KelvinPlanHow much light each room needs, and what colour it should be.

Lighting a 20 × 28 ft bathroom

Total light needed
19,600lumens
560 ft² × 35 foot-candles
Room area560ft²
Target light levelIES guidance for a bathroom35foot-candles
Total lumens19,600lm
Colour temperatureadd vanity lights at face height3000–4000K
Bulbs (800 lm each)25bulbs
Recessed cans (4 ft spacing)560 lm each35fixtures
Room
bathroom
Width
20 ft
Length
28 ft

Where 19,600 lumens comes from

Lighting is specified in foot-candles — lumens landing on each square foot of the surface you care about. A bathroom is worked to 35 foot-candles. Across 560 ft² that is 19,600 lumens in total.

Split it up

One fixture putting out 19,600 lumens and 35 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.

Colour temperature

3000–4000K suits this room. Warmer light reads as relaxed and is what you want where people wind down; cooler light keeps edges and colours crisp, which matters where there is work to do.

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 19,600 lm fixture and 35 smaller ones add up the same but look completely different.

Nearby sizes