Area Calculator
Calculate the area of the most common 2D shapes in one place. Choose the shape, enter the dimensions, pick the unit, and get the area with formula steps.
Area formulas used
Below are the formulas the calculator uses depending on the chosen shape.
1. Rectangle / Square
Formula: \( A = w \times h \)
Where: \( w \) = width, \( h \) = height
2. Triangle
Formula: \( A = \frac{b \times h}{2} \)
Where: \( b \) = base, \( h \) = height
3. Circle
Formula: \( A = \pi r^2 \)
Where: \( r \) = radius
4. Trapezoid
Formula: \( A = \frac{(a + b) \times h}{2} \)
Where: \( a \) and \( b \) are the parallel sides, \( h \) is the height.
5. Parallelogram
Formula: \( A = b \times h \)
Where: \( b \) = base, \( h \) = perpendicular height
6. Ellipse
Formula: \( A = \pi a b \)
Where: \( a \) = semi-major axis, \( b \) = semi-minor axis
7. Circular sector
Formula: \( A = \pi r^2 \times \frac{\theta}{360^\circ} \)
Where: \( r \) = radius, \( \theta \) = central angle in degrees
How to calculate area (step-by-step)
Step 1: Identify the shape you are working with.
Step 2: Measure the required dimensions (sides, base, height, radius...). Always keep them in the same unit.
Step 3: Plug the numbers into the correct formula above.
Step 4: Express the result in squared units, e.g. m², cm², in², ft².
This tool automates all those steps for you and also presents the structure of the formula for transparency.
Area Calculator – FAQ
Formula (LaTeX) + variables + units
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1. Rectangle / Square Formula: \( A = w \times h \) Where: \( w \) = width, \( h \) = height
2. Triangle Formula: \( A = \frac{b \times h}{2} \) Where: \( b \) = base, \( h \) = height
3. Circle Formula: \( A = \pi r^2 \) Where: \( r \) = radius
4. Trapezoid Formula: \( A = \frac{(a + b) \times h}{2} \) Where: \( a \) and \( b \) are the parallel sides, \( h \) is the height.
5. Parallelogram Formula: \( A = b \times h \) Where: \( b \) = base, \( h \) = perpendicular height
6. Ellipse Formula: \( A = \pi a b \) Where: \( a \) = semi-major axis, \( b \) = semi-minor axis
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - FTC — Consumer advice — consumer.ftc.gov · Accessed 2026-01-19
https://consumer.ftc.gov/
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.