Starlight Tools directory

Geometry Tools

33 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, vectors, and coordinate geometry—all private and client-side. Try our Triangle Calculator, Circle Calculator, Cube Calculator, or Vector 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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$Geometry Trigonometric triangle solver using law of sines and cosines for SAS SSS AAS ASA SSA$

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

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

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

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

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

Sphere Calculator

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

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

Pyramid Calculator

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

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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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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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Geometry Vector projection and dot cross product calculator showing 2D and 3D vector components

Vector Projection / Dot & Cross

Dot, cross (3D), projection, angle, magnitudes, components. v1.0.0

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Geometry Vector component resolver splitting vectors into components magnitude unit vector and projection

Vector Component Resolver (2D/3D)

Resolve into components, magnitude, unit vector, projection, rejection. v1.0.0

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Angle Between Two Vectors

θ in degrees/radians, cosine similarity, dot product, magnitudes. v1.0.0

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Geometry Coordinate transformations tool applying translate rotate reflect and scale to 2D points with preview

Coordinate Transformations (2D)

Translate, rotate, reflect, scale one or many points with live preview. v1.0.0

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Geometry 2D rotation matrix calculator building R theta and rotating points about any center

Rotation Matrix Calculator (2D)

Build R(θ) and rotate points about any center; radians/degrees, CW/CCW. 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, vectors, and coordinate geometry 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, Vector Calculator, and Coordinate Transformations. Use them free anytime.