Plane Geometry Calculators

Area, circumference, diameter and radius. Formula, variable legend, diagram and worked example included. Instant geometry result.

Area, perimeter and diagonal of rectangles. Formula, variable legend, diagram and worked example included. Instant geometry result.

Area, perimeter and diagonal of squares. Formula, variable legend, diagram and worked example included. Instant geometry result.

Solve right triangles with Pythagorean theorem. Formula, variable legend, diagram and worked example included. Instant geometry result.

Apply the Pythagorean theorem to find any side of a right triangle. Enter two sides — get the missing side with proof shown. Free.

Calculate area and perimeter of any parallelogram. Enter base, height, and side length — see area = base × height and full perimeter. Free.

Calculate area and perimeter of any rhombus. Enter diagonal lengths or side and angle — see area = d₁×d₂/2 and all measurements. Free.

Properties of regular polygons. Formula, variable legend, diagram and worked example included. Instant geometry result.

Calculate the area of an annulus (ring shape). Enter outer and inner radii — see area = π(R²−r²) with each measurement explained. Free.

Find slope between two points. See formula, step-by-step solution and all rearrangements. Instant math solver.

Find midpoint between two points. See formula, step-by-step solution and all rearrangements. Instant math solver.

Find the distance between two points in 2D space. Enter coordinates (x₁,y₁) and (x₂,y₂) — see distance, midpoint, and slope. Free.

Solve any triangle using the law of sines. Enter known sides and angles — see all missing measurements with step-by-step solution. Free.

Solve any triangle using the law of cosines. Enter known sides and angles — see the missing measurement with formula applied clearly. Free.

Calculate ellipse area, circumference, and eccentricity. Enter semi-major and semi-minor axes — see all properties with formulas. Free.

Calculate the perimeter of any ellipse. Enter semi-major and semi-minor axes — see circumference using Ramanujan's approximation. Free.

Calculate the perimeter of any polygon or curved shape. Enter dimensions — see total boundary length with formula. Free.

Calculate regular polygon properties: area, perimeter, interior angles, and apothem. Enter side count and length — see all values. Free.

Calculate the area of an annulus (ring shape). Enter outer and inner radii — see area, circumferences, and width of the ring. Free.

Calculate the volume and surface area of a spherical cap. Enter sphere radius and cap height — see volume and curved surface area. Free.

Calculate cone volume and surface area. Enter radius and height — see slant height, lateral area, and total surface area. Free.

Calculate the volume and surface area of a regular tetrahedron. Enter edge length — see volume (a³/6√2) and surface area. Free.

Calculate the diagonals, area, and perimeter of a rhombus. Enter side length and one diagonal — see the other diagonal and all properties. Free.

Solve oblique (non-right) triangles using the Law of Sines and Cosines. Enter known sides and angles — see all missing values. Free.