What lux level is required for an office?

BS EN 12464-1 typically requires 500 lux maintained for general office work with computers. Meeting rooms and circulation spaces are lower — confirm the brief.

How do I calculate the number of luminaires needed?

Use the lumen method: E = (N × Φ × UF × MF) / A. Enter room area, target lux, luminaire lumens, and utilisation/maintenance factors.

What is maintained vs initial illuminance?

Maintained lux accounts for lamp depreciation, dirt, and room surface losses. Always quote maintained values on issued designs.

BuildFlo Design Guide · Lighting · BS EN 12464-1

Lux level calculator for lighting design

Size luminaires or check maintained illuminance against BS EN 12464. Free UK lux level calculator for offices, classrooms and corridors.

What this calculator does

Lux levels helps UK building services engineers with lumen-method sizing, maintained lux checks, bs 5266 emergency and lpd. The calculation follows BS EN 12464-1 methods used in everyday MEP design — enter your project inputs below for a first-pass result.

Whether you searched for "lux levels", "lux levels calculator", or "how to lux levels", this page gives you a working tool plus the context to use it on a real job.

When to use it

Use this for early-stage sizing and sanity checks on UK building services work. It is not a substitute for issued calculations — verify against the project specification, drawings, and relevant standard before sign-off.

How to use it

1. Fill in the inputs for your scenario (defaults are starting points only). 2. Click Calculate — results include the method and assumptions where applicable. 3. Verify against the project specification and relevant standard before issuing.

Typical output unit: lux.

Lux levels calculator

Lumen-method sizing, maintained lux checks, BS 5266 emergency and LPD

Calculation modeSpace type

Sets indicative BS EN 12464 maintained lux

Room area (m²)Target maintained illuminance (lux)

BS EN 12464 maintained illuminance

Luminaire output (lm)Number of luminaires

For checking lux or emergency from a given layout

Utilisation factorMaintenance factorEmergency typeTotal lighting power (W)

For LPD mode

All calculators →Save results in BuildFlo →

Tips

Defaults are indicative — replace with project-specific values from the architect, structural, or MEP spec.
For issued calculations, save results in your BuildFlo project and attach to the calculation folder.
Need the regulation citation? Open BuildFlo chat in the app and ask about lux levels under UK standards.

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Frequently asked questions

What lux level is required for an office?: BS EN 12464-1 typically requires 500 lux maintained for general office work with computers. Meeting rooms and circulation spaces are lower — confirm the brief.
How do I calculate the number of luminaires needed?: Use the lumen method: E = (N × Φ × UF × MF) / A. Enter room area, target lux, luminaire lumens, and utilisation/maintenance factors.
What is maintained vs initial illuminance?: Maintained lux accounts for lamp depreciation, dirt, and room surface losses. Always quote maintained values on issued designs.