Lux Levels for Homes and Offices: Lux Lighting Systems

Lux is the unit lighting designers use to answer a basic question: is there enough light on this surface to do this task comfortably? Understanding it helps you judge whether a kitchen worktop, desk or reading chair is properly lit, and it is the foundation on which all lux lighting systems — from a single home office to a whole commercial floor — are planned. Lux levels are not the whole story of good lighting, but without them it is easy to under-light work areas or flood living spaces with harsh light.

This guide explains what lux measures, the recommended levels for offices under Singapore’s lighting code, typical ranges used for homes, and the other factors — uniformity, glare and colour — that matter as much as the number.

What lux measures

Lux is the unit of illuminance: the amount of light falling on a surface. One lux equals one lumen spread over one square metre. If a light source emits a given number of lumens and they land evenly on a one-square-metre desk, the desk receives that many lux; spread the same light over four square metres and the illuminance drops to a quarter.

Illuminance is different from brightness as we perceive it. A white wall and a dark carpet can receive the same lux, but the wall looks far brighter because it reflects more. That perceived brightness is luminance, and it is why room colours affect how well lit a space feels.

To put lux in context, outdoor daylight ranges from a few thousand lux under heavy cloud to tens of thousands of lux in direct tropical sun. Indoors, most activities need a few hundred lux, which is why daylight near a window can easily exceed what electric lighting provides.

Office lux levels and SS 531

In Singapore, recommended lighting for indoor workplaces is set out in SS 531-1, the Singapore Standard code of practice for the lighting of indoor work places, which is adopted from the international standard ISO 8995-1. It gives maintained illuminance values, uniformity requirements, glare limits and colour rendering requirements for different tasks and spaces.

For offices, the commonly cited values from the standard include:

500 lux for writing, typing, reading and data processing, with a uniformity of at least 0.7 over the task area.
300 lux for filing and copying.
750 lux for technical drawing.

Uniformity is the ratio of the minimum to the average illuminance over the task area. A value of 0.7 means the darkest point on the desk should receive at least 70 per cent of the average, which avoids distracting patches of light and shadow. Circulation areas and corridors are typically set lower than workstations. For a specific project, the current edition of the standard should be consulted rather than a summary.

The values are maintained illuminance: the level that should be delivered throughout the life of the installation, after allowing for lamps dimming with age and fittings collecting dust. New installations are therefore designed to produce somewhat more than the target at day one. Our guide to office interior design places lighting within the wider fit-out.

Typical lux levels for homes

There is no mandatory lux standard for homes in Singapore, and good residential lighting is as much about mood and layering as quantity. Still, typical ranges used in practice give a useful sense of scale. The figures below are indicative ranges, not code requirements:

Living rooms (general): roughly 100 to 300 lux, with more at reading positions.
Reading and study: around 300 to 500 lux on the page or desk, usually from a task light.
Kitchen worktops: around 300 to 500 lux, with under-cabinet lighting to avoid shadows from wall units.
Bathrooms: modest general light, with brighter, even light at the mirror for grooming.
Bedrooms: low general levels of perhaps 50 to 150 lux, with brighter task light at wardrobes and dressing areas.
Corridors and stairs: enough for safe movement, typically 50 to 150 lux, with good light on stair treads.

Older eyes need noticeably more light for the same task, so a reading light suitable for a teenager may be inadequate for a grandparent. A practical approach is to provide adjustable task lighting rather than raising the whole room’s level. A balanced-arm desk lamp such as the classic Anglepoise lamp shows why: light brought close to the task delivers high lux where it matters with little energy.

Designing lux lighting systems

Lux lighting systems are designed by working backward from the target illuminance on the working plane — usually desk or worktop height — to the number, output, beam and spacing of fittings. In commercial projects, designers use lighting calculation software that models the room’s geometry, surface reflectances and the photometric data of each fitting. The output is a grid of predicted lux values, from which average levels and uniformity are checked.

The same thinking applies at home, even without software. Decide which surfaces need light and how much; provide ambient light for the room and task light where people work; and use dimming to adjust. Our guide to ceiling light design explains how to lay out fittings, and our home lighting design guide covers layering.

Daylight should be part of the design too. Near windows, natural light can exceed office targets for much of the day; daylight-linked controls dim fittings near the façade to save energy while maintaining the target level.

Beyond the number: glare, uniformity and colour

A space can meet its lux target and still be uncomfortable. Glare is the most common reason: bright sources in the field of view, reflections on screens, or harsh contrast between a bright desk and a dark surround. Lighting standards for workplaces therefore also limit discomfort glare, using a rating that accounts for the brightness and position of fittings relative to the viewer.

Uniformity matters both on the task and across the room. A desk lit to 500 lux in a room otherwise dim feels like a spotlight; some light on walls and ceiling makes the space feel balanced. Colour rendering — how naturally light shows colours — and colour temperature also influence comfort and should be consistent across a space. Workplace codes typically specify a minimum colour rendering index for offices.

Measuring lux levels

A handheld lux meter measures illuminance directly. Hold the sensor flat at the height of the task — on the desk or worktop — and keep your body from shading it. Measure at several points to gauge uniformity, and measure with daylight excluded if you want to know what the electric lighting alone provides. Smartphone apps can give a rough indication but vary considerably in accuracy.

If measurements show a shortfall, the cause is often fittings that have aged, are dirty, or are poorly positioned rather than too few. Where new circuits or fittings are needed, in Singapore the work must be carried out by a Licensed Electrical Worker licensed by the Energy Market Authority.

Frequently asked questions

How many lux does an office need?

For writing, typing, reading and computer work, SS 531-1 gives 500 lux maintained on the task area, with a uniformity of at least 0.7. Other office activities such as filing have lower values, and detailed drawing work higher.

How many lux is good for a living room?

There is no mandatory figure for homes. Around 100 to 300 lux of general light, with more at reading positions from a lamp, is a common and comfortable range.

What is the difference between lux and lumens?

Lumens measure the total light a source emits; lux measures how much of that light falls on each square metre of a surface. The same lumens produce fewer lux when spread over a larger area or a greater distance.

Can I measure lux with my phone?

Phone apps give a rough idea but are not reliable for design or compliance. A calibrated lux meter held at task height gives a far more accurate reading.

Do lux lighting systems need to be designed by a professional?

For workplaces, where codes set targets for illuminance, uniformity and glare, a lighting designer or engineer should prepare the calculations. For homes, sensible layering with task lights usually works well without formal calculation.

Fitting out an office or studio where lighting, ceilings and services must be coordinated? Talk to our consultancy or get in touch.