Geometry Calc: Area & Volume

A geometry calculator for area, volume, perimeter and surface area, with a full triangle solver. Pick a shape, type your measurements and get every property at once, with the formula it used. Works offline, no ads.

Every formula is checked by automated tests, and you can see the full step-by-step working with your numbers substituted in: area, perimeter, surface area, volume, diagonals, slant heights, angles and more.

42 SHAPES
• 2D: square, rectangle, triangle, right, equilateral and isosceles triangles, circle, semicircle, ellipse, sector and arc length, circular segment, annulus (ring), trapezoid, parallelogram, rhombus, kite, regular pentagon, hexagon, octagon and any regular polygon
• 3D: cube, rectangular prism (box), cylinder, tube (pipe), cone, frustum, sphere, hemisphere, spherical cap, ellipsoid, torus, capsule, square, rectangular, triangular, pentagonal and hexagonal pyramids, tetrahedron, triangular, pentagonal and hexagonal prisms, and the square frustum

TRIANGLE SOLVER
Solve any triangle from SSS, SAS, ASA, AAS or SSA. In the ambiguous SSA case it shows both triangles. The right triangle solver takes any two values. You get all sides and angles plus area, perimeter, heights, medians, inradius and circumradius, with the law of sines and cosines worked out.

SOLVE FOR ANY VARIABLE
Know the volume and the radius but need the height? Solve for any dimension of any shape from a known area, volume, perimeter or length. When two answers fit, you see both, and every answer is checked.

FEET, INCHES AND FRACTIONS
Enter 3' 4-5/8" directly or tap the fraction keys (1/16 to 7/8). Results also read in feet and inches to the nearest 1/16" (or 1/8 to 1/64), which helps for woodworking, construction and DIY. Metric works too: mm, cm, m and km. Conversions include cubic yards, liters, gallons, acres and hectares.

BUILT TO BE CORRECT
• The formula on screen is exactly the formula that computed your answer, and the tests enforce it
• Exact ellipse perimeter and ellipsoid surface area from elliptic integrals; Ramanujan's approximation is shown alongside and clearly marked
• Known-value, identity and scaling tests for every shape (a hemisphere is exactly half a sphere, a frustum with no top is a cone)

ALSO
• Clean labelled diagrams for every shape
• Copy or share results with the working included
• History of your calculations, saved on your phone
• Precision setting, degrees or radians, light and dark mode
• No account, no ads, no tracking, no permissions

FREE AND PRO
Every shape, every property, the triangle solver, units and conversions are free. A one-time Pro unlock adds step-by-step working, solve for any variable and unlimited history. No subscription.

Made for students, teachers, engineers, makers and anyone who needs a quick, correct area or volume.