A room lighting calculator tells you how many lumens you need for proper illumination. Different rooms require different light levels — kitchens need bright task lighting while bedrooms suit softer ambient light.
How to Calculate Room Lighting Needs
Lighting level is measured in foot-candles (fc) or lux. One foot-candle equals one lumen per square foot. Multiply the recommended foot-candles for your room type by the room's square footage to get total lumens needed.
Recommended Lighting Levels by Room
Living rooms and bedrooms: 10-20 fc. Kitchens: 30-40 fc general, 70-80 fc at counters. Bathrooms: 70-80 fc at mirror. Home offices: 50 fc. Hallways: 5-10 fc. These are general guidelines — personal preference and ceiling height also affect the final count.
FAQ
How many lumens per square foot do I need?
Recommended lumens per square foot vary by room: living room 10-20, bedroom 10-20, kitchen 30-40, bathroom 70-80, home office 30-50, hallway 5-10. Brighter tasks like cooking and reading need more lumens than relaxing spaces.
What is the difference between watts and lumens?
Watts measure energy consumption; lumens measure light output. An old 60W incandescent produces about 800 lumens. A modern LED uses only 8-10W to produce the same 800 lumens. Always shop by lumens, not watts.
How many recessed lights do I need?
Divide the total lumens needed by the lumens per bulb. For an 800-lumen (60W equivalent) bulb in a 12×14 room at 20 fc (foot-candles), you'd need about 336 lumens/sqft × 168 sqft = approximately 13-14 bulbs.
What is layered lighting?
Layered lighting combines ambient (general) light, task light (for work surfaces), and accent light (for visual interest). Relying on a single overhead fixture creates flat, uncomfortable lighting. Using three layers gives more flexible and pleasant results.
Is this calculator free?
Yes, completely free with no signup required.