WS2812B power calculator

WS2812B is the most common addressable strip and the one whose figures come from a datasheet. It is also the one that punishes a single feed: 5 V and 61 mA per pixel means a 5 m run at 60/m cannot be fed from one end at all. The calculator estimates both the supply and the feed points.

You enter

I’m building m of at , run

Change anything — the answer updates as you type.

Calculated

91.5W

Estimated maximum power

Every channel of every pixel at full duty — the only figure a supply may be sized from. Based on the selected LED type and its preset figures; actual consumption depends on brightness, effects and conditions.

300 LEDs · 18.3 A at full white

could be 72.9 – 91.8 W

Recommended

5 V · 25A

Power supply

Sized from the top of the estimated range plus the controller, divided by 0.8 so the supply never runs at its thermal limit, then rounded up to a size that is actually sold.

The nearest size sold, with 20 % kept in reserve

Recommended

Power injection

Power weakens along the strip’s own copper. Feeding it in more than one place keeps the far end from dimming — this is the fewest evenly spaced feeds that stay inside your drop threshold.

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 · Calculated

Feed point — as recommended Strip colour: within limits · colour shift likely · power won’t reachWorst point: 4.56 V of 5 V

More, 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

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.

Hours lit per dayElectricity price (€/kWh) Supply stays on the rest of the day

Wiring6 feed points · no supply configured · fuses and cable

Where the power goes

One row per protected branch · Calculated

Fuse 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.

Injection points1 on a 5.00 m run

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.

Length to each feedThicknessPairs in parallel

What is the wire made of?Most cheap “18 AWG” LED wire is copper-clad aluminium.

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.

Consider more injection above (%)Report no figure above (%)

Power distribution

Total load91.5 Wacross 1 branch

Current18.3 Aworst case, every LED at full white

PixelPower recommends5 V · 25 Anone configured yet

Utilization—state a capacity to compare against

Power supply 5 V

Strip 1 18.3 A · 91.5 W · 4.16 V at the load
FuseCableLength
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.

StripShape

LabelLength (m)

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.

Controller boardController addressTyped in, not discovered: a browser cannot search a network for devices, and PixelPower has no server to do it from.

Outputs

Strip 1 300 LEDs from index 0 · WS281x · 111 fps
GPIOEmpty lets PixelPower pick: currently GPIO 16.Colour orderGRB unless the strip shows red where you asked for green.

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.

Open the printable report

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

Supply voltageLeave empty for the strip’s nominal 5 V.

How much copper is in the strip?Decides how far power travels before the far end dims, so it decides how many feed points you need. Nobody publishes it, so pick the closest.Exact LED count, if you counted them

How you drive it

Brightness — 255 of 255Affects the running-cost estimate only. A supply is always sized for full white, because brightness is a setting anyone can change back.

What is usually on screen?How does the brightness slider scale?

Where the power figures come from

UseA measurement of your own strip at full white replaces the biggest assumption on the page with a fact.What the seller claims (W/m)A listing’s W/m is usually arithmetic from the datasheet ideal, not a measurement. PixelPower compares it and says if they disagree.

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.

91.5 W needs 5 V · 25 A

Reference figures, 5 m at full white

Computed by the same engine as the calculator above, so they agree with it. Ranges reflect the spread between vendors. Verify against the actual strip and supply specifications.

Strip	LED/m	Pixels	Current	Power	Supply
WS2812B (5 V RGB)	30	150	9.15 A (7.29–9.18)	45.8 W	5 V · 15 A
WS2812B (5 V RGB)	60	300	18.3 A (14.6–18.4)	91.5 W	5 V · 25 A
WS2812B (5 V RGB)	144	720	43.9 A (35.0–44.1)	220 W	5 V · 60 A
SK6812 RGBW (5 V)	30	150	12.2 A (9.69–12.2)	60.8 W	5 V · 20 A
SK6812 RGBW (5 V)	60	300	24.3 A (19.4–24.4)	122 W	5 V · 40 A
SK6812 RGBW (5 V)	144	720	58.3 A (46.5–58.5)	292 W	5 V · 74 A

Amps per metre, honestly

The datasheet says 20 mA per channel. Production parts are binned low and commonly measure 16–20 mA, so PixelPower’s estimate is one-sided: 61 mA per pixel at the top, about 49 mA at the bottom, plus the 0.6–1.2 mA idle current that never switches off. At 60 LEDs/m that is roughly 3.7 A per metre at full white; at 144 LEDs/m, about 8.8 A per metre.

Sizing takes the top of that range. A supply sized from the middle is one good batch of LEDs away from running at its limit.

Why one feed is not enough

A 10 mm strip carries roughly 0.6 Ω per metre round trip through its own copper. Fed from one end, a 5 m run at 18.3 A would drop far more than the 5 V it started with — the formula gives 27 V — which is the model’s way of saying the run cannot be fed from one end. PixelPower reports no figure in that region, and instead tells you the fewest evenly spaced feeds that keep the drop within the threshold you set.

The strip’s copper trace is also only good for a few amps. Pushing 18 A into one end of a strip overloads the trace and the connector long before the supply notices.

Questions people ask

How many amps per metre does WS2812B draw at 60 LEDs/m?

About 3.7 A per metre at full white on 5 V, estimated range roughly 2.9–3.7 A/m. At 144 LEDs/m it is about 8.8 A/m. Verify against the actual strip and supply specifications before you buy or build.

How far can I run WS2812B from a single power feed?

On a typical 10 mm strip at 60 LEDs/m, colour shift becomes visible from a single end feed after roughly a metre, and a 5 m run cannot be fed from one end at all. The calculator estimates the drop for your run and how many feeds it wants — typically six for 5 m at full white.

Do I need a level shifter for WS2812B?

Usually. The data input wants at least 0.7 × the rail, or 3.5 V on a 5 V strip, and an ESP32 GPIO delivers 3.3 V. It often works marginally and fails intermittently; PixelPower lists a level shifter, a 300–500 Ω series resistor and a 1000 µF capacitor in the parts list for a 5 V strip.

What is the difference between WS2812B and SK6812 for power?

SK6812 RGBW has a fourth channel. Its worst case is all four dies on — about 81 mA per pixel, not the ~21 mA of the white die alone. Sizing from “white” undersizes by nearly 4×. The table on this page compares them at the same length.

Take the plan further

The answer above is the start. The full planner draws the layout, plans the branches, fuses and cable from each supply, writes a WLED configuration from the plan and produces a parts list and a printable report — all from the numbers you just typed, and nothing to sign up for.

Open the full planner Power injection, done properly Voltage drop along an LED strip

What you need

Needs attention

How it’s wired

What it draws

Power supply

Running cost

Where the power goes

Estimated voltage along the run

Power supply 5 V

Outputs

The strip itself

How you drive it

Where the power figures come from

Worth knowing

Reference figures, 5 m at full white

Amps per metre, honestly

Why one feed is not enough

Questions people ask

Take the plan further