids, parallelograms, ellipses, and regular polygons. Area is a fundamental measurement in geometry used in construction, landscaping, interior design, agriculture, and art. Knowing how to calculate area helps you determine how much paint, flooring, tile, or fabric you need for a project.
How to Use
Select the shape from the menu and enter the required dimensions (length, width, radius, height, base, etc.). The calculator instantly displays the area in square units. For complex shapes, it may also show intermediate calculations like the semi-perimeter of a triangle or the sum of parallel sides of a trapezoid.
Formula / Key Equations
Rectangle: A = length × width. Circle: A = pi × r squared. Triangle: A = (base × height) / 2. Trapezoid: A = ((base1 + base2) × height) / 2. Parallelogram: A = base × height. Ellipse: A = pi × a × b. Regular polygon: A = (n × s^2) / (4 × tan(pi/n)), where n = number of sides, s = side length.
Common Use Cases
Estimating paint, wallpaper, or flooring needed for a room. Calculating land area for real estate or agriculture. Planning garden beds and landscaping projects. Determining fabric requirements for sewing and upholstery. Computing surface areas for material purchasing. Solving geometry homework and exam problems.
Limitations
The calculator assumes perfect geometric shapes — real-world measurements may have irregularities. For irregular shapes, you can break them into simpler shapes and add the areas together. It does not handle 3D surface area (see our Volume Calculator for solid shapes). Results depend on the accuracy of your measurements.
Frequently Asked Questions
How do I calculate the area of an irregular shape?
Break the irregular shape into simpler shapes (rectangles, triangles, circles) that you can measure individually. Calculate the area of each simple shape and add them together. For highly irregular shapes, you can use the grid method (counting squares on graph paper) or digital tools with GPS mapping.
What is the difference between area and perimeter?
Area measures the two-dimensional space inside a shape (in square units: sq ft, sq m). Perimeter measures the total distance around the outside edge (in linear units: ft, m). They measure different things and use different formulas.
How do I calculate square footage of a room?
Measure the length and width of the room in feet, then multiply: Area = Length × Width. For an L-shaped room, divide it into two rectangles, calculate each area separately, and add them together. Include closets and alcoves if they are part of the floor area.
What is pi and why is it used in area calculations?
Pi (approximately 3.14159) is the ratio of a circle's circumference to its diameter. It appears in area formulas for any shape involving circles or curves (circles, ellipses, cylinders, spheres). It is an irrational number that continues infinitely without repeating.
Does this calculator work for 3D shapes?
This calculator computes 2D area (flat surfaces). For 3D shapes like cubes, spheres, and cylinders, use our Volume Calculator to find the space inside the shape, or calculate surface area separately (total area of all faces).
Related Tools
Scientific Calculator
Full-featured scientific calculator with trigonome...
Fraction Calculator
Add, subtract, multiply, and divide fractions. Sim...
Square Root Calculator
Calculate square roots, cube roots, and nth roots ...
Standard Deviation Calculator
Calculate mean, median, mode, standard deviation, ...
Probability Calculator
Calculate probabilities for single and multiple ev...
Exponent Calculator
Calculate powers and exponents. Supports fractiona...