Perimeter Calculator

  • Isosceles Trapezoid Calculator
    Calculate the area, leg length, and perimeter of an isosceles trapezoid from its two parallel bases and height. Fast, accurate geometry tool.
  • Heptagon Calculator
    Calculate the area, perimeter, apothem and circumradius of a regular heptagon (7-sided polygon) from its side length. Fast, free and accurate.
  • Ellipse Perimeter Calculator
    Calculate the perimeter (circumference) of an ellipse from its semi-major and semi-minor axes using Ramanujan's highly accurate approximation. Free and fast.
  • Dodecagon Calculator
    Calculate the area, perimeter, apothem and circumradius of a regular dodecagon (12-sided polygon) from its side length instantly.
  • Decagon Calculator
    Calculate the area, perimeter, apothem and circumradius of a regular decagon (10-sided polygon) from its side length, with formulas and a worked example.
  • Circumference Calculator
    Calculate the circumference of a circle from its radius or diameter using C = 2πr = πd. Also returns the area, radius, and diameter instantly.
  • Perimeter of a Triangle Calculator
    Calculate the perimeter of a triangle from its three side lengths instantly. Uses P = a + b + c and also shows the semi-perimeter.
  • Star Shape Calculator
    Calculate the area, edge length and perimeter of an n-pointed star polygon from its outer radius R and inner radius r. Free, instant, and accurate.
  • Regular Polygon Calculator
    Calculate the area, perimeter, interior & exterior angles, apothem and circumradius of any regular polygon from its number of sides and side length.
  • Pentagon Calculator
    Calculate the area, perimeter, apothem, circumradius and diagonal of a regular pentagon from its side length with exact geometric formulas.
  • Octagon Calculator
    Calculate the area, perimeter, apothem, circumradius and diagonal of a regular octagon from its side length using exact geometric formulas.
  • Hexagon Calculator
    Calculate the area, perimeter, apothem and diagonal of a regular hexagon from its side length. Free, instant, with formulas and worked examples.
  • Ellipse Calculator
    Calculate the area, perimeter (Ramanujan approximation), eccentricity and focal distance of an ellipse from its semi-major and semi-minor axes.
  • Trapezoid Calculator
    Calculate the area of a trapezoid instantly from its two parallel bases (a, b) and height (h). Also returns the median. Free, fast, and accurate.
  • Stadium Calculator
    Calculate the area and perimeter of a stadium (discorectangle) shape from its radius r and straight side length a. Free geometry calculator.
  • Regular Polygon Calculator
    Calculate the area, perimeter, apothem, circumradius and angles of any regular polygon from its number of sides and side length.
  • Rhombus Calculator
    Free rhombus calculator. Enter the two diagonals to find the area, side length and perimeter instantly using area = (d₁×d₂)/2.
  • Parallelogram Calculator
    Calculate the area and perimeter of a parallelogram from its base, height, and side. Free, instant geometry calculator with formulas and examples.

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