How many lumens for a 20 × 20 ft basement?
Total light needed
12,000lumens
400 ft² × 30 foot-candles
| Room area | 400ft² |
|---|---|
| Target light levelIES guidance for a basement | 30foot-candles |
| Total lumens | 12,000lm |
| Colour temperatureraise it if the ceiling is low and dark | 4000K |
| Bulbs (800 lm each) | 15bulbs |
| Recessed cans (4 ft spacing)480 lm each | 25fixtures |
Notes
- Foot-candles are lumens per square foot at the work surface. Ceilings above 9 ft, dark walls or dark flooring all eat light — add roughly 10% per extra foot of ceiling height.
- Spread the total across several fixtures rather than one bright source. One 12,000 lm fixture and 25 smaller ones add up the same but look completely different.
Where 12,000 lumens comes from
Lighting is specified in foot-candles — lumens landing on each square foot of the surface you care about. A basement is worked to 30 foot-candles. Across 400 ft² that is 12,000 lumens in total.
Split it up
One fixture putting out 12,000 lumens and 25 fixtures adding up to the same number light a room very differently. A single source throws hard shadows and glare; several spread the light and make the room feel larger. Aim for layers — ambient, task, and something low for the evening.
Color temperature
4000K suits this room. Warmer light reads as relaxed and is what you want where people wind down; cooler light keeps edges and colors crisp, which matters where there is work to do.
Nearby sizes
Read more
- LED Dimmer Compatibility: The Four Checks Before You BuyCompatibility is not a mystery, it is four specifications. Check them before buying and you avoid the trial-and-error most people go through.
- Why LED Lights Flicker When Dimmed — and the Fix OrderThe dimmer is usually not broken and the bulbs are usually not faulty. They were designed for each other's opposites, and there are four fixes worth trying in order.
- CRI 90 vs 80: What the Ten Points Actually Cost YouTen points on a hundred-point scale sounds marginal. It is the difference between a room where the colours look right and one that feels vaguely tired.
- Colour Temperature Chart: Every Kelvin Value and Where It GoesThe scale runs backwards from intuition and the useful range is narrower than the chart suggests. Here is every value, what it reads as, and where it belongs.