Area Calculator
Quickly find your Area of shapes with our free Area Calculator. Simple, fast, and accurate.
Shape
Area
What is an Area Calculator?
An area calculator computes the space inside two-dimensional shapes such as rectangles, triangles, circles, trapezoids, and parallelograms. Select a shape, enter the measurements, and get the area in your chosen units.
How to calculate area manually (the formula)
Each shape has its own formula: Rectangle: A = w × h. Triangle: A = ½ × b × h. Circle: A = πr2. Trapezoid: A = ½(a + b)h. Parallelogram: A = b × h.
Example calculation
Find the area of a circle with radius 5. A = π × 52 = π × 25 ≈ 78.54 square units. Find the area of a triangle with base 6 and height 4: A = ½ × 6 × 4 = 12 square units.
Common mistakes
- Using the wrong formula for the shape — Each shape has a unique area formula. Using the rectangle formula for a triangle gives incorrect results.
- Forgetting the ½ for triangles and trapezoids — Triangle and trapezoid areas require multiplying by ½ (or dividing by 2).
- Mixing units — All measurements must be in the same unit. Mixing inches and feet gives a wrong area.
Frequently asked questions
What is area?
Area is the amount of space inside a two-dimensional shape, measured in square units like in\u00b2, ft\u00b2, or m\u00b2.
How do you calculate the area of a rectangle?
Multiply width by height: A = w \u00d7 h. For a 5 by 3 rectangle, the area is 15 square units.
How do you calculate the area of a circle?
Use A = \u03c0r\u00b2, where r is the radius. Square the radius and multiply by \u03c0 (approximately 3.14159).
How do you calculate the area of a triangle?
Use A = \u00bd \u00d7 base \u00d7 height. Multiply the base by the height, then divide by 2.
What units are used for area?
Area is expressed in square units: square inches, square feet, square meters, square miles, etc., always with an exponent of 2.
How do you calculate the area of a trapezoid?
Use A = \u00bd(a + b)h, where a and b are the lengths of the parallel bases, and h is the height between them.