The short answer: 500 lx on the task
For general office work in the UK, the benchmark is BS EN 12464-1:2021, which sets a required maintained illuminance of 500 lx on the task area for writing, typing, reading and data processing. "Maintained" means the average must not drop below 500 lx at any point in the installation's life, so a new installation is normally designed to deliver more on day one to allow for ageing and dirt.
The legal duty is regulation 8 of the Workplace (Health, Safety and Welfare) Regulations 1992, which requires "suitable and sufficient" lighting but sets no numbers. HSE's HSG38 gives a safety minimum of 200 lx average for work requiring perception of detail, but that is a floor rather than a target. In practice, landlords, fit-out consultants and enforcing officers treat 500 lx as the office standard.
The full requirement for desk work
Lux is only one of eight criteria in the 2021 standard for general office tasks:
| Criterion | Requirement | What it means in practice |
|---|---|---|
| Ēm,r (required) | 500 lx | Minimum maintained average on the task area |
| Ēm,u (modified) | 1000 lx | Target where context modifiers apply |
| Uo | ≥ 0.60 | Minimum point at least 60% of the average |
| UGRL | 19 | Maximum discomfort glare rating |
| Ra | ≥ 80 | Colour rendering of the light source |
| Ēm,z (cylindrical) | 150 lx | Light on faces, for communication |
| Ēm,wall | 150 lx | Prevents a dim, enclosed feel |
| Ēm,ceiling | 100 lx | Avoids a "dark ceiling" effect |
The immediate surrounding area, a band at least 0.5 m around each task, should be at least 300 lx when the task is 500 lx. Where desk positions are not fixed, the whole working floor is usually treated as task area.
Office lux levels by area
Other office spaces have their own rows in the BS EN 12464-1:2021 schedule. Typical required values are:
| Area or task | Required maintained illuminance |
|---|---|
| Writing, typing, reading, data processing | 500 lx |
| Technical drawing | 750 lx |
| CAD workstations | 500 lx |
| Conference and meeting rooms | 500 lx |
| Filing and copying | 300 lx |
| Reception desk | 300 lx |
| Archives | 200 lx |
| Corridors and circulation | 100 lx |
Meeting rooms used for video calls need particular attention to cylindrical illuminance and modelling, because poorly lit faces look worse on camera than in person. The required lux lookup covers other spaces in mixed-use buildings.
When 500 lx is not enough
The 2021 edition introduced context modifiers that move the target towards the modified value of 1000 lx. Common office examples include:
- staff whose eyesight is reduced, including many people over 50;
- work with small print or low-contrast detail, such as reviewing drawings or contracts;
- tasks where errors are costly, such as financial or legal checking;
- long periods of uninterrupted concentration;
- deep-plan floors with little daylight.
Raising the general level is not the only answer. Dimmable lighting or individual task lights often meet these needs with less energy and less glare.
UGR 19 and screens
Glare is the most common reason staff complain about lighting that measures well. UGR 19 limits discomfort glare from luminaires in the field of view. The Health and Safety (Display Screen Equipment) Regulations 1992 add a duty to provide satisfactory lighting with appropriate contrast between the screen and its background, and to avoid disturbing glare and reflections on screens. Low-cost LED panels with bright, unshielded diodes are a frequent cause. See our DSE lighting guide and why employees complain about lighting.
CIBSE LG7: Offices (2023)
The Society of Light and Lighting's LG7 is the UK design guide for offices. The 2023 edition aligns its values with BS EN 12464-1:2021 and uses the same context-modifier approach. It moves the focus from a uniform working plane to the actual task area, reflecting how people work with laptops, tablets and phones, and adds advice on hybrid working, home offices, lighting controls and the embodied carbon of luminaires. LG7 also stresses wall and ceiling brightness: an office can meet 500 lx on the desk and still feel gloomy if vertical surfaces are under-lit.
Common office lighting failures we find
- Like-for-like LED swaps that hit the average but miss uniformity, because new panels have a different light distribution from the old fittings.
- Daylight dimming set too aggressively, pulling desks near windows below 500 lx on overcast days.
- Desk moves after fit-out that leave workstations between luminaires or in the shadow of storage.
- Dark finishes on walls and ceilings that fail the 2021 surface requirements.
- Glare from uplighters, bare LEDs or skylights reflecting in screens.
How an office survey is carried out
We measure with a calibrated, cosine- and colour-corrected meter at desk height, typically 0.7 to 0.8 m, on a grid sized to the area as the standard describes, rather than taking a handful of readings at chosen desks. Daylight is excluded where possible by surveying after dark or with blinds closed, so results reflect the electric lighting that has to perform in winter. Lighting controls are set to their normal occupied state and recorded. For each zone the report gives the average, the minimum and the uniformity ratio, compares them with the BS EN 12464-1:2021 row for that task, and notes visible glare sources, failed luminaires and any vertical surfaces that look under-lit. If the floor fails, the report shows where and by how much, which makes remedial quotes easier to compare.
Book an office lux survey
We measure office floors on a proper grid, report each area against BS EN 12464-1:2021 and LG7, and flag glare and uniformity issues alongside lux. An office survey for a single floor up to 250 m² starts from £175; prices are confirmed before booking. We cover offices across London and the South East. See office lux surveys or book a survey.
Frequently asked questions
How many lux does an office need in the UK?
BS EN 12464-1:2021 sets a required maintained illuminance of 500 lx on the task area for writing, typing, reading and data processing, with uniformity of at least 0.60.
Is 300 lux acceptable for an office?
Not for desk work. 300 lx is the minimum for the area immediately surrounding a 500 lx task and for filing, copying and reception desks, but general desk work requires 500 lx.
What does UGR 19 mean?
UGR is the Unified Glare Rating. A limit of 19 means the lighting installation should not exceed a glare rating of 19 from normal viewing positions, which is the standard limit for offices.
What is CIBSE LG7?
LG7 is the Society of Light and Lighting's guide to office lighting. The 2023 edition aligns with BS EN 12464-1:2021 and adds guidance on hybrid working, controls and sustainability.
How much does an office lux survey cost?
An office survey for a single floor up to 250 square metres starts from £175. The final price is confirmed before booking.