Plan your addressable LED installation before you build it.
Tell PixelPower what you’re building. It estimates the power, the supply to buy and where to feed the strip — and shows where every number came from. The example below is a real plan: change the numbers to make it yours.
I’m building of at ,
Change anything — the answer updates as you type.
What you need
91.5W
i
300 LEDs · 18.3 A at full white
could be 72.9 – 91.8 W
5 V · 25A
i
The nearest size sold, with 20 % kept in reserve
6
i
Evenly spaced feed points, both ends included
Works with 6 feed points. The strip’s own copper carries about 4 A, so one feed can’t supply 18.3 A. Fed as recommended, the estimate stays within limits. 2 other things to check below.
Needs attention
Each run draws up to 18.3 A, past the 4 A its own power trace is good for. Roughly 0.07 mm² of copper on a 10 mm strip — about the ampacity of 28 AWG. Push much past this into one end and the trace, or the connector feeding it, is what fails. Far below what the supply can deliver into a fault.
Feed it at several points — the injection plan says how many — and fuse each feed just above its own worst-case current. The supply's own limit is far above what this copper survives.
"Strip 1" has no fuse planned. Around 25 A would suit it.
Fuse every branch close to the supply. A supply’s own over-current threshold sits far above what LED wiring survives, so it is not protecting this cable.
The cable on "Strip 1" carries roughly 10 A, below the 18.36 A worst case.
4 mm² or thicker, or run a second pair in parallel. Ampacity also depends on bundling, ambient temperature and routing.
How it’s wired
Estimated voltage along the strip at full white · CalculatedMore, when you want it
Detailsranges, standby draw, running cost, why this supply
What it draws
Estimated maximum current
18.3 A
could be 14.6 – 18.4 A
Estimated maximum power
91.5 W
could be 72.9 – 91.8 W
Worst case: every channel of every pixel at full duty — the only figure a supply may be sized from. Medium confidence. Measuring one run at full white with a clamp meter replaces the estimate with a fact — the field is under Advanced settings.
- Pixels
- 300 over 5 m
- At typical content
- 6.60 A · 33.0 W
- With every LED off
- 0.300 A · 1.50 W
Average content draw is an estimate of what the installation usually does, not of what it can do. Use it for the electricity bill, never for a supply.
This is the floor, not the load.
Power supply
Recommended
5 V / 25 A (125 W)
Sized from 18.4 A — the top of the range for what is on this supply, not the headline figure — plus 0.15 A for the controller, with 20 % kept in reserve so the supply never runs at its thermal limit.
Show the arithmetic
- Worst case, top of range
- 18.4 A
- Controller
- + 0.15 A
- Required continuously
- 18.5 A
- Divided by 0.8 derating
- 23.1 A
- Nearest size sold
- 25 A
Running cost
7.3 kWh / month· 2.2 €
Drawn from the wall at 35 % average content, 6 h a day. 5.7 kWh of it is the LEDs; 0.27 kWh is the ICs idling, 0.14 kWh the controller, and 1.3 kWh is lost in the supply.
Wiring6 feed points · no supply configured · fuses and cable
Where the power goes
One row per protected branch · CalculatedFuse and cable are coloured by whether they suit the branch: suits it · check it · not protecting it. A rating with a ? is suggested — nothing is fitted yet. The taps that carry power into each strip are drawn above, not here.
Estimated voltage along the run
Evenly spaced, this run wants 6 feed points. If your strip sits at the thin end of its copper range and draws at the top of its current range, it would take 7 — unlikely to be both at once, but you buy the cable only once.
- Supply
- at the far end of the feed cable
- 5.00 V
- Feed at 0 m
- carries 18 A
- 4.16 V
- At 5.0 m
- unfed tail, 5.0 m
- beyond the model
Beyond what this model can estimate. The model predicts a drop of 566 % of the feed voltage. Past the configured 25 % it is no longer describing a working installation, so no figure is given. The strip copper is the limiting element here: add injection points or feed from both ends. Verify against the actual strip and cable specifications.
Compare layouts what another feed would buy
- No injection — fed at one end as planned
- beyond the model
- 2 evenly spaced feeds
- beyond the model
- 4 evenly spaced feeds
- 3.96 V(21 % drop)
- 6 evenly spaced feeds
- 4.56 V(8.8 % drop)
- 8 evenly spaced feeds
- 4.74 V(5.2 % drop)
Cable to each feed point 2 m of 1.5 mm²
The cable running to each injection point drops voltage too, and unlike the strip it carries the full current of that feed along its whole length. This is the tap after the strip’s power arrives — the cable from the supply itself is set per branch under Power distribution. Set the length to 0 to leave it out.
Thresholds where the bands sit
These are judgement calls, not physics. Around 10 % of the feed voltage, colour shift and dimming toward the far end become visible, and the rising ground shifts the data reference with it. Past 25 % the linear model is no longer describing a working installation, so no figure is reported at all. An architectural install holding a white tolerates far less than a party effect.
Power distribution
Power supply 5 V
- Strip 1 18.3 A · 91.5 W · 4.16 V at the load
no fuse planned — around 25 A would suit it. Cable: thinner than this branch needs (4 mm² or thicker).
Planning estimates, not an electrical design. A branch here is the cable from a supply to a load and the fuse protecting that cable — if you split that feed into several injection points, each tap needs its own protection too. Fuse and cable sizes are ordering guidance: real ampacity depends on insulation, bundling, ambient temperature and routing. PixelPower does not check any electrical code. Verify against the parts’ own datasheets and your local regulations.
