How Many LED Strip Lights Can You Run on One Power Supply? (With Simple Calculations)

You can run as many LED strip lights as you like from one power supply as long as the total strip power stays within a safe fraction of the power supply rating and the voltage matches. The simplest way to check this is to calculate the total watts of all your strips and keep that total below about 80–90% of the power supply’s rated wattage.

Understand LED strip power and power supplies in plain language

Before you worry about “how many strips”, it helps to understand a few basic power terms used on LED strip datasheets and power supplies.

• • Watts per metre (W/m) – how much power the strip uses for each metre (or per foot in imperial specs).
  • Strip length – how many metres (or feet) of strip you are installing per run.
  • Strip voltage – the DC voltage the strip is designed for (typically 5V, 12V or 24V).
  • Power supply / LED driver rating – the output voltage and maximum wattage or current that the supply can deliver safely.

For a single LED strip:

• • The strip power is simply:

strip_watts = watts_per_metre × strip_length

For multiple strips:

• • You can think in terms of either total length or per-strip wattage:

– Many datasheets give both W/m and total watts for standard lengths (e.g. a 5 m reel).

The power supply’s job is to provide stable DC voltage at the required level with enough power capacity. As long as:

1. 1. The strip voltage matches the power supply voltage, and
   2. The total strip power stays within a safe range of the supply’s rating,

you can supply one or many strips from a single power supply.

How to size a power supply for a single LED strip (using W/m and length)

Step-by-step single-strip sizing example

A good way to think about sizing is: calculate what the strip needs, then add a margin so the power supply is not working at 100% all the time.

For a single strip:

1. 1. Find W/m and length.

– Example: a 12V strip rated at 9.6 W/m and you plan to use 5 m.

1. 1. Calculate strip power.

– strip_watts = 9.6 W/m × 5 m = 48 W

1. 1. Add a safety margin (20–30%).

– With a 25% margin: – recommended_psu_min = 48 W × 1.25 ≈ 60 W

In this example, we would choose a 12V power supply rated at 60 W or higher, such as a 12V 75 W model. The key points:

• • The voltage must match (12V strip → 12V PSU).
  • The PSU’s wattage rating should be above the strip’s calculated power, with a margin.

In general:

• Safe_watts ≈ strip_watts × 1.2–1.3
• Or think of it as using only 80–90% of the PSU’s watts for the strip.

How to calculate how many LED strip lights one power supply can handle

Once you know how to size a PSU for one strip, you can extend the logic to multiple strips or runs.

At a high level:

> You can run as many LED strips as you like from one power supply as long as the sum of all strip wattages stays below a safe fraction (typically 80–90%) of the power supply’s rated wattage and the voltage matches.

General formula and worked examples

Let’s define:

• • PSU_watts = rated output watts of the power supply
  • margin_factor = 0.8 (80%) or 0.9 (90%)
  • safe_watts = PSU_watts × margin_factor
  • strip_power_i = wattage of strip i

Then:

• • Total_strip_watts = sum of all strip_power_i

And the key rule:

• • Total_strip_watts ≤ safe_watts

From this you can find:

• • Maximum number of identical strips:

max_strips ≈ safe_watts ÷ strip_power_single

• • Maximum total length (if you think in metres):

max_length ≈ safe_watts ÷ (W/m)

Example table (single strip type)

In Example 3:

• Each 5 m run uses 14.4 W/m × 5 m = 72 W.
• With five identical runs: 5 × 72 W = 360 W.
• A 24V 480 W PSU has safe_watts = 480 × 0.8 = 384 W, so 360 W is acceptable.

You can adjust the margin factor depending on how conservative you want to be and how critical the application is.

Handling mixed LED strip wattages on one power supply

Real projects often mix strip types (e.g. one run of RGBW, one run of single-colour). The good news is that the method does not change:

1. 1. Calculate or look up each strip’s wattage (W/m × length, or manufacturer’s total W per run).
   2. Add them all together to get Total_strip_watts.
   3. Compare that sum with safe_watts = PSU_watts × margin_factor.

Example:

• • Strip A: 12V RGBW, 14.4 W/m, 5 m → 72 W
  • Strip B: 12V single-colour, 9.6 W/m, 4 m → 38.4 W
  • Total strip load = 72 + 38.4 ≈ 110.4 W

If you use a 12V 150 W PSU:

• • safe_watts = 150 × 0.8 = 120 W → 110.4 W is acceptable.

