Which shapes does the geometry calculator support?

Square, rectangle, triangle and circle for area and perimeter, plus cube, cuboid, cylinder and sphere for volume and surface area.

How do I change the units?

Choose a unit such as mm, cm, m, km, in or ft at the top of the calculator. Areas are shown in square units and volumes in cubic units automatically.

Yes. Every shape shows its formula with your numbers substituted into it, for example Area = side squared with the computed value beside it.

Yes. The layout is responsive and everything runs in your browser, so it works on phones and tablets with no signup.

Pick a shape, enter its measurements, and get area, perimeter, surface area or volume instantly — with the formula and your numbers shown.

Unit

Choose your unit at the top (mm, cm, m, km, in or ft).
Click the tab for your shape and type its measurements into the boxes.
Results update as you type. Each result shows the formula with your numbers filled in.
Press Reset to clear every shape at once.

Square: area = side², perimeter = 4 × side
Rectangle: area = length × width, perimeter = 2 × (length + width)
Triangle: area = ½ × base × height, perimeter = base + side A + side B
Circle: area = π × radius², circumference = 2 × π × radius
Cube: volume = side³, surface area = 6 × side²
Cuboid: volume = l × w × h, surface area = 2(lw + lh + wh)
Cylinder: volume = π × radius² × height, surface area = 2π × radius × (radius + height)
Sphere: volume = &frac43; × π × radius³, surface area = 4 × π × radius²