The feeder-wire calculation
For a simple DC feeder, Ohm's law gives the basic relationship:
Voltage drop (V) = Current (A) × Circuit resistance (Ω)The circuit resistance includes the outgoing conductor and the return conductor. That is why a 10-meter one-way feeder represents roughly 20 meters of conductor in the voltage-drop calculation.
Why wire size matters
Larger AWG conductors have lower resistance. For the same current and distance, moving from 18 AWG to 14 AWG can make a major difference in delivered voltage. Lower-voltage systems are especially sensitive because the same lost voltage represents a larger percentage of the supply voltage.
Why 24V usually drops less than 12V
If the load wattage is the same, doubling system voltage halves current. Since voltage drop across the feeder is proportional to current, the higher-voltage system generally loses fewer volts in the same conductor.
The strip itself also has voltage drop
A feeder calculation does not tell the whole story. Once power enters the tape, current travels through relatively thin copper traces. The first part of the strip carries current for everything downstream; farther along the strip, less current remains. This makes the strip's internal voltage-drop pattern more complicated than a single feeder calculation.
Symptoms can include:
- Lower brightness at the far end.
- RGB tape becoming warmer or redder at the end when white is commanded.
- Addressable pixels showing color errors or resets under high load.
- A project that works at low brightness but becomes unstable at full output.
What percentage should you target?
There is no universal percentage that guarantees a good LED-tape installation because different products have different operating ranges and visual sensitivity. A 3% feeder-drop target is a useful conservative planning value, but tape-internal drop and manufacturer limits still need to be considered.
Ways to reduce voltage drop
- Use a higher system voltage when the product allows it.
- Increase feeder conductor size.
- Move the power supply closer to the load.
- Use multiple home runs instead of one heavily loaded feeder.
- Inject power at additional points along the tape.
- Split a long project into independently fed sections.
Calculator note: the current beta calculator estimates feeder-wire voltage drop. The manufacturer maximum-run field and injection estimate are separate because the exact resistance of the tape's internal copper is product-specific.
Run the numbers for your project
Use the free calculator to estimate connected load, power-supply size, feeder voltage drop, power injection, controller channels, and addressable pixel groups.
Open LED Tape CalculatorRelated guides
Sources & further reading
Planning disclaimer
This guide is for project planning and education. Verify calculations against the exact tape, power supply, controller, conductor, connectors, and manufacturer instructions. Final installation must comply with applicable electrical requirements.