Geometry Calculators

A = l×w — area, perimeter, diagonal

A = s² — area, perimeter, diagonal of a square

½bh, Heron's formula, or 2 sides + angle (SAS)

A = πr² from radius, diameter, or circumference

A = πab — area and perimeter (Ramanujan)

½(a+b)×h — two parallel sides and height

A = b×h or A = ab·sin(θ) with two sides and angle

Area and arc length of a circular sector (pie slice)

Regular polygons (3–12 sides) from side, circumradius, or apothem

V = πr²h — volume and surface area

V = (4/3)πr³ — volume and surface area

V = (1/3)πr²h — volume, slant height, surface area

V = (1/3)Bh — square & rectangular base, surface area

V = l×w×h — box volume, surface area, diagonal

Cube, box, sphere, cylinder, cone — all 3D shapes

Pythagorean theorem + angles — enter any two values

c²=a²+b²−2ab·cos(C) — SAS and SSS triangles

a/sin A = b/sin B — AAS, ASA, SSA (ambiguous case)

Perimeter of rectangles, triangles, circles, polygons

d = √((x₂−x₁)²+(y₂−y₁)²) — 2D and 3D, midpoint, slope

M = ((x₁+x₂)/2, (y₁+y₂)/2) — 2D and 3D midpoint

All 2D area formulas with derivations, reference table, and examples

SOH-CAH-TOA, unit circle, special angles 30-60-90 and 45-45-90

All 3D volume formulas with why they work and unit conversions

Two measurements of the same shape — what each means and when to use it

Flat vs solid: properties, formulas, faces, edges, vertices, Euler's formula

How sin and cos differ — graphs, identities, phase shift, and when to use each