LED Strip Voltage Drop Calculator

In long LED runs, voltage drop can cause dimming and uneven lighting. I’ll show you why accurate calculations matter, how to use our interactive calculator widget, and guide you through worked examples and downloadable tools to ensure your strips shine at full brightness.

What Is Voltage Drop in LED Strip Lighting?

Voltage drop occurs when electrical current flows through the resistance of wires and LED strip traces, causing the voltage at the end of a run to be lower than at the source. In LED strips, long cable runs or undersized wire gauge amplify this effect, leading to dimmer LEDs and uneven brightness. To calculate drop, you multiply the current (I) by the total resistance (R) of the conductors over the run length (L).

How much voltage does one LED drop?

On a standard 12 V LED strip, three LEDs share a single resistor. Each LED typically has a forward voltage of ~2.2 V (red) to ~3.2 V (green/blue), averaging around 3 V per LED. The resistor drops the remaining voltage to maintain safe current levels.

Key takeaway: Voltage drop is driven by current×resistance, and understanding each LED’s forward voltage (~3 V) helps you size wiring and resistors correctly.

Voltage-Drop Calculation Formula

Calculating voltage drop helps you prevent dimming and ensures even brightness. The basic formula is:

ΔV=I×R×L\Delta V = I \times R \times L

• ΔV = voltage drop (V)
• I = current draw (A)
• R = conductor resistance (Ω per metre)
• L = one-way length of the run (m)

For LED strips drawing 2 A per metre (≈ 24 W/m at 12 V), multiply the wire’s resistance by 2 A and the length to find the total drop.

Wire Gauge Selection & Table (T1)

Selecting the correct wire gauge minimizes voltage drop. Below is a reference table for common AWG sizes, their resistance per metre, and the resulting voltage drop at 2 A per metre:

Data source: Southwire AWG resistance chart.

Table T1 provides wire resistance and expected voltage drop per metre at a 2 A load.

Using the Interactive Calculator Widget

Our interactive calculator lets you instantly compute voltage drop without manual math. Simply enter the run length (m), current draw (A), and select your wire gauge (AWG) to see the voltage loss in real time. The widget validates inputs, displays ΔV immediately, and updates as you tweak values—ideal for planning runs of any length or wattage.

If you prefer offline tools, download the PDF or Excel versions in the next section.

Instant, user-friendly widget for accurate LED strip voltage-drop calculations.

Worked Example Calculations

Scenario 1: 5 m of 12 V LED Strip at 24 W/m

• Run length: 5 m
• Current draw: 2 A/m → total 10 A
• Wire gauge: 14 AWG (0.00829 Ω/m)
• Calculation: ΔV = I × R × L = 10 A × 0.00829 Ω/m × 5 m ≈ 0.415 V
• Result: Voltage at end = 12 V – 0.415 V = 11.585 V, a 3.5 % drop—acceptable for most runs.

Scenario 2: 10 m of 24 V LED Strip at 10 W/m

• Run length: 10 m
• Current draw: 0.42 A/m → total 4.2 A
• Wire gauge: 16 AWG (0.01317 Ω/m)
• Calculation: ΔV = 4.2 A × 0.01317 Ω/m × 10 m ≈ 0.553 V
• Result: Voltage at end = 24 V – 0.553 V = 23.447 V, a 2.3 % drop—excellent for 24 V systems.

Troubleshooting Voltage Drop Issues

When voltage drop causes dimming or uneven brightness, try these solutions:

• Inject power mid-run: Feed +12 V and GND at both ends or every 3–5 m to maintain voltage levels.
• Use thicker wire: Upgrade to a lower-AWG gauge (e.g., 12 AWG instead of 16 AWG) to reduce conductor resistance.
• Shorten run lengths: Split long strips into shorter segments and power each separately.
• Parallel feeds: Wire multiple strips in parallel back to the power supply rather than chaining end to end.
• Check connections: Ensure all solder joints and connector crimps are secure; loose contacts increase resistance.
• Add decoupling capacitors: Place a 1 000 µF capacitor across + V and GND at the start of each run to smooth voltage spikes.

For detailed wiring diagrams and best practices, see our LED Strip Wiring Guide.

Key takeaway: Strategic power injection, proper wire gauge, and clean connections prevent voltage-drop issues and keep your LED strips uniformly bright.

Frequently Asked Questions

How do you calculate the voltage drop of LED strip lights?
Use the formula ΔV = I × R × L, where I is total current (amps), R is conductor resistance per metre (Ω/m), and L is run length (m). You can also enter these values into the interactive calculator or downloadable spreadsheet for instant results.

How much voltage does one LED drop?
On a typical 12 V LED strip, three diodes share a resistor. Each LED’s forward voltage is about 2.2 V (red) to 3.2 V (green/blue), averaging roughly 3 V per LED. The resistor then drops the remaining voltage to regulate current.

What wire gauge should I choose to minimize voltage drop?
Select wire gauge based on run length and current draw. For a 5 m strip at 2 A/m, 14 AWG keeps drop under 5 %. For longer runs or higher amperage, use 12 AWG or 10 AWG. Refer to the wire‐gauge table (T1) or our calculator for precise recommendations.

How can I reduce or mitigate voltage drop issues in my LED installation?
Prevent dimming by injecting power at both ends or every 3–5 m, using thicker‐gauge wire, splitting long runs into shorter segments, wiring strips in parallel, and adding a 1 000 µF capacitor at the start of each run.

Conclusion & Next Steps

Our LED Strip Voltage Drop Calculator equips you to design flawless installations—avoiding dimming, choosing the right wire gauge, and planning power injection points. Use the embedded widget above for instant results, download the PDF/Excel tools for offline planning, and watch the demo video for a guided walkthrough.

For detailed wiring diagrams, consult our LED Strip Wiring Guide; to explore compatible hardware, visit our LED Strip Accessories collection.

Key takeaway: Accurate voltage-drop calculations and proper wiring practices ensure your LED strips shine at full brightness and uniformity.