Photometric sheets · 60 footprints × 12 targets

How many lights
does this room need?

Fixture count, centres, and a to-scale ceiling plan with the light's own falloff drawn on it — worked with the lumen method rather than a rule of thumb. Free, no signup.

Footprints60each drawn to scale

Targets12one per room use

Sheets720with contours drawn

SOURCE·IES lumen-method recommendations·published recommendations, quoted as ranges·REVIEWED JUL 2026

Specimen sheet · 12 × 14 kitchenWhat every page on this site looks like

The plan is to scale. The dashed rings are iso-lux contours: one fitting's own light falling from 108 lux beneath it to 27 lux 5 ft away. They have to overlap before the room reaches 300 lux, and that is what sets the count at 12.

Fitting, 800 lm 81 lx 54 lx 27 lx Contours: one fitting, direct only

SOURCE·Computed from the lumen method·no dataset, every figure reproducible with a calculator·REVIEWED JUL 2026

The full sheet for this room →

Index · footprintsStart from the dimensions you measured

12 × 12 ft room144 sq ft · all room types 10 × 12 ft room120 sq ft · all room types 12 × 14 ft room168 sq ft · all room types 14 × 16 ft room224 sq ft · all room types 10 × 10 ft room100 sq ft · all room types 16 × 20 ft room320 sq ft · all room types 12 × 16 ft room192 sq ft · all room types 20 × 20 ft room400 sq ft · all room types

Index · targetsOr start from what the room is for

Kitchen 300–500 lxLiving room 150–300 lxBedroom 100–200 lxBathroom 200–300 lxHome office 400–500 lxDining room 150–300 lxGarage 150–300 lxHallway 100–200 lxLaundry 200–300 lxBasement 150–300 lxWorkshop 500–750 lxNursery 100–200 lx

PositionWhy "one light per 4 square feet" gets it wrong

Almost every lighting calculator online uses a fixed rule: so many watts or fixtures per square foot. It is quick, and it is fine for an ordinary 8-foot-ceiling bedroom. It falls apart everywhere else.

Two rooms with identical floor areas can need very different amounts of light. A tall room loses more of it before it reaches the floor. A long, narrow room bounces less light off its walls than a square one — that relationship is captured by the room index, and it moves the answer by 30% or more between a cramped hallway and a large open space. And a kitchen is lit to roughly double a living room regardless of size.

This site runs the actual lumen method for every combination and draws the result, because the useful answer was never the number on its own — it is where the fittings go and how far each one's light actually gets.