If you plan to expand later, you may want a larger PSU or a second supply for future runs.

Wiring multiple LED strips to one power supply: series vs parallel

Multiple LED strips can share one power supply, but how you wire them is just as important as the arithmetic.

Is it safe to connect multiple LED strips to one power supply?

It is safe to connect multiple LED strips to one power supply if:

• • The supply voltage matches each strip’s voltage (e.g. 12V strips on a 12V supply).
  • The sum of all strip wattages stays within the safe_watts limit (80–90% of PSU rating).
  • The strips are wired using correct parallel connections, with cables and connections sized for the total current.

If any of these are wrong—especially voltage mismatch or overloading the power supply—you risk overheating, premature failure or tripping protections. When in doubt, choose a slightly larger PSU or split the load.

Why LED strips should be wired in parallel, not in series

For low-voltage LED strips, “series” wiring is often used loosely to mean daisy-chaining strips end-to-end. That approach quickly leads to problems:

• • The strip furthest from the supply sees lower voltage because of voltage drop along the copper traces and wires.
  • Brightness may gradually decrease along the run, and colour on RGB strips can shift.
  • One bad connection can affect everything “downstream”.

By contrast, parallel wiring means:

• • Each strip (or strip segment) connects back to the power supply’s output terminals so each sees essentially the same voltage.
  • In diagrams, this looks like multiple branches from the same PSU rather than one long chain.

Typical pattern with parallel wiring:

• Power supply + and – terminals → split into multiple branches via terminal blocks, distribution boards or splitter cables.
• Each branch feeds a strip (or short chain within its rated run length).
• You may inject power at both ends of longer strips, but those injections still come from the supply’s parallel branches.

Voltage drop, wire gauge and power injection with multiple LED strips

Even if your power supply is sized correctly, voltage drop and wire gauge can ruin performance on long runs or heavily loaded cables.

How and where to use power injection points

Power injection means bringing power into the strip at more than one point so that voltage stays high along its length.

Typical cases where injection helps:

• • A single long strip run (e.g. 10 m or 15 m) where feeding from only one end causes dimming at the far end.
  • Multiple strips that are physically far from the power supply but in the same zone.

Common strategies:

• • Feed from both ends – connect power at both ends of the strip run to halve the voltage drop along the copper traces.
  • Feed from the middle and ends – for very long runs, inject at the centre and endpoints.
  • Shorter segments + parallel feeds – instead of one 15 m run, use three 5 m runs, each fed from the PSU or via injection points.

Key reminders:

• Each injection point still draws from the same power supply, so all injections count towards the same total strip load.
• You must observe polarity and strip voltage, and ensure all returns (grounds) are common where required.

Choosing wire gauge and managing distance

Wire gauge (thickness) and distance both affect:

• • Voltage drop – thinner wires and longer distances drop more voltage for a given current.
  • Heat and safety – wires must be sized to safely carry the expected current.

High-level guidance (not a substitute for local code tables):

• • For short, low-current runs (e.g. a few amps, a few metres), modest wire sizes are often fine.
  • For higher currents or longer distances, use thicker cables and/or move the power supply closer to the loads.
  • If you notice measurable dimming between near and far strips, consider:

– Shorter runs per branch, – Higher strip voltage (e.g. 24V instead of 12V for long runs), – Extra power injection points, and – Thicker main feed cables from the PSU.

A voltage-drop calculator or tables from your cable supplier can help for critical and long-distance projects.

When to use several smaller power supplies instead of one large supply

Using a single large power supply for everything is not always the best idea. In many projects, using several smaller supplies is safer and easier to install.

Situations where multiple PSUs make sense:

• • Very high total load

– If one PSU would need to run near its maximum rating, consider splitting strips across two or more supplies to keep each one comfortably within its safe range.

• • Multiple zones or distant areas

– If strips are located far apart (e.g. different rooms, long corridors, multiple shelves), a single PSU might require long cable runs with significant voltage drop. – Local supplies reduce cable lengths and simplify troubleshooting.

