Every lit costume lives or dies on one division. Hours = mAh ÷ mA-draw, from the wearable LEDs guide — and the drawing of it is the whole plan.
A single-color strip pulls about 0.4 A per meter; analog RGB about 0.6 A; an addressable NeoPixel strip about 1 A at white. Multiply by your meters, get your draw. The classic then follows: a 10,000 mAh bank on a 1 A build is about 7 honest hours with the inefficiency margin already paid.
Full white is a photo mode, not a con mode — the guide's own line. Pre-made presets dimmed to 30–50% look identical in a dim hall and stretch that same bank into the evening; the guide's rule of thumb: plan the dimmed draws and double the hours you computed. That gap is what gets you from the 7 pm dead battery to the doors-actually-closing one.
Inject power every 2 m so the far end of the strip stays bright; hot-glue strain relief on the joints (con floors kill loose ones); quick-disconnect at the battery so charging never un-builds the costume. The LED battery cheat sheet carries the table for the bench; the costume lab does the math with your real numbers.
Hang the mask. — the workshop crew
