Light measurement uses different units to describe how light travels, hits a surface, or emanates from a source. Below is the difference between the two most common units: Lux (illuminance) and cd/m² (lubricity).

Illumination – Unit: Lux (lx)

Lux measures the amount of light. project A unit of surface area (1 lx = 1 lumen/m²). This is an important parameter for determining whether a space has enough light for work or living.

Device for measuring light intensity testo 540 (0 to 99999 Lux)

• Meaning: Indicates whether the surface is brightly or dimly illuminated.
• Application: Lighting design for homes, offices, and schools.
• Reference standard:
  • Bedroom: 100 – 150 lux.
  • Living room/Dining room: 200 – 300 lux.
  • Classroom/Workroom: 300 – 500 lux.
  • Natural sunlight: 32,000 – 100,000 lux.

Brightness – Unit: cd/m² (Nits)

Nits cd/m² measuring light emitted or reflected from a surface in a certain direction. 

• Meaning: This indicates how bright an object (such as a screen or light) appears to the human eye. The higher this number, the brighter the surface and the more likely it is to cause glare.
• Application: Measure the brightness of phone screens, laptops, TVs, or LED advertising displays.
• Conversion: 1 cd/m² also known as 1 Nit.

Topcon BM-9A (BM-9A20D) LED display light intensity meter (0.01~280,000 cd/m²)

Choosing between measuring illuminance (Lux) or luminance (Nits cd/m²) depends on whether you want to know how much light the surface receives or how much light it emits/reflects into the viewer's eye..

You need to measure Lux when the goal is to ensure a space or surface has sufficient light to carry out specific activities. 

KONICA Minolta T-10A, T-10MA Brightness analyzer 0.01 ~ 299,000 lx

• Interior lighting design and testing: Ensure that the lighting meets standards for areas such as offices and classrooms.300~500 lx), or housing.
• Workplace safety: Check whether the lighting intensity at workstations and production lines is sufficient to ensure workers can operate safely without eye strain.
• Agriculture and filmmaking: Measure the actual amount of light that falls on plants to optimize photosynthesis, or the amount of light that falls on subjects in photography/film to adjust camera settings.
• Public lighting: Check the illumination levels on roads, sidewalks, or in parking garages to ensure traffic safety and security.

HIOKI Simplify Lighting Inspections with Multi-Point Lux Measurement | Lux Meter FT3425

When is it necessary to measure luminance (cd/m²)?

You need to measure luminance (Nits) when you are interested in... sense of brightness of the human eye to a light source or a reflective surface. 

• Check the device screen: Measure the brightness of your phone, computer, TV, or LED advertising display screen to ensure it's bright enough to be clearly visible in various environmental conditions.
• Glare control: Assess whether lighting or reflective surfaces (such as wet pavements or glass walls) cause glare, discomfort, or danger to viewers.
• Traffic signs and lights: Ensure that traffic signs or traffic lights are bright enough to be easily seen from a distance without causing glare.
• Intensive street lighting: Besides illuminance, road glare is an important indicator for assessing lighting quality, helping drivers to see obstacles better.

Detailed comparison table of illuminance (Lux) and luminance (Nits) measurement standards.

The relationship between the two units of measurement: illuminance (Lux) and luminance (cd/m²).A surface with high illuminance (Lux) will typically have high luminance (cd/m²), unless the surface is extremely dark (absorbing all light). In street lighting engineering, Lux is used to ensure safety (visibility of obstacles) and cd/m² is used to ensure drivers are not blinded by headlights or road reflections.

Contact SEMIKI Measuring Equipment Co., Ltd. To choose and purchase light measuring equipment, SEMIKI is a reputable company with many years of experience in the field of precision measuring equipment in Vietnam.

Here are some reasons you might consider choosing SEMIKI for your Lux and Luminance meter needs:cd/m²):

• Authorized distribution partnerSEMIKI is a distributor of products from many leading global brands that you may be interested in, including: TESTO (Germany) and TOPCON (Japan).
• Product catalog meets requirements:
  • Measure illuminance (Lux): We offer popular models such as testo 540 (compact) testo 545 (App connectivity), and the high-end Topcon IM-600 model.
  • Luminance measurement (cd/m²): Flow distribution Topcon BM-9A, specialized equipment for integrated measurement systems and production lines.
• Experience and reliabilitySEMIKI is recognized as a reliable provider of measurement solutions for the mechanical and electronics industries.
• Good support serviceIn addition to selling equipment, the company also provides repair services and in-depth measurement solution consulting, helping you choose the right model to suit your budget and technical requirements.

Contact Semiki:

Website: You can find out more details and send a consultation request via Semiki.com.

Business email: [email protected]

Phone number (Hotline): +84 979 761 016.