Designing an open air coil wound on PVC pipe with the following specs ...

Wire = 12 gauged insulated electrical wire from Lowes

- Wire Diameter = .125 including the insulation

- Turns per inch = 8

- Total Turns = 212

- Coil Diameter = 2 inches (5.08 cm)

- Coil Radius = 1 inch (2.54 cm)

- Coil Length = 26.5 inches (67.31 cm)

- Relative Permeability = 1

I get different results depending on which online calculator I use... (see 4 examples at the end of this post)

Calculator 1, 2, 3, & 5 shown below are at least between 5% & 10% the same ...

But Calculator # 4 is way different

I've also run the numbers myself using the equations offered on each site and get the same results as the sites calculator ...

Question 1: Which Calculator is most accurate

Question 2: Which Equation for an open air inductor is most accurate?

(Understanding that in practice results may differ)

Calculator links, inputs, and outputs listed below.

Thanks for any help.

-------------------------------

Calculator # 1:

All About Circuits Coil Inductance Calculator

At: https://www.allaboutcircuits.com/tools/coil-inductance-calculator/

Input:

Coil Radius = 2.54 cm

Solenoid Length = 67.31 cm

Nummber of turns = 212

Relative Permeability = 1

Output:

170.07 uH

-------------------------------

Calculator # 2:

Telsa Scientific Coil Inductance Calculator

At: https://www.teslascientific.com/products/coil-inductance-calculator/

Input:

Coil Diameter = 2 inches

Coil Length = 26.5

Number of turns 212

Output:

164.029 uH

-------------------------------

Calculator # 3:

TranslatorCafe.com Single-Layer Coil Inductance Calculator

At: https://www.translatorscafe.com/uni...tor/coil-inductance/?D=2&Du=cm&l=1&lu=cm&N=10

Input:

Coil Diameter = 2 inches

Number of turns = 212

Length of Coil = 26.5 inches

Output:

179.7369 uH

-------------------------------

Calculator # 4:

EEWeb Coil Inductance Calculator

At: https://www.eeweb.com/tools/coil-inductance/

On the right of the Inputs ... Select "Coil Inductance Calculator"

Inputs:

Number of Turns = 212

Loop Diameter = 2 inches

Wire Diameter = .125 inch (diameter of insulation surrounding 12 guage wire)

Relative Permeability = 1

Output:

0.00409 H or 4.09 mH

-------------------------------

Calculator # 5:

Rimstar.org Inductance Calculator

At: https://rimstar.org/science_electronics_projects/coil_design_inductance.htm

Input:

Relative Permeability = 1

Number of Turns = 212

Radius= 1 inch

Length = 26.5 inches

Output:

170.5218 uH