Geometry Calculator
Pick a shape, enter its measurements and the calculator returns every standard result for it: area, perimeter or circumference, surface area, volume, diameter, diagonal and more. The shapes are circle, ellipse, rectangle, trapezoid, regular polygon, sphere, cylinder, cone and cuboid. You can type a unit to label the answers with square or cubic units. Everything runs in your browser.
Areas are in square units and volumes in cubic units of whatever unit you use for the measurements, and the unit box only labels the results. Formulas: circle area is pi r squared, sphere volume is 4/3 pi r cubed, cylinder volume is pi r squared h, cone volume is a third of the cylinder, and a regular polygon has area n s squared divided by 4 tan(pi/n). The ellipse perimeter is Ramanujan's close approximation, because no exact simple formula exists. The trapezoid perimeter needs the slanted side and assumes both slanted sides are equal. Everything is worked out in your browser.
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Student ToolsAbout the Geometry Calculator
Each shape has a short set of formulas. A circle of radius r has area pi r squared and circumference 2 pi r, so a radius of 5 gives an area of 78.54 and a circumference of 31.42. A sphere has volume 4/3 pi r cubed and surface area 4 pi r squared, so a radius of 3 gives a volume of 113.10. A cylinder has volume pi r squared h, a cone has a third of the matching cylinder's volume, and a cuboid has volume l x w x h with space diagonal equal to the square root of l squared plus w squared plus h squared. A regular polygon with n sides of length s has area n s squared / (4 tan(pi/n)). A trapezoid has area (a + b) / 2 x h. An ellipse has area pi a b, but its perimeter has no simple exact formula, so the calculator uses Ramanujan's close approximation. Areas come out in square units and volumes in cubic units of whatever unit you measure in, so keep all the measurements in the same unit.
How do I find the area of a circle?▾
Square the radius and multiply by pi. A circle with a radius of 5 has an area of about 78.54.
What is the volume of a sphere?▾
It is four thirds times pi times the radius cubed. A radius of 3 gives about 113.10.
How is the volume of a cone related to a cylinder?▾
A cone with the same base and height as a cylinder holds exactly one third of its volume.
Why is the ellipse perimeter approximate?▾
There is no simple exact formula for it. The calculator uses Ramanujan's approximation, which is very close for any ellipse.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.