Starlight Tools directory

Geometry Tools

43 free, browser-based tools. No account required.

Free to use
Runs in your browser
No account required

Free browser-based geometry calculators for triangles, circles, polygons, 3D solids, conics, lines, planes, and coordinate geometry—all private and client-side. Try our Triangle Calculator, Circle Calculator, Cube Calculator, or Slope Calculator.

$Geometry Interactive triangle calculator diagram solving sides angles perimeter and area$

Interactive Triangle Calculator

Solve any triangle by entering the three values you know. v1.0

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$Similar triangles calculator for scale factors corresponding sides and areas$

Similar Triangles Calculator

Find scale factors, corresponding sides, area ratios, and matching areas with worked steps. v1.0.0

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$Geometry Trigonometric triangle solver using law of sines and cosines for SAS SSS AAS ASA SSA$

Trigonometric Triangle Solver

Law of Sines/Cosines (AAS, ASA, SAS, SSS, SSA) with ambiguous-case handling. v1.0.0

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$Geometry Herons formula calculator showing triangle area semiperimeter inradius and circumradius$

Heron’s Formula Calculator

Triangle area from three sides. Also shows semiperimeter, inradius, circumradius, altitudes. v1.0.0

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$Geometry Pythagorean triples generator listing primitive triples with right triangle diagram$

Pythagorean Triples Generator

Generate primitive & scaled triples with live diagram and CSV export. v1.0.0

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$Geometry Circle calculator finding radius diameter circumference and area from any value$

Circle Calculator

Radius, diameter, circumference, area—solve from any single value. v1.0

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Equation of a Circle Calculator

Find standard and general equations from center and radius, center and point, or three points. v1.0.0

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$Geometry Circle sector calculator for area arc length radius angle chord and perimeter$

Circle Sector Calculator

Solve area, arc length, radius, angle, chord and perimeter from any two values. v1.0.0

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$Geometry Circle chord calculator for chord length sagitta central angle radius and segment area$

Circle Chord Calculator

Calculate chord length, sagitta, central angle, arc and segment area from any two values. v1.0.0

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$Geometry Annulus calculator for ring area outer and inner radii width diameters and circumferences$

Annulus Calculator

Calculate ring area, radii, width, diameters and both circumferences from any two values. v1.0.0

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$Geometry Ellipse area and perimeter calculator using Ramanujan formulas and elliptic integral$

Ellipse Area & Perimeter

Area πab; perimeter via Ramanujan I & II + high-precision elliptic integral. v1.0.0

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Conic Equation Finder

Find equations for circles, parabolas, ellipses, hyperbolas from points/foci/directrix. v1.0.0

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$Geometry Square calculator diagram solving side diagonal area perimeter and radii$

Square Calculator

Solve from side, diagonal, perimeter, area, inradius or circumradius. v1.0.0

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$Geometry Rectangle calculator solving width height diagonal perimeter and area$

Rectangle Calculator

Find width/height/diagonal/perimeter/area from any two values. v1.0.0

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$Geometry Parallelogram calculator showing base side angle height and diagonals$

Parallelogram Calculator

Area, perimeter, heights, diagonals and angles from sides plus angle or height. v1.0.0

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$Geometry Rhombus calculator showing equal sides, diagonals and an interior angle$

Rhombus Calculator

Area, perimeter, diagonals, height and angles from sides, diagonals or area. v1.0.0

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$Geometry Trapezoid calculator for general isosceles and right trapezoids with area height and perimeter$

Trapezoid Calculator

General, isosceles, right cases. From bases/legs/height/area/perimeter. v1.0.0

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$Geometry Regular polygon calculator for n sided shapes area perimeter apothem and circumradius$

Regular Polygon Calculator

Area, perimeter, side, apothem, circumradius, angles for n-gons. v1.0.0

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$Geometry Irregular polygon area calculator using shoelace formula with centroid and orientation$

Irregular Polygon Area

Shoelace area, perimeter, centroid, orientation; CSV import; self-intersection warnings. v1.0.0

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$Geometry polygon centroid calculator showing a concave coordinate polygon and its area centroid$

Polygon Centroid Calculator

Area-weighted centroid from ordered x,y coordinates with boundary validation and formula sums. v1.0.0

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$Geometry Polygon interior and exterior angles calculator showing sum and per vertex values$

