How Many Lumens Do You Need? Lighting Levels for Offices, Warehouses, Shops and Car Parks

"How many lumens do I need?" is the most common question a lighting supplier hears, and the honest answer starts with a different unit. Standards do not specify lumens; they specify lux — the light arriving on the desk, the floor or the rack face. Lumens are what a fitting produces. The job is to get from the lux a space needs to the lumens, and the number of fittings, that will deliver it. This guide gives the lux figures for the most common commercial spaces, then a method for converting them that holds up well enough for budgeting and shortlisting.

Recommended lux levels by space

The figures below are the maintained illuminance values in BS EN 12464-1 (indoor workplaces) and BS EN 12464-2 (outdoor), which are what a UK lighting design is calculated against. "Maintained" means the level that must still be there at the end of the maintenance cycle, not on day one.

• Offices: 500 lux on the desk for writing, typing and reading; 300 lux for filing and copying; 500 lux in meeting rooms; 300 lux at reception; 100 lux in corridors.
• Warehouses and logistics: 100 lux in store rooms; 150 lux in manned racking aisles (20 lux where unmanned); 300 lux in packing, dispatch and inspection areas.
• Industrial: 200 lux for rough assembly, 300 lux for medium, 500 lux for fine work and 750 lux or more for precision assembly and inspection.
• Retail: 300 lux across the sales floor; 500 lux at tills and wrapping counters; higher, focused accent lighting on displays.
• Education: 300 lux in classrooms under UK school guidance, with BS EN 12464-1:2021 now listing 500 lux (300 lux kept for nursery rooms); 500 lux in labs, art and practical rooms; good vertical light on the whiteboard.
• Healthcare: 100 lux general ward lighting; 300 lux for reading and simple examinations; 1,000 lux in examination and treatment areas.
• Car parks: 75 lux in covered parking bays and traffic lanes, with 300 lux at entrance and exit ramps by day; outdoors, 5 to 20 lux depending on traffic, with uniformity of at least 0.25.
• Sports halls: 300 lux for school and community use; more for competition, as set out in BS EN 12193.

From lux to lumens: the lumen method

Lighting designers use a formula called the lumen method. The number of fittings needed is the required lux multiplied by the floor area, divided by the lumens per fitting multiplied by two correction factors: the utilisation factor (UF), which is the fraction of the fitting's light that actually reaches the working plane rather than the walls and ceiling, and the maintenance factor (MF), which allows for LED depreciation and dirt over time. UF depends on the room shape, surface colours and the fitting's optics and typically falls between 0.4 and 0.8; MF is commonly 0.8, lower in dirty environments.

Written out: number of fittings = (lux × area) ÷ (lumens per fitting × UF × MF).

A 1,000 m² warehouse to 200 lux, using high bays delivering 20,000 lumens each, with UF 0.6 and MF 0.8: (200 × 1,000) ÷ (20,000 × 0.6 × 0.8) = 200,000 ÷ 9,600, or about 21 fittings. A 200 m² open-plan office to 500 lux, using 600 × 600 LED panels of 3,600 lumens, with the higher UF of 0.75 that recessed panels achieve in a light-finished room and MF 0.8: (500 × 200) ÷ (3,600 × 0.6) = 100,000 ÷ 2,160, or about 46 panels — roughly one for every 4.5 m², which is why a good office ceiling looks busier than people expect.

A shortcut for budgeting: lumens per square metre

For a first estimate, divide the required lux by a combined factor of around 0.4 to 0.5 (UF × MF), which gives the luminaire lumens per square metre the space needs. The rule of thumb that falls out is simple: multiply the lux figure by roughly two to two and a half. Efficient recessed fittings in a bright room will need less; high ceilings, dark finishes and dirty environments will need more.

• A 500 lux office needs around 1,000–1,250 luminaire lumens per m² — for 100 m², about 100,000–125,000 lumens in total.
• A 300 lux shop floor or classroom needs around 600–750 lumens per m².
• A 200 lux warehouse aisle needs around 400–500 lumens per m²; a 150 lux one, 300–375.
• A 100 lux corridor or store room needs around 200–250 lumens per m².
• A 75 lux covered car park needs around 150–190 lumens per m², though uniformity and vertical light for CCTV usually push the real design higher.

Two cautions. Use luminaire lumens — the light that leaves the fitting — not the LED chip figure, a distinction explained in our guide to reading a datasheet. And remember that mounting height changes the optic you need, not the lumens per square metre: a 12 m warehouse roof needs narrower beams than a 6 m one to put the same light on the floor, as covered in our high bay design guide.

Standards specify lux on the surface. Fittings are sold in lumens. Multiply the lux by two to two and a half per square metre and you have a budget figure that is rarely far wrong.

The shortcut gets a project to a sensible shortlist and a realistic budget. The design itself should still be a photometric calculation of the real room, with the real fittings' IES or LDT files, because that is the only way to know the uniformity and glare figures the standard also asks for. Every range in the Regents LED catalogue has its photometric data available on request, and our engineers will run the calculation for a specific building without charge.