Category
Geometry & Measurement calculators
Geometry questions are mostly formula questions: pick the right one, substitute carefully, keep the units straight. Mistakes usually come from choosing the wrong formula or mixing radius with diameter.
Each calculator names the formula, shows the substitution line by line, and finishes with a check or a units reminder, so you can compare it against your own working.
All geometry & measurement tools
Pythagorean Theorem Calculator
Find a missing side or test for a right angle.
Circle Calculator
Radius, diameter, circumference and area from any one.
Triangle Calculator (Three Sides)
Area, angles and type from three side lengths.
Volume & Surface Area Calculator
Cube, cuboid, cylinder, sphere and cone.
Area Calculator
Rectangle, triangle, parallelogram, trapezoid, ellipse.
What you can do here
- Find a missing side of a right triangle
- Convert between radius, diameter, circumference and area
- Get the area, angles and type of a triangle from its three sides
- Calculate volume and surface area of common solids
Learn the method first
Guides in this category teach the idea, then hand you to the matching calculator to practise.
- How to Use the Pythagorean Theorem (With Worked Examples)
- Area and Perimeter: Formulas for Common Shapes
Questions about this category
Which units should I use?
Any, as long as every length uses the same unit. Areas are then in that unit squared and volumes in that unit cubed.
How is pi handled?
Calculations use pi at full floating-point precision. The 6-decimal value in the working is for display only.