Geometry Calculators
A hundred geometry tools — areas, volumes, trigonometry, tiles and paint
📐 Results update as you type, and every page shows the formula.
Plane Shapes20
Circle Area CalculatorGet the area and circumference of a circle from its radius.Radius from CircumferenceMeasure around an object and work back to radius and area.Triangle Area CalculatorFind a triangle’s area from its base and height.Heron's Formula CalculatorFind a triangle’s area from three side lengths, without knowing the height.Trapezoid Area CalculatorArea of a trapezoid from its two parallel sides and height.Parallelogram AreaArea and perimeter of a parallelogram from base, height and side.Rhombus Area CalculatorArea and side length of a rhombus from its two diagonals.Regular Polygon AreaArea of a regular polygon from side count and side length.Ellipse Area CalculatorArea and perimeter of an ellipse from its two semi-axes.Circular Sector AreaArea and arc length of a sector from radius and central angle.Square: Area, Perimeter, DiagonalOne side gives you area, perimeter and the diagonal.Rectangle DiagonalDiagonal, area and perimeter from width and height.Equilateral TriangleArea, height and both circle radii from one side.Regular Hexagon AreaArea and diagonals of a hexagon from one side.Triangle Area from Two Sides and the AngleFind the area without knowing the height.Triangle InradiusThe radius of the circle that fits snugly inside a triangle.Triangle CircumradiusThe radius of the circle through all three vertices.Regular Polygon: Both RadiiCircumradius and inradius from the side count and side length.Scale Factor to Area and VolumeHow area and volume grow when you scale length.Triangle CentroidCentroid and area from three vertex coordinates.
Solid Volume20
Cube Volume CalculatorVolume and surface area of a cube from one edge.Box Volume CalculatorVolume and internal diagonal of a rectangular box.Cylinder Volume CalculatorVolume and surface area of a cylinder from radius and height.Cone Volume CalculatorVolume and slant height of a cone from radius and height.Sphere Volume CalculatorVolume and surface area of a sphere from its radius.Hemisphere VolumeVolume of a bowl-shaped hemisphere from its radius.Pyramid Volume CalculatorVolume of a rectangular pyramid from base dimensions and height.Triangular Prism VolumeVolume from a triangular cross-section and the prism length.Pipe Material VolumeWall volume and inner capacity of a pipe from its radii and length.Torus (Donut) VolumeVolume of a torus from its centre radius and tube radius.Cube Surface AreaSurface area, volume and space diagonal from one edge.Box Surface Area & DiagonalSurface, volume and space diagonal from three edges.Cylinder Surface AreaTotal and lateral surface from radius and height.Sphere Surface AreaSurface area and volume from the radius.Cone Surface Area & SlantSlant height and surface area from radius and height.Frustum Volume (Cup Shape)Volume of a shape whose two ends differ in radius.Capsule VolumeVolume of a cylinder with hemispherical ends.Ellipsoid VolumeVolume of an egg-shaped solid with three different radii.Spherical Cap (Partly Filled Sphere)Volume in a spherical vessel filled to a given depth.Square Pyramid Surface AreaSurface and volume of a pyramid on a square base.
Trigonometry & Angles20
Pythagorean TheoremFind the hypotenuse from the two legs of a right triangle.Missing Leg of a Right TriangleFind the remaining side from the hypotenuse and one leg.Angle from Two SidesGet the angle of a slope from its rise and run.Trig Function ValuesEnter an angle and see sine, cosine and tangent at once.Slope Grade CalculatorConvert rise over run into a percentage grade and an angle.Distance Between Two PointsStraight-line distance and bearing from two coordinates.Midpoint CalculatorThe exact centre point between two coordinates.Polygon Angle CalculatorInterior angle, exterior angle and angle sum from the side count.Degrees to RadiansConvert an angle to radians and see it as a multiple of π.Law of Cosines CalculatorFind all three angles of a triangle from its three sides.Law of SinesFind the remaining sides and angle from one side and two angles.All Three Angles from Three SidesMeasure only the sides and get every angle.Height from an Angle of ElevationFind a building or tree height from distance and angle.3D Distance Between Two PointsThe straight-line distance between two points in space.Angle Between Two VectorsUse the dot product to find the angle between two directions.Bearing Between Two PointsBearing from north and distance from two coordinates.Inverse Trig (Ratio to Angle)Work back from a trigonometric ratio to the angle.Ladder Safe AngleThe lean angle from ladder length and distance from the wall.Polar to Cartesian CoordinatesTurn a radius and angle into x and y.Triangle Area from Coordinates (Shoelace)Area from three vertex coordinates alone.
Circles & Arcs12
Arc Length CalculatorLength of a circular arc from radius and central angle.Chord Length CalculatorLength of the straight line across a circle for a given angle.Radius from AreaWork back from a circle’s area to its radius and diameter.Circular Segment AreaArea of the crescent bounded by a chord and its arc.Wheel Turns to DistanceDistance travelled from wheel diameter and revolutions.Annulus (Ring) AreaArea of a ring — the outer circle minus the inner one.Sector PerimeterPerimeter and area of a sector from radius and central angle.Circular Segment from a ChordSegment area and central angle from radius and chord.Radius from Chord and SagittaRecover a circle’s radius from a chord and its bulge height.Belt Length Between Two PulleysBelt length from two pulley diameters and the centre distance.Pipe Flow RateLitres per minute from bore diameter and flow speed.How Many Small Circles Fit in a Big OneEstimate the count from the diameter ratio.
Everyday Measuring28
Room Area CalculatorFloor area of a room in square metres and Korean pyeong.Room Volume CalculatorInterior volume from length, width and ceiling height.Paint Quantity CalculatorHow much paint you need from wall area and number of coats.Tile Count CalculatorNumber of tiles needed from floor area and tile size.Wallpaper Roll CalculatorRolls needed from wall area and roll dimensions.Concrete Volume CalculatorConcrete volume and weight from area and slab thickness.Cylindrical Tank CapacityLitres held by a cylindrical tank from diameter and height.Aquarium Volume & WeightWater volume and total weight from tank dimensions.Pizza Size ComparisonCompare one large pizza against several smaller ones.TV Inches to Width & HeightActual screen dimensions in cm from a diagonal size and aspect ratio.A-Series Paper SizeMillimetre dimensions of A0 through A10 paper.Stair Step CalculatorStep count and true riser height from total rise.Pitched Roof AreaActual roof surface from footprint area and pitch.Lumber Volume CalculatorTimber volume in cubic metres from section, length and piece count.Carpet & Flooring AreaHow much to buy, room size plus a waste allowance.Fence Post CountPosts needed from the total run and the spacing.Gravel & Sand Volume and WeightVolume and tonnage from the area and layer depth.Pool & Tank Fill TimeWater volume and fill time from size and flow rate.Decking Board CountBoards and total length from deck size and board width.Curtain Fabric WidthFabric width from window width and fullness ratio.Potting Soil VolumeCompost needed from pot diameter and depth.Brick CountBricks needed from wall area and brick size.Firewood Stack VolumeStacked volume and cords from stack dimensions.Parking Space CountHow many cars fit, from lot area and area per car.Solar Panel CountPanels and installed capacity from roof area and panel size.Rainwater HarvestHow much water a roof collects from a given rainfall.Screen Pixel Density (ppi)Pixels per inch from resolution and screen size.How Many Items Fit in a BoxItem count from box and item dimensions.
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.