Area Calculator
Calculate the area of rectangles, circles, triangles, and other 2D shapes instantly
Area of
square units
Formula Used
A = square units
Quick Formula Reference
A = l × w
A = s²
A = πr²
A = ½bh
A = ½(a+b)h
A = bh
A = πab
A = ½d₁d₂
A = ½r²θ
A = ¼ns²cot(π/n)
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About Area Calculator
What is an Area Calculator?
An area calculator is a mathematical tool that helps you determine the surface area of two-dimensional shapes. Whether you're working on home improvement projects, solving geometry problems, or calculating material requirements, this calculator provides instant, accurate results for a variety of shapes.
How to Use This Calculator
- Select a shape: Choose from 10 common 2D shapes (rectangle, square, circle, etc.)
- Enter measurements: Input the required dimensions for your chosen shape
- View results: Instantly see the calculated area with the formula used
- Compare shapes: Switch between shapes to compare areas with the same measurements
Supported Shapes and Formulas
Rectangle
Formula: A = length × width
Multiply the length by the width to find the rectangular area.
Square
Formula: A = side²
Square the length of one side since all sides are equal.
Circle
Formula: A = πr²
Multiply pi (≈3.14159) by the square of the radius.
Triangle
Formula: A = ½ × base × height
Multiply the base by the height and divide by 2.
Trapezoid
Formula: A = ½ × (base₁ + base₂) × height
Add both parallel bases, multiply by height, then divide by 2.
Parallelogram
Formula: A = base × height
Multiply the base by the perpendicular height.
Ellipse
Formula: A = π × a × b
Multiply pi by both semi-axes (half the width and half the height).
Rhombus
Formula: A = ½ × d₁ × d₂
Multiply the two diagonals and divide by 2.
Sector
Formula: A = ½ × r² × θ (θ in radians)
Half the square of the radius times the angle in radians.
Regular Polygon
Formula: A = ¼ × n × s² × cot(π/n)
Uses the number of sides (n) and side length (s).
Frequently Asked Questions
What units should I use?
You can use any unit of measurement (inches, feet, meters, etc.), but be consistent. The resulting area will be in square units of whatever you input.
How accurate is this calculator?
This calculator uses standard mathematical formulas and provides results accurate to 4 decimal places. For practical applications, round appropriately for your needs.
What's the difference between area and perimeter?
Area measures the space inside a 2D shape (in square units), while perimeter measures the distance around the outside edge (in linear units).
Can I calculate irregular shapes?
For irregular shapes, try breaking them into regular shapes, calculating each area separately, then adding them together.
What is a semi-axis in an ellipse?
The semi-major axis (a) is half the longest diameter, and the semi-minor axis (b) is half the shortest diameter of the ellipse.
Tip: Always double-check your measurements before calculating. Using consistent units throughout your calculation ensures accurate results.