Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Length of a Spiral

Calculate the length of a spiral or the length of material contained in a roll.

Sponsored Links

spiral length

The length of a spiral can be calculated as

L = 3.14 n (D - d) / 2                  (1)


L = length of spiral (m, ft ...)

n = number of rings

D = spiral outside diameter (m, ft ...)

d = spiral inside diameter or opening (m, ft ...)

The equation can be used to calculate the length of a material of uniform thickness. Typical examples may be belts, garden hoses or ropes in a roll.

Spiral Length Calculator

n - number of rings

D - outside diameter (m, ft ..)

d - inside diameter )m, ft ..)

Example - Water Solar Heater

A solar heater is made like a coil with 20 mm pipe inside a 1 m x 1 m window frame. The coil is done like a doughnut with an outer radius of 0.5 m and an inner radius of 0.1 m due to the bending limits of the pipe. If the coil is with no space between the pipes the number of turns can therefore be calculated as   

n = (0.5 m) / (0.02 m)

  = 25

The length of the water pipe in the solar heater can be calculated as

L = 3.14 (25) ((1 m) - (0.2 m)) / 2 

  = 31.4 m

Sponsored Links

Related Topics

  • Mathematics

    Mathematical rules and laws - numbers, areas, volumes, exponents, trigonometric functions and more.

Related Documents

Sponsored Links

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about


This page can be cited as

  • The Engineering ToolBox (2021). Length of a Spiral. [online] Available at: [Accessed Day Month Year].

Modify the access date according your visit.


3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter


Sponsored Links