Polygon Angles Calculator

Sum & per-vertex interior/exterior angles from n or coordinates. v1.0.0

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Surface Area Calculator

Calculate total, lateral, and base area for common 3D shapes with formulas and unit-aware results. v1.0.0

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$Geometry Cube calculator diagram computing edge length surface area volume and space diagonal$

Cube Calculator

Edge, surface area, volume, space diagonal from any one value. v1.0.0

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$Geometry rectangular prism calculator for volume surface area space diagonal and face diagonals$

Rectangular Prism Calculator

Volume, surface areas, diagonals and edge length from length, width and height. v1.0.0

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$Geometry triangular prism calculator for volume surface area and prism length$

Triangular Prism Calculator

Volume, surface area and prism length from the three triangular base sides. v1.0.0

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$Geometry Cylinder calculator for radius diameter height surface area lateral area and volume$

Cylinder Calculator

Radius/diameter, height, surface, lateral area, volume from any two. v1.0.0

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$Geometry Cone calculator showing height radius slant height surface area and volume outputs$

Cone Calculator

Height, radius/diameter, slant height, surface, lateral, volume from any two. v1.0.0

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$Conical frustum calculator for volume surface area and slant height$

Conical Frustum Calculator

Volume, total and lateral surface area, slant height and base areas from two radii and height. v1.0.0

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$Geometry Sphere calculator diagram for surface area and volume from radius or diameter$

Sphere Calculator

Surface area & volume from radius/diameter. v1.0.0

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$Torus calculator for volume surface area major and minor radii$

Torus Calculator

Volume, surface area, radii and diameters from major/minor or outer/inner measurements. v1.0.0

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$Geometry Pyramid calculator for regular bases surface area volume height and slant height$

Pyramid Calculator

Surface area, volume, height, slant height for regular pyramids. v1.0.0

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$Regular tetrahedron calculator for volume surface area height edge length and radii$

Tetrahedron Calculator

Volume, surface area, height, edge length and radii from any one regular-tetrahedron measurement. v1.0.0

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2D Distance Calculator

Distance between (x₁,y₁) and (x₂,y₂). v1.0

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3D Distance Calculator

Straight-line distance between two 3D points. v1.0

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Geometry Midpoint calculator plotting the midpoint between two 2D or 3D coordinates

Midpoint Calculator (2D & 3D)

Midpoint between two coordinates; instant visual preview. v1.0.0

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Perpendicular Bisector Calculator

Find the midpoint and exact perpendicular-bisector equation from two points, with steps and graph. v1.0.0

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Parallel and perpendicular line calculator graph with two parallel lines and a perpendicular through a point

Parallel & Perpendicular Line Calculator

Find both line equations through a point from a slope, standard equation, or two points, with exact steps and graph. v1.0.0

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Slope Calculator

Slope m, angle, line equations through two points; vertical detection. v1.0.0

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Line Intersection Calculator

Intersection of two lines in Ax+By=C or y=mx+b; parallel/coincident detection. v1.0.0

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Geometry Point to line distance calculator showing perpendicular distance from point to line in 2D

Point to Line Distance (2D)

Perpendicular distance from (x₀,y₀) to a line; multiple forms supported. v1.0.0

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Geometry Point to plane distance calculator in 3D showing perpendicular foot and signed distance

Point to Plane Distance (3D)

Compute the perpendicular distance from (x₀,y₀,z₀) to a plane (Ax+By+Cz+D=0, point+normal, or three points). Shows foot of perpendicular and signed/unsigned options. Private, client-side. v1.0.0

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Geometry Plane from three points calculator deriving plane equation and unit normal vector

Plane from 3 Points

Enter three non-collinear points or a point + normal to get Ax+By+Cz+D=0. Includes unit-normal and point–normal forms, plus a friendly 3D viz. Private, client-side. v1.0.0

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Golden Ratio Calculator

Split any length into golden sections with a live diagram. v1.0.0

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About These Geometry Calculators

These geometry tools solve triangles, circles, polygons, 3D solids, conics, lines, planes, and coordinate problems entirely in your browser—no uploads or sign-ups—so homework, teaching, and quick checks stay private.

Popular picks include the Triangle Calculator, Circle Calculator, Cube Calculator, Slope Calculator, and Plane Equation Calculator. Use them free anytime.