Joyacy — Residential decorative lighting: how room size | joyacy.com
A room's lumen requirement is its floor area multiplied by a per-metre target — 100–200 lm/m² for living rooms, 300–500 lm/m² over kitchen work surfaces and 50–100 lm/m² in hallways.
The math is one line: lumens ÷ square metres = lux. A 20 m² living room at the 100–200 lm/m² band needs 2,000–4,000 lm from every source combined — ceiling light, floor lamps and pendants all count toward the same total.
Worked example: 1,500 lm spread over a 15 m² room gives 100 lux, a normal living-room level. The same 1,500 lm in a 30 m² room halves that to 50 lux, which is hallway territory — area, not bulb count, sets the result.
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Kitchens split in two. The room itself can sit near living-room levels, but the work surface needs 300–500 lm/m² — 300–500 lux on the bench — delivered by dedicated task lighting rather than a brighter ceiling fixture.
Hallways manage on 50–100 lm/m², about 50 lux at floor level. Bedrooms belong at the low end of the scale: stay near or under 100 lm/m² and put the savings into warm 2,700 K lamps and dimming, since the room is used at rest.
To turn a total into a shopping list, divide by the lumens on the label. An 800 lm LED bulb draws 7–10 W, so a 3,000 lm living-room target means roughly four such bulbs across fixtures; a 5–7 W GU10 LED spot contributes about 600 lm, matching the 50 W halogen it replaces.
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