What Is a Lux Meter? How to Measure Illumination Accurately
Is the lighting in your workspace really bright enough? And is your resting environment truly dark enough? A lux meter, also known as an illuminance meter, is an instrument used to measure light intensity. It can help you address various concerns related to lighting levels and visual comfort. In the following sections, we will provide a comprehensive introduction to the lux meter—including lux meter working principle, the differences between a lux meter and other light-measuring devices (such as light meter vs lux meter), typical lux meter applications, how to choose the right model, and practical tips on how to use a digital lux light meter correctly.
What Is a Lux Meter
Illuminance refers to the amount of visible light received per unit area, describing how bright a specific location is. It is measured in Lux (Lx) or foot-candles (FC).
A lux meter, also called an illuminance meter, is a device used to measure how bright a place actually is. A lux light meter turns subjective impressions like “too dark” or “too bright” into objective, quantifiable data in lux. These measurements provide reliable reference values for lighting design, adjustment, and evaluation, helping ensure appropriate lighting levels in different environments.
How Does a Lux Meter Work
Working principle of a conventional lux meter: A standard lux meter uses a dedicated V(λ) correction filter to simulate the spectral response of the human eye. The filtered light is detected by a sensor and converted into an analog electrical signal, which is then processed by an analog-to-digital (A/D) converter to produce illuminance data in lux. The measurement accuracy of a conventional lux meter largely depends on how well the V(λ) filter matches the standard photopic vision curve. In addition, the filter may age over time, leading to reduced accuracy. Therefore, this type of lux light meter is mainly suitable for basic or rough evaluation of everyday lighting conditions.
Working principle of a spectral lux meter: A spectral lux meter uses optical elements such as diffraction gratings or interference filters to disperse incoming light into a continuous spectrum ranging from violet to red. The sensor captures light intensity at different wavelengths and converts it into an array of electrical signals. After analog-to-digital conversion and advanced spectral correction, an accurate spectral power distribution (SPD) curve is reconstructed. Based on the CIE photopic vision function V(λ), the system then calculates illuminance along with multiple additional parameters, including correlated color temperature (CCT), color rendering index (CRI), blue light hazard ratio, and PPFD. Compared with a standard digital lux light meter, a spectral lux meter enables a more comprehensive and in-depth analysis of lighting environments.
Differences Between Lux Meters and Other Light-Measuring Instruments
Lux meters, luminance meters, and light meters are all light-measurement instruments, and their names can be confusing at times, especially light meter vs lux meter. However, their measurement targets and application scenarios are fundamentally different.
A lux meter (illuminance meter) measures how much light falls onto a surface.
A luminance meter measures the brightness of light emitted from a surface, such as a display.
A light meter is a general term for light-measuring devices and may occasionally be used as a lux meter or luminance meter. Today, a light meter most commonly refers to a photographic light meter, which is used to determine proper camera exposure settings.
| Instrument Name | Lux Meter | Luminance Meter | Light Meter |
|---|---|---|---|
| Measurement Target | Incident light (light falling onto an object surface) | Self-emitted light (light coming from a screen) | Light intensity used to calculate photographic exposure |
| Core Question | “How bright is the ambient light at this location?” | “How bright does this screen appear?” | “What camera settings should be used for this shot?” |
| Measurement Method | The sensor is placed at the measurement position (e.g., on a desk surface) to capture the total light arriving from all directions. | The sensor is placed close to or aimed at a specific area of the screen to measure emitted light. | Incident metering: placed at the subject position, facing the camera. Reflected metering: measured from the camera position toward the subject. |
| Main Units | Lux (lx) | Candela per square meter (cd/m²) | Exposure Value (EV), or direct aperture/shutter recommendations |
| Typical Applications | Evaluating whether lighting conditions meet health, safety, or functional standards. Common lux meter applications include office desk lighting checks, light meter for plants and supplemental grow lighting, and road lighting acceptance tests. | Evaluating display brightness and visual quality. Widely used for quality control and calibration of smartphones, TVs, and monitors. | Professional photography, cinematography, and landscape photography, especially in complex lighting conditions or film shooting. |
| Reference Instruments | Linshang LS335 Spectral Illuminance Meter | Linshang LS332 Luminance Meter | ___ |
What Does a Lux Meter Measure
The applications of a lux meter are extremely wide. Almost any industry or scenario that needs to evaluate whether lighting is sufficient or meets standards relies on a lux meter or illuminance meter.
Lighting and Luminaire Testing
A lux meter is used to verify lighting fixture performance and determine whether lamps meet required specifications. It also allows comparison of illumination performance between different luminaires, supporting lighting design and product selection. As a result, the lux meter for LED lights is one of the essential tools in lighting R&D and quality inspection.
Workplace Lighting Assessment
Lighting levels in offices, factories, workshops, and corridors are governed by national or international safety standards. Appropriate illuminance must be provided according to task precision to reduce visual fatigue, improve concentration, and enhance overall work efficiency. In such scenarios, a digital lux light meter provides objective and reliable data for compliance checks.
