How to Use a Wire Size Calculator for Safe Electrical Wiring
The Wire Calculator helps you choose the right wire gauge, length, and check voltage drop for any electrical project. It’s ideal for ensuring safe, efficient wiring in homes, vehicles, or DIY electronics.
How to Use the Wire Calculator
Enter:
- Voltage (V)
- Current (A)
- Wire length (ft or meters)
- Acceptable voltage drop (%)
The calculator suggests a suitable wire size (AWG) and estimates voltage drop.
Wire Size and Voltage Drop Formula
Voltage Drop: VD = (2 × Length × Current × Resistance) ÷ 1,000
Wire resistance depends on the gauge and material (usually copper or aluminum).
Example
Voltage: 120 V
Current: 15 A
Length: 100 ft
Acceptable Voltage Drop: 3%
Required Wire Size: ~10 AWG to stay within safe limits.
Common Use Cases
- Home electrical wiring
- Solar panel installations
- Automotive wiring
- RV or boat electrical systems
- DIY electronics or repairs
Why Use a Wire Calculator?
Choosing the correct wire size prevents overheating, power loss, and fire hazards — keeping your electrical systems efficient and safe.
Frequently Asked Questions (FAQs)
What is voltage drop?
Voltage drop is the loss of voltage as electricity flows through the wire due to resistance.
How much voltage drop is acceptable?
Most guidelines recommend less than 3% for branch circuits.
Does wire material matter?
Yes — copper is more conductive than aluminum and allows smaller wire sizes for the same load.
Can I use this for DC wiring?
Yes — it works for AC and DC systems like vehicles and solar setups.
Is this code compliant?
Always check local electrical codes to ensure your wiring meets safety standards.
Related tools: Voltage Calculator, Wattage Calculator.