Voltage Drop Calculator
Calculate voltage drop across wire runs for 12V LED strips, ESP32 power supplies, and low-voltage DC systems. Prevent dimming LEDs and brownout resets.
Last updated: May 2026
Enter values to calculate voltage drop.
How to use this voltage drop calculator
Enter your system voltage (5V, 12V, or 24V), the current your device draws, the distance from power supply to load, and your wire gauge. The calculator shows how much voltage is lost in the wire and whether it's acceptable. For LED strips, more than 0.5V drop causes visible dimming. For ESP32 boards, excessive drop triggers brownout resets.
Wire gauge reference
| AWG | Diameter (mm) | Resistance (Ω/m) | Max safe current |
|---|---|---|---|
| 18 AWG | 1.0 mm | 0.021 Ω/m | ~10A |
| 20 AWG | 0.8 mm | 0.033 Ω/m | ~7A |
| 22 AWG | 0.6 mm | 0.053 Ω/m | ~5A |
| 24 AWG | 0.5 mm | 0.084 Ω/m | ~3A |
When you need this tool
Your 12V LED strip looks dim at the far end because the power supply is 10 meters away through thin wire. Or your ESP32 keeps resetting when it activates a relay because voltage sags below 3V. Or you're wiring a workshop with 24V fans and need to know if 22 AWG is thick enough for a 5-meter run at 2 amps. Check it here before you wire it wrong.