LED Voltage Drop Calculator

TOOLS

LED Voltage Drop Calculator

Drag the lengths. Compare wire sizes. See how much voltage reaches your LED strip.

Your setup

Enter your DC feed. The calculator picks the smallest copper wire that stays within your voltage-drop target.

Supply voltage

Match the voltage on your LED strip.

LED strip power

W/m
4.8
9.6
14.4
19.2
W/m

Use the strip’s rated power, not the PSU rating.

LED strip length

Strip length on this cable feed.

One-way cable length

Power supply to strip. Do not double it.

DC power supply
+ Red
− Black
→
One-way cable
→
Bande LED
Both wires are included automatically.

Max. voltage drop (%)

Wire temperature (°C)

LED load

72 W

Nominal current

3 A

Power supply

≥ 90 W

1 mm² · 2.32% drop

✓ Within target · 23.44 V at strip

Compare wire sizes

Lower drop means more voltage reaches the strip.

Wire size	Voltage drop	At strip input	Status

Copper DC supply cable only. Excludes losses inside the LED strip, connectors and controller. Check cable current rating separately.

Good to know

Quick answers

Common questions about choosing a supply cable for LED strip.

Which wire size should I choose?+

Start with the size marked Minimum: it is the smallest listed copper conductor that meets your voltage-drop target. A larger conductor reduces the drop further. Then check the cable’s current rating, terminal capacity and installation requirements. Meeting the voltage-drop target alone does not confirm a cable is suitable.

Is cable length one-way or round-trip?+

Enter the distance from the power supply to the LED strip, measured along the cable route. For a 5 m cable, enter 5. The calculator includes the outgoing and return conductors automatically. Strip length is a separate input; it sets the load, it is not added to the supply cable length.

Will this tell me if the end of my strip is dim?+

The result is the voltage at the start of the strip. A long LED strip can lose additional voltage through its own copper PCB. Follow the strip’s maximum run length and feed instructions. Separate feeds or power injection may be needed; calculate each supply cable using the load it carries.

What if the voltage drop is too high?+

Try a larger copper conductor, shorten the cable route or split the load into separate feeds. Each feed needs its own calculation. A higher system voltage reduces cable drop for the same rated load, but only change voltage if the strip, power supply and controller all support it. Do not raise the supply above the strip’s rated voltage.

How is the power supply rating calculated?+

Strip length × rated power gives the LED load. Divide that load by 0.8 to keep it at or below 80% of the power supply’s rating. For example, a 72 W strip needs at least 90 W at the strip’s specified voltage. Choose a suitable available rating and account for other loads and derating.

Calculation method

How it is calculated

A nominal-current estimate for one two-conductor copper DC feed.

I = P ÷ V
R = 2 × ρ(T) × L ÷ A
Voltage drop = I × R

Copper resistivity at 20°C: 0.01724 Ω·mm²/m. Temperature coefficient: 0.00393/°C. The return conductor is included via the factor 2. AWG areas use the standard geometric formula; mm² and AWG are separate size catalogs. This tool does not calculate AC wiring, copper-clad aluminum, multi-channel losses, ampacity, fuse size or brightness.