Voltage Drop Calculator
Voltage Drop Engineering
The Math
Vdrop = I × R × L × 2Where:
- I = current in Amps
- R = resistance per meter of wire (Ω/m)
- L = length in meters
- ×2 = wire runs both + and - (round trip)
Wire Resistance Reference
| AWG | Ω/m (copper) | Max amps (chassis) | Max amps (power transmission) |
|---|---|---|---|
| 22 | 0.053 | 7A | 2A |
| 20 | 0.033 | 11A | 3A |
| 18 | 0.021 | 16A | 5A |
| 16 | 0.013 | 22A | 8A |
| 14 | 0.0085 | 32A | 12A |
| 12 | 0.0052 | 41A | 17A |
| 10 | 0.0033 | 55A | 24A |
Quick Reference: Max Strip Length by Voltage
| Wire to strip | 5V (no injection) | 12V (no injection) | 24V (no injection) |
|---|---|---|---|
| 18 AWG | 2.5m | 8m | 15m |
| 16 AWG | 3m | 10m | 20m |
| 14 AWG | 4m | 12m | 25m |
Practical Rules of Thumb
- 5V strips: Inject power every 3m. Use 18 AWG minimum
- 12V strips: Inject every 8-10m. Use 18 AWG minimum
- 24V strips: Inject every 15m. Use 20 AWG minimum
- Wire thickness matters more for 5V (higher current) than 12V or 24V