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Voltage Drop Calculator

Calculate voltage drop in wire runs for LED strips and low voltage systems

1Wire & Load Details

Total current draw of your LED strip or load in amps

Distance from power supply to load (not round trip)

Max rated current: 7A

2Voltage Drop Analysis

26.6%

Voltage Drop

Critical - LED may not function properly

Drop in Volts

3.19 V

End Voltage

8.81 V

Power Loss in Wire

15.96 W

Voltage Drop Visualization

12V8.8V-3.19V (26.6%)50 ft • 18 AWG

Voltage Drop Guidelines

< 3%Excellent for LED strips
3% - 5%Acceptable for most applications
5% - 10%Consider larger wire gauge
> 10%Increase wire size or reduce length

Why Voltage Drop Matters for LED Installations

Voltage drop occurs when electrical current flows through wire resistance. In LED installations, excessive voltage drop causes LEDs at the end of long runs to appear dimmer than those near the power supply. For LED strips, keeping voltage drop under 3% ensures consistent brightness across the entire length.

How Voltage Drop is Calculated

Vdrop = I × R × 2L

  • • Vdrop = Voltage lost in the wire (volts)
  • • I = Current flowing through the wire (amps)
  • • R = Wire resistance per unit length (ohms/ft)
  • • L = One-way wire length (multiplied by 2 for round trip)

The calculator uses standard AWG wire resistance values at 20°C. The formula accounts for the round-trip distance since current must flow to the load and back. Aluminum wire has approximately 1.6 times the resistance of copper.

Tips for Reducing Voltage Drop

  • •Use larger wire gauge (lower AWG number) for long runs - going from 18 AWG to 14 AWG cuts resistance in half
  • •Inject power at multiple points along LED strips instead of just one end
  • •Use 24V LED strips instead of 12V - same power with half the current means 1/4 the voltage drop
  • •Keep wire runs as short as possible by positioning power supplies close to the load