Geometry Calculators
159 geometry tools — areas, volumes, trigonometry, tiles and paint
📐 Results update as you type, and every page shows the formula.
Plane Shapes25
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.Missing Side from DiagonalFind the other side and the area of a rectangle from its diagonal and one side.Square Side from AreaGet the side, perimeter and diagonal of a square when you only know its area.Trapezoid Height from AreaWork back to the height when you know the area and both parallel sides.Picture Frame Mat Opening CalculatorCut-out window size from a mat board's outer size and border width.Golden Ratio CalculatorSplit a length into the golden ratio of 1 to 1.618.
Solid Volume26
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.Cylinder Height from VolumeFind the height a cylinder needs when the volume and base radius are fixed.Sphere Radius from VolumeWork back to the radius and surface area of a sphere from its volume alone.Compost Bin Volume CalculatorUsable compost volume from bin dimensions and fill level.Cone Layout Angle CalculatorThe sector angle to cut when flattening a cone.Frustum Surface Area CalculatorSurface area of a cone with the tip cut off.Barrel Volume CalculatorCapacity of a bulging barrel from its two diameters and height.
Trigonometry & Angles27
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.Angle to Slope PercentConvert an angle of incline into the percent grade used on road signs.Two Sides from Hypotenuse and AngleGet both legs of a right triangle from the hypotenuse and one acute angle.Angle Between Clock HandsFind the angle the hour and minute hands make at a given time.Point to Line DistanceShortest distance from a point to the line y = mx + b.Line Intersection CalculatorWhere two lines written as y = mx + b cross.Quadrilateral Area from CoordinatesArea and perimeter of a four-sided shape from its corner coordinates.Distance Between CoordinatesStraight-line distance on Earth between two latitude and longitude pairs.
Circles & Arcs16
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.Circle Area from DiameterGo straight from a measured diameter to the area and circumference.Annular Sector Area CalculatorArea and perimeter of a slice cut from a ring.Circle Overlap AreaOverlap of two circles from their radii and centre distance.Rolled Length CalculatorHow long a roll is when unwound, from outer and core diameter plus thickness.
Everyday Measuring65
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.Roof Pitch AngleTurn rise and run into a roof angle, a percent grade and a rafter length.Gutter & Downspout CalculatorGutter length and downspout count from the roof perimeter and area.Greenhouse Film CalculatorPlastic film area to cover an arch-style greenhouse from its width and length.Stair Handrail LengthRail length for a sloped staircase from step count, riser and tread.Pergola Rafter CountRafters needed and total lumber length from roof width and rafter spacing.Rebar Grid CalculatorRebar count for a slab from its size and bar spacing.Retaining Wall Block CountBlocks needed from wall length, height and block size.Door & Window Trim LengthCasing/trim length needed from opening size and count.Playground Surfacing CalculatorVolume and bag count for sand or rubber-chip safety surfacing from area and depth.Insulation Board CountBoards needed from the area to cover and the board size.Raised Garden Bed SoilSoil volume and bag count for a raised bed from its length, width and height.Trellis Panel CountLattice panels needed from the total run length and panel width.Herringbone Paving WasteOrder area from the paved area and a cutting-waste percentage.Pond Liner SizeLiner length and width from the pond's length, width and depth.Deck Footing CountGrid footing count from the deck's length, width and footing spacing.Shed Floor Joist CountJoist count and total lumber length from the floor width, length and joist spacing.Prefab Fence Panel Count CalculatorPanels needed from total fence length and panel width.Walkway Paver Count CalculatorPavers needed from walkway length, width, and paver size.Garden Trellis Netting CalculatorSupport netting area from trellis height, width, and row count.Horizontal Tank Volume CalculatorLiquid left in a tank lying on its side, from the depth you measure.Miter Angle CalculatorThe saw angle for joining a frame with any number of sides.Ramp Length CalculatorRamp length from the height to climb and the slope ratio.Concrete Bag CalculatorBags of premix needed from area, slab thickness and the yield per bag.Mortar Calculator for BricklayingMortar volume and bags from a brick count and the mortar each brick takes.Grout CalculatorGrout weight from tile size, joint width and depth, and grout density.Tile Adhesive CalculatorAdhesive weight and bags from the area and the spread rate per m².Wallpaper Pattern Repeat CalculatorDrops per roll once the pattern repeat is counted, and the rolls it costs.Roof Shingle CalculatorBundles and squares from the roof area and the coverage of one bundle.Laminate Flooring Pack CalculatorPacks from room size and pack coverage, plus the offcut you can reuse.Drywall Sheet CalculatorSheets from wall and ceiling area, plus joint compound and tape per metre.Plywood Sheet CalculatorSheets needed from the area and sheet size, with the leftover you will hold.Skirting Board Length CalculatorSkirting metres and lengths to buy from the perimeter minus door openings.Mulch CalculatorBags of mulch from bed area, spread depth and the litres in one bag.Paver Sand CalculatorBedding sand weight and bags from the paved area, depth and sand density.Pool Heating Time CalculatorHours and kilowatt-hours to raise a pool by a given number of degrees.Pool Pump Run Time CalculatorTurnover time and daily run hours from pool volume and pump flow rate.Grass Seed CalculatorSeed weight and bags needed from lawn area and the sowing rate per square metre.
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.