Geometry Constructor

Build shapes and watch the numbers move. Drag the corners of a 2D shape — a triangle, rectangle, circle or regular polygon — and its area, perimeter and angles update live. Or switch to 3D and rotate a cube, sphere, cylinder, cone or pyramid while sliders set its size, with surface area and volume shown as you go.

Shape

Pick a 2D shape or 3D solid — drag to reshape, and the measurements update live
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How to Use the Geometry Constructor

Pick a shape, drag it into the size you want, and read the live measurements — no numbers to type unless you want exact values.

1

Choose 2D or 3D, then a shape

Switch between 2D shapes and 3D solids, then pick a shape from the menu — triangle, circle and regular polygon in 2D; cube, sphere, cylinder, cone, pyramid and more in 3D.

2

Drag to build it

In 2D, drag the round handles — the three corners of a triangle, a corner of a rectangle, or the radius of a circle. In 3D, drag the solid to rotate it and use the sliders to set its radius, height or base.

3

Read the live measurements

The panel shows area and perimeter for 2D shapes, or surface area and volume for solids, updating as you drag — with the exact formula used shown underneath. Prefer worked steps for one number? Try the Area of a Triangle or Volume calculators.

The panel shows area and perimeter for 2D shapes, or surface area and volume for solids, updating as you drag — with the exact formula used shown underneath. Prefer worked steps for one number? Try the Fractal Generator or Volume calculators.

Frequently Asked Questions

How does the geometry constructor work?
Pick a 2D shape or a 3D solid from the menu. For 2D shapes you drag the handles on the canvas — the three corners of a triangle, a corner of a rectangle, or the radius of a circle — and the side lengths, angles, perimeter and area update as you drag. For 3D solids you rotate the shape by dragging it and set its radius, height or base with sliders, and the surface area and volume update live. Every result shows the formula it used.
Which shapes and solids are supported?
In 2D: triangle, rectangle, square, circle and any regular polygon from 3 to 12 sides. In 3D: cube, rectangular box, sphere, cylinder, cone, square pyramid and triangular prism. Each reports the measurements that matter for that shape — perimeter and area in 2D, surface area and volume in 3D, plus slant height for cones and pyramids.
How is the area of a triangle found from three points?
From the three corner coordinates, the tool uses the shoelace formula: Area = ½·|x₁(y₂ − y₃) + …|. The side lengths come from the distance formula and the angles from the law of cosines, so a right angle shows as 90° as you drag.
What surface area and volume formulas does it use?
Sphere: V = 4⁄3·πr³, SA = 4πr². Cylinder: V = πr²h, SA = 2πr(r + h). Cone: V = ⅓·πr²h, SA = πr(r + l) with slant l = √(r² + h²). Cube: V = a³, SA = 6a². Box: V = lwh, SA = 2(lw + lh + wh). Square pyramid: V = ⅓·a²h, SA = a² + 2a·l. Each solid shows its formula beside the result.
Is it free, and is my work private?
Yes to both. It runs entirely in your browser with no sign-up and no limits, and nothing you build is uploaded or stored. If you would rather type a value and read the worked steps, the step-by-step Circle Area, Surface Area and Polygon Area calculators cover the theory side.