In short
What the Unified Glare Rating means, why UGR19 is the benchmark for offices, and how linear luminaires are designed to meet it.
Glare is the most common complaint in badly lit offices, and it is rarely about how much light there is. It is about how bright the luminaire looks against its surroundings. The Unified Glare Rating (UGR) is how designers put a number on that discomfort.
What UGR measures
UGR is calculated from the luminance of every visible luminaire, its position in the field of view, and the background luminance of the room. The result sits on a scale from about 10 (imperceptible) to 30 (intolerable). Lower is better.
| UGR | Typical application |
|---|---|
| ≤ 16 | Technical drawing, detailed visual work |
| ≤ 19 | Offices, classrooms, reading and screen work |
| ≤ 22 | Circulation, reception, light industry |
| ≤ 25 | Storage, heavy industry |
Why UGR19 matters for offices
BS EN 12464-1 sets UGR 19 as the limit for office tasks such as writing, typing and screen work. For most UK workplace schemes it is a pass-or-fail requirement, and it is often written directly into the specification.
How linear luminaires achieve it
- Microprismatic diffusers redirect light downward and cut high-angle brightness.
- Louvres and low-glare optics, like those in Aril, physically shield the LEDs.
- Direct/indirect distribution brightens the ceiling, raising background luminance and lowering contrast.
- Layout: luminaire orientation relative to desks changes the result, so UGR must be checked for the actual room, not just the catalogue.
Ask for a room-specific calculation
A catalogue UGR value is calculated for a standard room. We run glare analysis on your real layout as part of every scheme. See specifier support.
Further reading at 299 Lighting
Next steps on linear-led.com
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Start a project →Frequently asked questions
What does UGR19 mean?
UGR19 means the Unified Glare Rating of the lighting installation is 19 or lower, the limit BS EN 12464-1 sets for offices and screen-based work.
Is a lower UGR always better?
Lower UGR means less discomfort glare, but very low values can require optics that reduce efficiency or make a space feel flat. The goal is to meet the task requirement with the right balance.
