A reference for illuminance targets across every building and room type. Covering IES, EN 12464-1, and the WELL Building Standard — with lighting power density guidance and practical specification notes.
The SI unit of illuminance — the amount of light arriving at a surface. This is what you specify and measure.
The imperial equivalent, still standard in North American practice. One lumen per square foot.
Over-lighting causes glare, fatigue, and wasted energy. The goal is appropriate light for the task and context — no more, no less.
The table below gives recommended maintained illuminance levels — the minimum average lux on the task plane (usually the working surface) once lamp depreciation and dirt are accounted for. These are not ceiling values; they’re the light that actually reaches where people work.
For most spaces, the task plane is a horizontal surface 0.75m (desk height) above the floor. For corridors and circulation, it’s the floor. For wall-mounted displays, it’s the vertical plane at the item.
Lux needed × Area (m²) ÷ (CU × LLF) = Total lumens required
CU = Coefficient of Utilisation (typically 0.4–0.8). LLF = Light Loss Factor (typically 0.7–0.9). These vary by fixture, room geometry, and maintenance schedule.
Values shown are ranges. Use the lower end for general activity in the space; the upper end for detailed or contrast-sensitive tasks. Where standards differ, we show both and note the source.
| Space / Task | Lux | Bar | Standard | Notes |
|---|
Numbers alone don’t convey how light actually feels. This scale maps common lux levels to experiences you already know — from a moonlit night to full daylight.
Published by the Illuminating Engineering Society. The primary North American reference for illuminance recommendations. Values are given in foot-candles with lux equivalents.
The European standard for lighting of indoor workplaces. Specifies maintained illuminance, uniformity ratios, and glare limits (UGR) for a comprehensive range of spaces.
Adds circadian lighting requirements. Feature L03 specifies melanopic equivalent lux (EML) targets at the vertical plane at eye level — a different measurement from task illuminance.
Sets maximum Lighting Power Density (LPD) in watts per square metre. These are energy caps, not illuminance recommendations — but they constrain what you can achieve.
Getting lux levels right isn’t just about hitting a number on a table. Here are the errors we see most often in practice.
Measuring on the wrong plane. IES and EN 12464 specify illuminance on the task plane — usually a desk at 0.75m. The WELL Building Standard measures melanopic lux on the vertical plane at 1.2m (eye level). These are fundamentally different measurements and cannot be compared directly. Confusing them is the single most common error in circadian lighting specifications.
Over-lighting is as problematic as under-lighting. Spaces lit well above recommended levels waste energy, increase glare risk, and can actually reduce visual comfort. A corridor lit to 300 lux when 100 is adequate creates unnecessary adaptation demands when occupants move between spaces.
Surface reflectance dramatically affects perceived brightness. A room with dark walls and furniture needs measurably more lumens to achieve the same task illuminance as one with light surfaces. If you’re specifying for a space with walnut panelling and dark carpet, budget accordingly — the same fixture layout that works with white walls may fall short by 30% or more.
Uniformity matters as much as average illuminance. EN 12464-1 specifies a minimum uniformity ratio (U₀) for each space type — typically 0.4 to 0.7. A space with 500 lux average but poor uniformity (bright spots and dark patches) is less comfortable than one with 400 lux evenly distributed.