How to find the perimeter of a complex figure?

Measure the length of each outer side of the shape and add these values. For curved shapes (for example, an oval), special integral formulas are used, which are also available in our calculator.

What is the perimeter measured in?

Perimeter is measured in linear units: millimeters (mm), centimeters (cm), meters (m), kilometers (km). Not to be confused with area - it is measured in square units (m²).

Circle perimeter formula

P = 2 × π × r, where r is the radius and π ≈ 3.14.

Perimeter of figures

Instant calculation of perimeter and circumference

Select a shape

Enter the shape parameters on the left
to see the calculation

Perimeter:

—

Perimeter of figures

📐 Online calculation of perimeter (P) for any shapes

The perimeter is the total length of the shape's border. Our calculator allows you to instantly calculate this value for 15+ geometric shapes: from a simple square to complex polygons. The tool is useful in construction, solving school problems and landscaping.

🚀 How to use: Select a shape from the list, enter known dimensions (sides or radius) and get the result. The answer can be copied immediately.

Basic formulas and principles

If you want to calculate manually or check the solution, use these cheat sheets:

Больше по теме: Area of figures

Side/Hypotenuse📐 Pythagorean Theorem in action This calculator solves the main problem of geometry and construction: finding the unknown side of a right triangle if the other two are known. 💡 The formula is simple: c² = a² + b².

Square📏 Calculation of room area (m²) online A simple tool for calculating the square footage of walls, floors or ceilings. Helps to know exactly the scope of work before renovating or purchasing real estate.

Figures📏 Instant calculation of the volume of geometric shapes Our tool helps calculate volume (capacity) for a wide variety of objects - from simple boxes to complex tanks.

🔵 Circle (Circumference)

To calculate, you need to know the radius (r).
Formula: P = 2 × π × r
(where π ≈ 3.14)

🔺 Triangle

Sum of the lengths of all three sides.
Formula: P = a + b + c

▭ Rectangle

The sum of the length and width, multiplied by two.
Formula: P = 2 × (a + b)

⬜ Square and Diamond

These figures have all sides equal.
Formula: P = 4 × a

Where is this useful in life?

🏗 Construction and repair

To find out how much skirting board you need in a room or how long a fence to put around the area. If you need to convert meters to feet or fathoms, use our length unit converter.

🌳 Landscape design

Calculation of the length of borders for flower beds (round or rectangular) and fences for beds.

🎓 Study

Quick check of geometry homework. The calculator shows not only the answer, but also the formula by which it was obtained.

Frequently asked questions (FAQ)

❓ How to find the perimeter of a complex non-standard figure?

The method is universal: just add the lengths of all sides of the shape. If the shape is complex (for example, an L-shaped room), break it into simple rectangles, but be careful - do not count the internal boundaries, only the external ones.

❓ What is Pi (π) in the circle formula?

This is a mathematical constant equal to approximately 3.14159. It shows the ratio of the circumference of a circle to its diameter. Our calculator uses an exact value to minimize error.

❓ How to convert the result from centimeters to meters?

There are 100 centimeters in one meter. To get meters, divide your number by 100 (for example, 520 cm = 5.2 m). For other translations, use unit converter.