2D Geometry calculators
24 calculators Area Calculator Calculate area and perimeter for 11 shapes: rectangle, square, triangle, circle, ellipse, trapezoid, sector, rhombus, and more. Optional cost estimate included.
Open Hexagon Calculator Solve any regular hexagon from any measurement: side, area, perimeter, diagonal, apothem, or circumradius. Metric and imperial units. Step-by-step working shown.
Open Moment of Inertia Calculator Calculate the moment of inertia for 12 shapes across multiple axes. Supports metric and imperial units, hollow bodies, parallel-axis theorem, and torque output.
Open Octagon Calculator Solve a regular octagon from any known value: side, area, perimeter, any diagonal, circumradius, or apothem. Instant results plus an optional flooring cost estimate.
Open Pentagon Calculator Solve any regular pentagon from one measurement: side, area, diagonal, height, apothem or circumradius. All outputs with step-by-step work.
Open Perimeter Calculator Perimeter calculator for 10 shapes: rectangle, square, triangle (SSS/SAS/ASA), circle, ellipse, trapezoid, parallelogram, rhombus, regular polygon, and custom sides.
Open Trapezoid Calculator Solve any trapezoid from bases and height, all four sides, base angles, or reverse-solve for a missing side. Get area, perimeter, angles, diagonals, and median.
Open Area of a Rectangle Calculator Calculate the area, perimeter, and diagonal of any rectangle. Enter length and width, or reverse-solve from area, perimeter, or diagonal. Metric and imperial units.
Open Area of Crescent Calculator Calculate the area of a crescent (lune) from two circle radii and their centre distance. Shows both lune areas, the lens overlap, and a step-by-step worked example.
Open Center of Mass Calculator Calculate the center of mass for up to 6 point masses in 1D, 2D, or 3D. Shows the weighted-average formula step by step with metric and imperial units.
Open Centroid Calculator Find the centroid (geometric center) of a triangle, polygon, or set of points. Enter vertex coordinates and get the x and y centroid instantly, with step-by-step math.
Open Conic Sections Calculator Calculate every property of any conic section: eccentricity, foci, vertices, directrix, asymptotes, latus rectum and more. Covers circles, ellipses, parabolas and hyperbolas.
Open Cross-Sectional Area Calculator Calculate cross-sectional area for 10 shapes: circle, pipe, rectangle, I-beam, T-section, C-channel, L-angle, and triangle. Metric/imperial with worked steps.
Open Cycloid Calculator Calculate cycloid arc length, area, hump length, height, perimeter, parametric coordinates, and radius of curvature for any rolling radius and angle.
Open Ellipse Calculator Calculate ellipse area, perimeter, eccentricity, focal distance, and latus rectum from semi-axes or full axes. Metric and imperial, step-by-step math shown.
Open Golden Rectangle Calculator Calculate all golden rectangle dimensions from one known value: long side, short side, diagonal, area, or perimeter. Includes unit switch and step-by-step math.
Open Orthocenter Calculator Find the orthocenter of any triangle from its three vertices. Instant result with step-by-step altitude equations, triangle type, and a live diagram.
Open Polygon Calculator Calculate area, perimeter, inradius, circumradius, interior angle, exterior angle, and diagonals of any regular polygon. Solve from any known dimension.
Open Quadrilateral Calculator Calculate the area, perimeter, and diagonals of any quadrilateral: rectangle, square, parallelogram, rhombus, trapezoid, kite, or any irregular shape.
Open Segment Addition Postulate Calculator Solve for any segment length with the segment addition postulate. Supports algebraic expressions (2x+3), shows step-by-step work, and checks collinearity.
Open Segment Area Calculator Calculate the area, arc length, chord, sagitta, and perimeter of a circular segment from radius plus angle, chord, or height. Instant results with worked steps.
Open Spiral Length Calculator Calculate the length and number of turns of an Archimedean (flat) or helical (3D) spiral. Enter outer diameter, inner diameter, and thickness for instant results.
Open Square Calculator: find A, P, d Calculate the area, perimeter, diagonal and side of a square from any one known measurement. Solve from side, area, perimeter or diagonal instantly.
Open Star Shape Calculator Calculate the area, perimeter, tip angle, and spike height of any regular star polygon. Supports 5- to 12-pointed stars with metric and imperial unit switches.
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