Power supplies
No supply configured. PixelPower still recommends one — add a supply to check a capacity you already own, or to split the installation across several.
Layoutdraw the shape, several strips
1 strip has no shape, so it is not drawn — still counted in every total. Give it a shape below to place it.
5 m · 300 pixels. Drag a shape to move it. The picture is to scale; LEDs are drawn at their real spacing until they are too close together to tell apart.
ControllerGPIO, colour order, export for WLED
PixelPower can write the LED section of a WLED configuration from this project: the pixel count, one output per strip, the LED type, and a power budget from the supply you configured. Everything else in WLED is left exactly as you set it.
Outputs
- Strip 1 300 LEDs from index 0 · WS281x · 111 fps
Worth knowing
WLED's brightness limiter caps brightness to stay inside this budget. It is not a fuse and not a protective device.
A config reset, a firmware update, a wrong LED count or a crash removes it. Size the supply and the fusing for full white regardless — PixelPower does.
Preview the configuration 300 LEDs · 20.0 A budget
80 % of the 25.0 A PixelPower recommends, since no supply capacity was stated.
{
"hw": {
"led": {
"total": 300,
"maxpwr": 20000,
"ledma": 61,
"ins": [
{
"start": 0,
"len": 300,
"pin": [
16
],
"order": 0,
"type": 22,
"rev": false,
"skip": 0
}
]
}
}
}Sending writes the LED section of the controller’s configuration and applies it immediately. Nothing is sent unless you press the button. The power budget above is WLED’s brightness limiter — it caps brightness, it is not a fuse, and it does nothing about a short.
Parts10 lines · CSV and printable report
PixelPower states what each part has to do. It does not know what is on your shelf, so no product or supplier appears here unless you type one in.
- LED strip Strip 1 — WS2812B (5 V RGB), 60 LED/m 5 m · You entered
300 pixels at 5 V.
- Power supply 5 V 25 A power supply 1 piece · Recommended
18.51 A required ÷ 0.8 continuous derating = 23.137 A, rounded up to a 25 A supply.
- Controller ESP32 LED controller 1 piece · You entered
300 pixels across 1 output.
- Cable 1.5 mm² copper 28 m · You entered
Branch and injection runs, counted out and back.
- Fuse and holder 25 A fuse with holder 1 piece · Recommended
Smallest standard size above the worst case with the usual 1.25× margin. Nothing is planned for "Strip 1" yet.
- Fuse and holder 5 A fuse with holder 6 pieces · Recommended
One per injection point, sized for the busiest tap — an interior feed carries more than an end feed.
- Connector Injection connector or solder joint 6 pieces · Recommended
One per injection point, per run. Contacts add resistance — four at 5–30 mΩ are worth about a metre of strip copper.
- Data line 1000 µF electrolytic capacitor 1 piece · Recommended
Across the rail at the first injection point.
- Data line 300–500 Ω resistor 1 piece · Recommended
In series with the data pin, at the controller end.
- Data line Logic level shifter, 3.3 V to 5 V 1 piece · Recommended
A 5 V strip wants 3.5 V on its data line; an ESP32 GPIO gives 3.3 V.
Ordering guidance, not a wiring specification. A fuse has to sit above the load it feeds and below what its cable and connectors can carry, and real ampacity depends on insulation, bundling and how a run is routed. Check against the parts’ own datasheets and your local regulations.
Advanced settingsthe strip itself, how you drive it, your own figures
The strip itself
How you drive it
Where the power figures come from
Assumptions4 figures PixelPower had to guess at
Worth knowing
A 5 V strip wants at least 3.5 V on its data line, while an ESP32 GPIO delivers 3.3 V. It usually works, marginally, and fails intermittently.
Use a level shifter, a 300–500 Ω resistor in series with the data pin, and a 1000 µF capacitor at the first injection point. Common the grounds.
This result rests on 4 assumptions show
These are the figures PixelPower had to guess at, and they are why the range above is as wide as it is. Replace any of them with your strip’s datasheet — or better, a clamp-meter reading at full white — and the uncertainty it contributes disappears.
- 0.600 (0.450 – 0.900) Preset · Low confidence
A 10 mm strip with roughly 1 oz copper on both the +V and GND traces. The default, and about what most branded reels measure.
- 4.00 (2.00 – 6.00) Preset · Low confidence
Roughly 0.07 mm² of copper on a 10 mm strip — about the ampacity of 28 AWG. Push much past this into one end and the trace, or the connector feeding it, is what fails. Far below what the supply can deliver into a fault.
- 0.350 (0.100 – 0.550) Assumed · Low confidence
Typical animated content averages roughly 35 % of full white. Sparkle effects run near 10 %, slow rainbows near 55 %. Strongly content-dependent.
- 150 (80.0 – 250) Assumed · Low confidence
An ESP32-class controller with Wi-Fi active, 80–250 mA depending on the board and transmit duty.
What PixelPower works out
- Power calculation
Worst-case current and watts, with the idle floor and the range stated.
- Voltage drop
The estimated voltage at every point of the run, in the strip and in the cable.
- Injection planning
How many feed points, where, and what each one carries.
- Supply sizing
A supply you can buy, with headroom — or a check of the one you own.
- WLED export
The LED section of a WLED configuration, written from the same plan.
- Parts list
A bill of materials, a CSV and a printable report.