Wire Size Calculator

Get this free online wire size calculator tool that helps you to select the correct guage of electrical wire. This calculator will give you a quick and simple solution to the problem. For using this calculator, you need to provide the inputs in the input fields and click on the calculate button. It is free tool anyone can use it.

Wire Size Calculator: Feeling exhausted on how to calculate wire size? Dont worry as we have provided you with the free tool that helps you to calculate size of the wire easily in fraction of seconds. All you need to do is just givng the input fields and click on the calculate button. And also we are providing you with the definition, formulas, and also steps and examples.

Define Wire Size?

Size of an electrical wire is defined as the cross sectional area it has the larger area the more current the wire can transmit with lower resistance.

For example, water flowing in a pipe. If we use a large pipe allows more water to flow at lower presure.

Formula of wire size

The formula of wire size can be calculated by using ohms law and also pouillets law.

A= [Iϱ2L​ / V ].

Formula is derived by ohms law and pouillets law.

V= IR (Ohm’s law)

R= ϱ [L / A]


V is the voltage drop

r is the resistance

I is the current

A is the cross sectional area.

L is the length of the wire.

How do you Calculate Wire Size?

Here are the simple steps to calculate the size of the wire easily without any issues. Go through the steps carefully.

  • Consider the values that are given in the problem.
  • Apply the wire size formula.
  • Substitute the values and simplify it.
  • Finally, get the answer of wire size easily.

Example of Wire Size

Question: Calculate the size of the wire in single phase if the current operating at 120 v and the voltage drop is 3% of a copper and then the length of the wire and current is 25 A and 100m at 50 degrees temperature.



V = 124v

I = 20A

L = 120m

Apply the formula,

A= [Iϱ2L​ / V ].

= [20 x 1.88 x 10-8 x 2x 100] / 124 x 0.03

= 26.494 mm2.

Therefore the size of the wire is 26.494 mm2.

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FAQs on Wire Size Calculator

1. How do you calculate wire size for 3 Phase?

To calculate the wire size for 3 phase, just multiply the result for a single phase supply by √3/2. i.e., A= 3​IϱL​ / V.

2. How do you use wire size calculator?

To use this wire size calculator, just simply give the inputs in the input fields and click on the calculate button.

3. How to calculate wire size for distance?

Wire size is directly proportional to the length of the cable distance.

4. What is the best tool to calculate the wire size?

Wire size calculator is the best tool to calculate wire size.