The formulas, thresholds and assumptions behind every number the Power Calculator shows.
The Power Calculator turns a handful of inputs into a parts list. Every number it shows comes from the rules below. They run entirely in your browser, and nothing you enter is sent to a server. These are planning estimates. Always check the datasheet for your exact strip and supply, and use a fuse.
Total LEDs = strip length (m) × LEDs per metre.
Maximum current = total LEDs × current per LED ÷ 1000, in amps. This is the worst case, with every LED at full white. The per-LED figures used are:
| Chipset | Current per LED (full white) |
|---|---|
| WS2812B, WS2813, WS2801, LPD8806 | 60 mA |
| TM1814, WS2814 | 60 mA |
| APA102, SK9822 | 60 mA |
| SK6812 (RGBW), SK6813 | 80 mA |
| WS2811, WS2815, GS8208 (12 V types) | 15 mA |
| Generic / unknown | 60 mA |
If you enable the custom wattage option, maximum current is instead strip length × watts per metre ÷ supply voltage.
Strips rarely run at full white. The calculator multiplies the maximum by a usage profile: 100% (worst case), 70% (typical, the default) or 30% (mostly dim or coloured scenes). Real-world current = maximum current × profile. The fuse, wire gauge, injection spacing and power supply are all based on this value.
The fuse must sit above normal running current but still protect the wiring. The calculator takes real-world current × 1.25 and picks the next standard blade fuse size from 3, 5, 10, 15, 20 and 30 A (30 A is the largest it suggests).
Based on real-world current:
| Real-world current | Minimum wire gauge |
|---|---|
| under 5 A | 20 AWG |
| 5 A to under 12 A | 18 AWG |
| 12 A to under 20 A | 16 AWG |
| 20 A and above | 14 AWG |
For long runs also check voltage drop, which can require thicker wire than current alone.
The parts list suggests a supply rated at least 20% above real-world current, so it is not running at its limit. Matching products are drawn from the parts list for the selected voltage (5 V, 12 V or 24 V).
Data resistor (by data lead length between controller and strip):
| Data lead length | Suggestion |
|---|---|
| under 0.6 m | Optional, 249 Ω still recommended |
| 0.6 m to under 1.5 m | 249 Ω (220 Ω or 270 Ω also fine) |
| 1.5 m to 5 m | 470 Ω |
| over 5 m | 470 Ω plus a data booster |
Level shifter: QuinLED boards have one built in. For a data lead over 5 m a data booster is recommended. A generic or DIY ESP32 controller with a lead over 1.5 m should use an SN74AHCT125 level shifter, because the ESP32 outputs 3.3 V logic and 5 V strips expect a stronger signal. Otherwise none is needed.
Voltage falls along a strip, so long runs need extra power feeds. The calculator picks a spacing between injection points based on supply voltage and load:
| Supply voltage | Spacing (lighter load) | Spacing (heavy load) |
|---|---|---|
| 5 V | 5 m | 3 m (real-world current over 5 A) |
| 12 V | 7 m | 5 m (over 10 A) |
| 24 V | 10 m | 7 m (over 15 A) |
If the strip is shorter than the spacing it recommends injecting at the start only. Otherwise it lists injection points from the start every spacing distance, ending at the strip end.
If you enter a WLED current limit (mA), the calculator shows how much brightness you give up: brightness loss = 100 − (limit ÷ maximum current in mA × 100), never below zero.
5 m of WS2812B at 60 LEDs/m, 5 V, typical (70%) profile, ESP32 controller with a 1 m data lead.
Real strips vary by manufacturer, copper thickness and batch. The per-LED figures are planning values, not guarantees, and the calculator does not replace a datasheet, a qualified electrician or local electrical rules. If you find a figure that is wrong for a specific product, please tell us. Corrections are listed on What's New. Written and maintained by Alex, an electrical engineer (see About). Last reviewed October 2026.