• • Redundancy and maintenance

– In commercial or architectural installs, losing one big PSU can darken a large area. – Multiple smaller supplies limit the impact of a single failure and are easier to replace.

• • AC circuit loading and logistics

– Multiple PSUs can be spread across separate AC circuits or plugs if needed, helping keep within AC-side limits and simplifying wiring.

A useful rule of thumb:

> If your total DC load is approaching the upper end of a single supply’s rating or the physical layout forces long, messy cable runs, it’s worth considering two or more smaller power supplies instead of one large one.

AC plugs, outlets and circuit safety when powering multiple LED strips

On the AC side, the power supply appears as a load on the outlet or circuit. The circuit doesn’t “see” LED strips directly; it sees the sum of power supply input wattages.

High-level guidelines:

• • Check the input wattage or current of each power supply (often listed as input W or input A at 110–120V / 220–240V).
  • When multiple PSUs share the same outlet/circuit, add their input wattages to estimate total AC load.
  • Compare this total to the circuit rating and any applicable derating rules in your region (e.g. typical 15A/20A circuits in North America).

For small LED projects, a single supply or a few modest supplies usually sit well below circuit limits. For larger installations:

• • Consider distributing power supplies across multiple circuits.
  • Work with an electrician or follow your local electrical code if you are unsure where the line is.

Important: this article focuses mainly on the low-voltage DC side. AC-side design must follow local standards; when in doubt, treat the limits in this guide as conservative rules-of-thumb, not a replacement for local regulations.

Quick FAQ on powering multiple LED strips from one supply

How many LED strip lights can I run on one power supply? As many as you want, as long as the sum of their wattages stays below about 80–90% of the power supply’s rated wattage and the voltage matches. Calculate total strip watts from W/m and length (or per-strip wattage), and compare it to the safe portion of your PSU rating.

How do I calculate how many LED strips a power supply can handle? First, find the PSU’s safe watts (for example, safe_watts = PSU_watts × 0.8). Then calculate each strip’s power and sum them: total_strip_watts = Σ strip_watts. As long as total_strip_watts ≤ safe_watts, the supply can handle that number of strips.

Can I mix LED strips with different wattages on the same power supply? Yes, provided all strips are designed for the same voltage as the power supply and the sum of their wattages stays within the safe load limit. Just add up each strip’s watts (W/m × length or total W per run) and treat the total the same way you would for identical strips.

Can I run RGB/RGBW strips and amplifiers from one power supply? Yes. Each RGB/RGBW strip and amplifier has its own wattage requirement; you simply add them to the total load like any other strip. Make sure the power supply and wiring are sized for the combined power, and keep within your safe wattage margin.

How far can I run LED strips from the power supply? It depends on voltage, current and cable gauge. Higher voltages (e.g. 24V), thicker wires and power injection points allow longer runs. If you see dimming at the far end, consider shorter runs, higher voltage strips or more feed points.

When should I use more than one power supply? Use multiple supplies when your total load is high, when strips are spread over distant zones, or when you want redundancy and easier maintenance. Splitting loads can reduce voltage drop, simplify wiring and reduce the impact of a single supply failure.

Summary and key takeaways for powering multiple LED strips on one power supply

Designing a multi-strip system around one power supply is mostly about math and good wiring practice. Once you understand how to calculate load and apply simple safety rules, the decisions become straightforward.

Key takeaways:

• • Always match the voltage of your LED strips and power supply (5V, 12V, 24V).
  • Use watts per metre × length to calculate strip power and add strips together to get total load.
  • Keep total strip load below about 80–90% of the power supply’s rated wattage for safety and lifetime.
  • Wire multiple strips in parallel, not long daisy-chained “series”, and use power injection for longer runs.
  • Pay attention to wire gauge, distance and voltage drop, especially on the main feed cables.
  • For large loads, distant zones or critical applications, consider using several smaller power supplies instead of one large one.
  • On the AC side, always respect outlet and circuit limits and local codes; when in doubt, consult a qualified electrician.

If you need help choosing specific strip models and power supplies for a larger project, we can help you turn these principles into a complete system design.

You can explore our LED strip light range and our LED power supply range. For complex or multi-zone projects, you can also refer to our guide on how to connect multiple LED strips to one power source or contact us via our contact page to discuss the best setup for your application.