How many lumens does a bathroom need?
Updated
Bathrooms are small but need plenty of light in the right spot: the mirror. A single ceiling light behind you leaves your face in shadow exactly when you are shaving or putting on makeup.
For a bathroom of 5 m² (2.5 × 2 m, about 54 sq ft) with light walls, plan on about 3,800 lumens, roughly 40 W of LED. The recommended range is 150 to 250 lux for general light and 300–500 lux at the mirror.
Recommended lux for a bathroom
| Where | Illuminance | Color temperature |
|---|---|---|
| General room light | 150–250 lx | 3000K to 4000K |
| Mirror and vanity | 300–500 lx | 3000K to 4000K |
How many lumens by bathroom size
Total lumens to reach an average of 200 lux, adding up every bulb in the room. Watts are for regular LED bulbs (about 95 lm/W). 1 m² ≈ 10.8 sq ft.
| Area | Light walls | Mid-tone walls | Dark walls | LED (light walls) |
|---|---|---|---|---|
| 3 m² (32 sq ft) | 2,250 lm | 2,800 lm | 3,250 lm | ≈ 24 W |
| 4 m² (43 sq ft) | 3,050 lm | 3,700 lm | 4,350 lm | ≈ 32 W |
| 5 m² (54 sq ft) | 3,800 lm | 4,650 lm | 5,450 lm | ≈ 40 W |
| 6 m² (65 sq ft) | 4,450 lm | 5,400 lm | 6,350 lm | ≈ 47 W |
| 8 m² (86 sq ft) | 5,400 lm | 6,450 lm | 7,550 lm | ≈ 57 W |
Calculate for your room
Lighting tips
- Light your face from the front or the sides of the mirror, not only from above: overhead light casts shadows under the eyes.
- Near the shower, use fixtures rated for damp areas (IP44 or higher).
- Use 3000K–4000K with a good color rendering index (CRI 80 or more; 90 is better for makeup).
- Dark tiles absorb a lot of light: in that case, aim for the top of the range.
How the math works
Average illuminance (lux) is the light that reaches the work plane (table height, 0.75 m / 30 in), per square meter. Not all the light a bulb emits gets there: walls and ceiling absorb part of it, and LEDs lose output over time. The math follows the lumen method, the standard lighting design calculation:
lumens = lux × area ÷ (CU × MF)
- Room index (K): describes the room's shape. K = L × W ÷ [h × (L + W)], where h = ceiling height − 0.75 m. Small rooms and tall ceilings have a low K: more light hits the walls before reaching the table.
- Coefficient of utilization (CU): how much of the light reaches the work plane. It comes from a table that crosses K with wall reflectance (light ≈ 50%, mid-tone ≈ 30%, dark ≈ 10%), for a diffuse ceiling fixture and a white ceiling.
- Maintenance factor (MF): 0.8, to account for LED depreciation and dust.
Example: in a 2.5 × 2 m room with a 2.7 m ceiling (h = 1.95 m), K ≈ 0.57 and, with light walls, CU ≈ 0.33. For 200 lux: 200 × 5 m² ÷ (0.33 × 0.8) ≈ 3,800 lumens. Divided by 95 lm/W, that is about 40 W of LED.
The 3D simulator uses the same math, with the size and wall color you pick.
Read this before you buy
These numbers are an estimate for planning and comparing, not a lighting design. The math accounts for wall color, light loss over time and an average LED efficacy (95 lm/W), but it does not know which fixture you will use, its beam angle or where the furniture is.
- In the store, compare lumens on the box, not watts. Efficacy ranges from 80 to over 110 lm/W.
- Closed fixtures, frosted diffusers and dark shades deliver less light than the bare bulb.
- When in doubt, aim for the middle of the range and add a dimmer: you can turn light down, not up.
- For construction, major renovations or commercial spaces, talk to a lighting designer, architect or electrician.
Where the values come from
The math follows the lumen method in the IES Lighting Handbook (Illuminating Engineering Society) and CIE 52 on utilization factors. The lux ranges are comfort references for homes, based on ANSI/IES RP-11 (residential lighting), ISO/CIE 8995-1 / EN 12464-1 and the residential values of the former Brazilian standard NBR 5413. Workplace lighting standards do not regulate homes; treat the values as a starting point.
- The Lighting Handbook, 10th ed. (2011)
Illuminating Engineering Society (IES) · Lumen (zonal cavity) method, room index and coefficient of utilization. - CIE 52:1982 — Calculations for interior lighting: applied method
Commission Internationale de l’Éclairage (CIE) · Utilization factor from the room index and surface reflectances. - ANSI/IES/ALA RP-11-26 — Lighting for Interior and Exterior Residential Environments
IES / American Lighting Association · Recommended practice for home lighting: lux levels per room and task. - ABNT NBR ISO/CIE 8995-1:2013 — Iluminação de ambientes de trabalho, Parte 1: Interior
ABNT (Brasil) · ISO/CIE 8995-1 · Current Brazilian/ISO standard for indoor illuminance; basis for home office and circulation areas. - EN 12464-1:2021 — Light and lighting: Lighting of work places, Part 1: Indoor
CEN (Europa) · European counterpart, same concept of maintained average illuminance. - ABNT NBR 5413:1992 — Iluminância de interiores (cancelada em 2013)
ABNT (Brasil) · Replaced by NBR ISO/CIE 8995-1; still the most quoted residential lux reference in Brazil.
Frequently asked questions
How many lumens for a bathroom mirror?
To reach 300–500 lux on your face, plan on roughly 800 to 1,600 lumens for the mirror light alone, split between both sides or in a bar right above it, facing forward.
What bulb should I use in a bathroom?
LED at 3000K–4000K with CRI 80 or higher. Near the shower, the fixture must be rated for damp areas (IP44 or higher).
How many LED watts for a bathroom of 5 m² (54 sq ft)?
About 40 W of LED across all bulbs, for 3,800 lumens (200 lux with light walls). Efficacy varies between brands, so check the lumens on the box: that is what tells you how much light the bulb gives.
What color temperature for a bathroom?
3000K–4000K, with CRI 80 or higher so skin looks right in the mirror. To compare in practice, the 3D simulator lets you change each bulb’s color temperature and see the effect in the room.