CalcCommonsHow to use
Choose a geometric shape and length unit. Enter A as base, side, or radius. Enter B as perpendicular height, except for a trapezoid where B is the second parallel base and C is the perpendicular height.
For related tasks, try the Square Footage Calculator.
Formula & how it works
Rectangle/parallelogram: A = bh. Square: A = s². Triangle: A = bh/2. Circle: A = πr². Trapezoid: A = (a + b)h/2.
Worked example
Example 1
A trapezoid with bases 8 m and 12 m and height 5 m has area (8 + 12) × 5/2 = 50 m².
Assumptions & practical notes
Choose a radius for circles, not diameter. A sloping side is not the perpendicular height of a triangle or parallelogram.
This geometry tool evaluates one shape; use Square Footage for multiple rooms and price estimates.
See our calculation methodology for unit definitions and testing practices.
Results are estimates for planning purposes. Verify measurements, product specifications, and applicable building codes before purchasing materials or starting work.
Frequently asked questions
Why are conversion factors squared?
Area has two length dimensions. Since 1 ft = 0.3048 m, 1 ft² = 0.3048² m².
How can I measure an irregular area?
Divide it into simple shapes, calculate each, and add their areas without double-counting overlap.
Related calculators
Square Footage Calculator
Add room areas and quantities, convert square units, and estimate cost per square foot.
Volume Calculator
Calculate prism, cube, cylinder, sphere, and cone volumes in cubic units, liters, and US gallons.
Right Triangle Calculator
Solve a right triangle from two sides or one side and an acute angle.