⚡Power & Energy
Voltage Drop Calculator
Calculate the voltage drop in copper cables for DC circuits. Essential for IoT, solar, automation, and low-voltage installations.
Formula Explanation
The voltage drop is calculated using Ohm's Law applied to the cable resistance:
Vdrop= I × R
The cable resistance (round trip) is:
R = 0.0175 × (2 × L) / A
Where:
- 0.0175— Copper resistivity (Ω⋅mm²/m)
- 2 × L— Round-trip cable length (go and return)
- A— Wire cross-sectional area (mm²)
The voltage at the load is simply the source voltage minus the drop:
Vload = Vsource − Vdrop
Reference: AWG to mm² Conversion
Common wire gauges used in IoT and low-voltage projects.
| AWG | mm² | Voltage Drop at 12V, 2A, 20m |
|---|---|---|
| AWG 24 | 0.205 mm² | 6.83 V (56.9%) |
| AWG 22 | 0.326 mm² | 4.29 V (35.8%) |
| AWG 20 | 0.518 mm² | 2.70 V (22.5%) |
| AWG 18 | 0.823 mm² | 1.70 V (14.2%) |
| AWG 16 | 1.31 mm² | 1.07 V (8.9%) |
| AWG 14 | 2.08 mm² | 0.67 V (5.6%) |