How To Calculate Wire Size

Introduction: Selecting the appropriate wire size is crucial for electrical installations to ensure safety and optimal performance. This article introduces a calculator designed to help you determine the required wire size in American Wire Gauge (AWG) based on the provided current and wire length.

Formula: The formula used in this calculator involves considering a voltage drop of 3%. The calculation includes multiplying the length of the wire by the current and the voltage drop factor, then dividing by 1000.

How to Use:

  1. Enter the current in Amperes.
  2. Enter the length of the wire in feet.
  3. Click the “Calculate” button to get the required wire size in AWG.

Example: If the current is 20 Amperes, and the wire length is 50 feet, the calculation would be: (2 * 50 * 20 * 0.03) / 1000 = 0.03. Therefore, the required wire size would be approximately 0.03 AWG.


  1. Q: Why is calculating wire size important? A: It ensures that the wire can handle the current without excessive voltage drop, preventing overheating and ensuring safety.
  2. Q: What is the significance of voltage drop in wire sizing? A: Voltage drop accounts for potential loss of electrical energy as current flows through the wire.
  3. Q: Can I use this calculator for DC circuits? A: Yes, the calculator is suitable for both AC and DC circuits. Ensure the correct voltage drop factor is considered.
  4. Q: Are there specific standards for wire sizing in different applications? A: Yes, industry standards and codes provide guidelines for wire sizing based on the type of installation (residential, commercial, industrial).
  5. Q: How does temperature affect wire size selection? A: Higher temperatures may require larger wire sizes to compensate for increased resistance.

Conclusion: Calculating the required wire size is a critical step in electrical design and installation. Use this calculator to estimate the appropriate wire size in American Wire Gauge (AWG) based on the provided current and wire length, ensuring safe and efficient electrical systems.

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