How many lumens do I need for a room?

It depends on room type and activity: Living room 1,500-3,000 lumens (10-20 lm/sqft), Kitchen 3,000-4,000 (30-40 lm/sqft), Bathroom 4,000-8,000 (60-70 lm/sqft for vanity), Bedroom 2,000-4,000 (10-20 lm/sqft), Office/study 3,000-6,000 (30-50 lm/sqft), Garage 10,000-20,000 (50-100 lm/sqft). Multiply room area (sqft) by recommended lumens per sqft.

How do you convert lumens to watts?

Depends on bulb type. LED: 1 watt ≈ 80-100 lumens. CFL: 1 watt ≈ 55-70 lumens. Incandescent: 1 watt ≈ 12-15 lumens. Halogen: 1 watt ≈ 16-20 lumens. Example: to get 800 lumens — LED needs 8-10W, CFL needs 13W, incandescent needs 60W. Always compare lumens (brightness), not watts.

What is the difference between lumens, lux, and foot-candles?

Lumens = total light output from a source. Lux = lumens per square meter (brightness at a surface). Foot-candles = lumens per square foot. Conversions: 1 foot-candle = 10.764 lux. A 1,000 lumen bulb in a 10 sqm room = 100 lux. Lux/foot-candles measure how bright a surface is; lumens measure how much total light a source produces.

What color temperature should I choose?

2700K (warm white): living rooms, bedrooms — cozy, relaxing. 3000K (soft white): kitchens, bathrooms — warm but functional. 3500K (neutral): offices, retail. 4000K (cool white): garages, workshops, kitchens — bright, energizing. 5000K+ (daylight): task lighting, art studios, reading. Most homes use 2700-3000K. Match all bulbs in a room to the same color temperature.

What is CRI and why does it matter?

CRI (Color Rendering Index) measures how accurately a light source reveals colors compared to natural light. Scale 0-100, with 100 being perfect (sunlight). Look for CRI 80+ minimum, CRI 90+ for kitchens, bathrooms, closets, and anywhere color accuracy matters (makeup, cooking, art). Low CRI makes colors look dull and washed out.

How to calculate recessed light spacing?

General rule: spacing = ceiling height ÷ 2. For 8ft ceiling: space lights every 4 feet. Place first row 2-3 feet from walls. For a 12×16 room with 8ft ceilings: 3 rows × 4 lights = 12 recessed lights (4 inch spacing). Adjust based on beam angle — narrow beam (25°) needs closer spacing, wide beam (60°+) can be farther apart.

Lumen Calculator — Free Lighting Design & Room Brightness Tool | AllInOneTools

⚡ Electrical & Energy

Lumen Calculator

Calculate how many lumens you need for any room. Convert lumens↔watts↔lux↔foot-candles with recommended lighting levels and bulb count planner.

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Lumens Needed

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LED Bulbs (800 lm)

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lm/bulb

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Lighting Breakdown

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Unit Conversions

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Frequently Asked Questions

How many lumens for a room?▼

Living room: 10-20 lm/sqft, Kitchen: 30-40, Bathroom: 60-70, Bedroom: 10-20, Office: 30-50, Garage: 50-100. Multiply room sqft by recommended lm/sqft.

Lumens to watts conversion?▼

LED: 80-100 lm/W. CFL: 55-70 lm/W. Incandescent: 12-15 lm/W. For 800 lumens: LED=8-10W, CFL=13W, incandescent=60W. Compare lumens, not watts.

Lumens vs lux vs foot-candles?▼

Lumens = total light output. Lux = lumens per m². Foot-candles = lumens per sqft. 1 fc = 10.764 lux. Lumens for total brightness; lux/fc for surface brightness.

How many LED bulbs for a room?▼

Total lumens needed ÷ lumens per bulb. Example: 168sqft office × 40 lm/sqft = 6,720 lm ÷ 800 lm/bulb = 8-9 bulbs. For recessed lights: space every 4-6 feet.

What color temperature?▼

2700K warm white: living/bedrooms. 3000K soft white: kitchens/baths. 4000K cool white: garages/workshops. 5000K daylight: task/art. Match all bulbs in a room.

What is CRI?▼

Color Rendering Index (0-100). Measures color accuracy vs sunlight. CRI 80+ minimum, 90+ for kitchens/baths/closets. Low CRI makes colors look washed out.

Recessed light spacing?▼

Spacing = ceiling height ÷ 2. 8ft ceiling = 4ft spacing. First row 2-3ft from walls. 12×16 room: ~12 recessed lights. Adjust for beam angle (narrow=closer, wide=farther).