Perimeter Calculator

  • Circle Perimeter from Diameter Calculator
    Calculate the perimeter (circumference) of a circle from its diameter using C = πd. Instantly get circumference, radius, and area for any diameter.
  • Semicircle Perimeter Calculator
    Calculate the perimeter of a semicircle from its radius using P = πr + 2r = r(π + 2). Free, instant, and shows the arc and diameter parts.
  • Equilateral Triangle Perimeter Calculator
    Calculate the perimeter of an equilateral triangle instantly using P = 3a. Enter the side length to get the total perimeter in one click.
  • Perimeter of a Rectangle Calculator
    Calculate the perimeter of a rectangle instantly using P = 2(l + w). Enter length and width to get perimeter, area, and diagonal.
  • Circle Circumference from Area Calculator
    Find the circumference of a circle from its area instantly. Enter the area and get the circumference, radius, and diameter using C = 2√(πA).
  • Diameter from Circumference Calculator
    Find the diameter of a circle from its circumference using d = C / π. Instantly calculate diameter and radius from any circumference value.
  • Radius from Circumference Calculator
    Find the radius of a circle from its circumference using r = C / (2π). Also returns diameter and area instantly in the same unit.
  • Perimeter of a Square from Area Calculator
    Find the perimeter of a square from its area instantly. Enter the area and get the side length and perimeter using P = 4√A. Free, fast, accurate.
  • Room Perimeter Calculator for Baseboard & Trim
    Calculate the perimeter of a rectangular room and the linear feet of baseboard or trim you need, minus doorways and plus a waste allowance.
  • Perimeter of an L-Shape Calculator
    Calculate the perimeter of an L-shaped figure from its overall outer width and height using P = 2 × (a + b). Fast, free, and accurate.
  • Circumference of a Circle Calculator
    Calculate the circumference of a circle from radius or diameter using C = 2πr = πd. Get circumference, diameter, and area instantly with worked examples.
  • Circumference from Radius Calculator
    Calculate the circumference of a circle from its radius using C = 2πr. Instantly get circumference, diameter, and area from any radius value.
  • Missing Side of a Rectangle from Perimeter Calculator
    Find the unknown side of a rectangle from its perimeter and one known side. Uses missing_side = P/2 − known_side. Instant, free, and accurate.
  • Arc Length from Degrees Calculator
    Calculate the arc length of a circle from its radius and central angle in degrees. Also shows radians and full circumference instantly.
  • Right Triangle Perimeter from Two Legs Calculator
    Find the perimeter of a right triangle from its two legs. Enter leg a and leg b to get the hypotenuse and total perimeter instantly.
  • Pentagon Perimeter Calculator
    Calculate the perimeter of a regular pentagon instantly using P = 5s. Enter one side length and get the total perimeter in any unit.
  • Rhombus Perimeter Calculator
    Calculate the perimeter of a rhombus instantly with P = 4a. Enter the side length and get the total perimeter in any unit. Free and accurate.
  • Square Side from Perimeter Calculator
    Find the side length of a square from its perimeter using s = P/4. Also returns the square's area and diagonal instantly.
  • Hexagon Perimeter Calculator
    Calculate the perimeter of a regular hexagon instantly using P = 6s. Enter one side length and get the total perimeter with the formula explained.
  • Arc Length from Radius and Radians Calculator
    Calculate arc length from a circle's radius and central angle in radians using s = r × θ. Free, instant, with chord length too.
  • Triangle Perimeter & Semiperimeter Calculator
    Calculate the perimeter and semiperimeter of a triangle from its three sides, with a Heron's formula area check and triangle inequality validation.
  • Square Perimeter from Area Calculator
    Find the perimeter of a square from its area using P = 4√A. Enter the area to instantly get the side length and perimeter. Free and accurate.
  • Perimeter of a Circle Calculator
    Calculate the perimeter (circumference) of a circle from its radius using P = 2πr. Also shows diameter and area. Fast, free and accurate.
  • Perimeter of a Pentagon Calculator
    Calculate the perimeter of a regular pentagon instantly with P = 5s. Enter one side length and get the total distance around all five sides.

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