⚡ Wire Resistance & Voltage Drop

🛡️ 100% Client‑Side — Private
AWG · mm² · Diameter · Temperature Correction · Smart Gauge
°C
Default 40°C (typical operating)
A
W V
📋 AWG Reference (click to fill)
AWGDia (mm)Area (mm²)
Wire Resistance (round trip)
0.207 Ω
Voltage Drop
2.07 V
Drop: 17.2% Load voltage: 9.93 V
Voltage drop exceeds NEC 5% recommendation. Consider larger wire.
🔍 Smart Gauge Recommendation
%
For ≤3% drop, use at least 10 AWG (or 5.26 mm²).
📐 Step‑by‑step:

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✓ Real‑time · Temperature corrected · AWG/mm²/dia · No server

📘 Wire Resistance & Voltage Drop Guide

Wire resistance depends on material, length, cross‑section, and temperature. Voltage drop occurs when current flows through a conductor. NEC recommends keeping voltage drop under 3% for branch circuits and 5% total. Use this calculator to ensure your wiring meets safety and performance standards.

❓ FAQ

Why does temperature affect resistance?

Copper's resistance increases by ~0.393% per °C above 20°C. At 40°C, resistance is ~8% higher. This calculator automatically corrects for temperature.

How do I choose the right wire gauge?

Use the "Smart Gauge Recommendation" feature. Enter your maximum acceptable voltage drop (e.g., 3%), and the tool will suggest the minimum AWG or mm².

What is the difference between AWG and mm²?

AWG (American Wire Gauge) is a logarithmic scale used in North America. mm² is the actual cross‑sectional area. The table on the left shows equivalents.

Is this calculator suitable for AC circuits?

It's primarily for DC or low‑frequency AC where skin effect is negligible. For high‑frequency AC, additional factors apply.