Math and Geometry Calculators and Formulas
Area calculators for every common shape, each with its formula, a worked example and results in m², ft², acres or hectares, plus length, area and volume converters.
13 calculators · 3 converters · common conversions
Math & Geometry Formulas and Calculators
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Area Calculator
A = l × w, ½bh, πr² …
Each shape has its own formula; pick the shape to see it
Example: A 40 m × 25 m plot: Area A = 1000 m².
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Area of a Rectangle Calculator
A = l × w
l length, w width
Example: An 8 m × 5 m room: Area A = 40 m².
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Area of a Triangle Calculator
A = ½ b h = √[s(s−a)(s−b)(s−c)]
b base, h height, a b c sides, s = (a+b+c)/2
Example: A triangle with sides 5, 6 and 7 cm: Area A = 14.6969 cm².
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Area of a Circle Calculator
A = π r² = π d² ÷ 4
r radius, d diameter, π ≈ 3.14159
Example: A circle with a 5 cm radius: Area A = 78.5398 cm².
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Area of a Square Calculator
A = a² = d² ÷ 2
a side length, d diagonal
Example: A square with 5 cm sides: Area A = 25 cm².
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Area of a Trapezoid Calculator
A = ½ (a + b) h
a, b parallel sides, h perpendicular height
Example: A trapezoid with parallel sides 8 cm and 5 cm and height 4 cm: Area A = 26 cm².
Show 7 more
- Area of a Parallelogram Calculator – Base and perpendicular height → parallelogram area.
- Area of a Rhombus Calculator – Two diagonals → rhombus area, side and perimeter.
- Area of a Sector Calculator – Radius plus angle (degrees or radians) or arc length → sector area and arc length.
- Area of a Semicircle Calculator – Radius or diameter → semicircle area, arc and perimeter.
- Area of an Ellipse Calculator – Semi-major and semi-minor axes → ellipse area and perimeter.
- Area of a Regular Polygon Calculator – Number of sides and side length → area of a pentagon, hexagon, octagon or any regular polygon.
- Area of a Ring (Annulus) Calculator – Outer and inner radius → ring (annulus) area, e.g. a washer or pipe wall.
Unit Converters for Math & Geometry
- Area Converter – m², cm², mm², ft², in², test areas
- Length Converter – m, km, cm, mm, µm, ft, in, mi, yd, nmi
- Volume Converter – L, mL, m³, ft³, in³, US gal, imp gal
Common Math & Geometry Conversions
Using these area calculators
Every area calculator here accepts lengths in any unit and returns the area in the unit you choose, from mm² to acres and hectares. The conversion is exact, so 1 acre is always 4046.8564224 m² and 1 ft² is 0.09290304 m².
Pick the formula that matches what you can measure. A triangle can be solved from base and height, from three sides (Heron’s formula) or from two sides and the angle between them; a circle from its radius, diameter or circumference. Irregular plots can be split into rectangles and triangles and the areas added.