Road and Outdoor Lighting Inspection
Lighting conditions on roads, in tunnels, and in parking areas are closely linked to public safety. These environments must meet minimum illuminance requirements defined by safety standards and be regularly monitored. A lux meter application in this field includes tracking illuminance degradation caused by lamp aging, helping prevent traffic accidents through proper maintenance.
Indoor Environmental Lighting Evaluation
In indoor spaces such as shopping malls and libraries, a lux meter is used to measure illuminance, color temperature, and color rendering index. These measurements help assess whether the lighting environment attracts customers, enhances product presentation, reduces eye strain, and improves reading comfort and focus.
Plant Growth Lighting Measurement
Lux meters such as the LS335 can also function as a light meter for plants. They are capable of measuring parameters including PPFD, YPFD, chlorophyll A/B, temperature, and humidity, enabling a comprehensive evaluation of plant growth conditions. This helps determine whether supplemental grow lights provide appropriate intensity and supports optimal lighting layout for plant cultivation.
Lux Meter Related Standards
ISO/CIE 19476:2014 Characterization of the performance of illuminance meters and luminance meters
EN 12464-1:2021 Light and lighting - Lighting of work places - Part 1: Indoor work places
ISO 8995-1:2002(CIE S 008/E:2001) Lighting of work places - Part 1: Indoor
CIE 13.3-1995 Method of measuring and specifying colour rendering properties of light sources
IEC 62471:2006 Photobiological safety of lamps and lamp systems
IEEE Std 1789-2015 IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers
IEC 60598-1 Luminaires - Part 1:General requirements and tests
IEC 63403-1:2024 Horticultural lighting - LED packages for horticultural lighting
How to Choose the Right Lux Meter
The first factor to consider is the measurement range, which determines whether the instrument is capable of measuring your lighting conditions at all. The selected lux meter must cover the expected illuminance range. This is especially important when measuring high-intensity lighting or powerful LED fixtures, where a wide-range lux light meter is required.
Measurement accuracy is another critical parameter, as it directly affects whether the results are reliable. Users should be cautious of exaggerated specifications from some manufacturers. It is recommended to choose a digital lux light meter that has been verified by an authorized metrology or calibration institute, ensuring accurate and trustworthy measurement data.
If your application goes beyond basic illuminance measurement—such as determining whether a lamp is a full-spectrum light source or evaluating blue-light protection—a spectral lux meter with spectral distribution graphs is the better choice.
Also consider if you need additional features like smartphone/computer connectivity for storing, transferring, and sharing data. These features can significantly improve efficiency in professional lux meter applications.
Price is another important consideration. After confirming that the lux meter meets your functional requirements, compare different brands and models in terms of pricing, as well as pre-sales and after-sales service. This approach helps you select a cost-effective lux meter while keeping procurement costs under control.
Advantages of the Linshang LS335 Spectral Illuminance Meter
The LS335 features a 3.5-inch full-color touchscreen, making operation intuitive and user-friendly. Measurement results are displayed clearly, allowing users to read data at a glance.
It offers both normal illuminance mode and plant lighting mode, enabling the measurement of illuminance, spectral distribution curve, correlated color temperature (CCT), color rendering index (CRI), color tolerance, blue light hazard ratio, flicker, PPFD, YPFD, and more. This makes the LS335 a powerful lux meter for comprehensive lighting evaluation across different applications.
The LS335 spectral lux meter provides an ultra-wide measurement range of up to 1,000,000 lux, ensuring accurate results for both high-intensity lighting and low-light environments. It is well suited as a lux meter for LED lights as well as for general lighting assessments.
With high measurement accuracy, the instrument can be certified by national authoritative metrology institutes, ensuring reliable and trustworthy data—an essential requirement for professional lux meter applications.
LS335 Spectral Illuminance Meter supports connection to a computer, allowing users to store, manage, and share illuminance measurement records. This functionality makes it easy to analyze how lighting levels change over time.
Linshang is dedicated to developing high-quality, cost-effective light measurement instruments. With products used in over 100 countries worldwide, the brand has earned broad global recognition. A professional customer support team is available to assist with both pre-sales and after-sales inquiries at any time.
Linshang Illuminance & Luminance Meters
Dual modes: normal illuminance mode and plant lighting mode
Multi-parameter measurement including illuminance, spectral curve, CCT, flicker, PPFD, and more
Ultra-wide measurement range up to 1,000,000 lux, suitable for demanding lux meter applications
Measures illuminance, spectral curve, CCT, flicker, CRI, PPFD, and other key parameters
1,000,000 lux ultra-wide range, ideal as a professional digital lux light meter
High precision, pass authoritative metrology inspection
Simultaneous measurement of visible light illuminance and UV irradiance
Measurement ranges up to 1,000,000 lux and 200,000 μW/cm²
Designed for UV inspection lamp testing and industrial applications
Displays spectral curve
Equipped with interchangeable 10 mm and 20 mm measurement apertures
High-precision design delivering accurate and reliable data for professional luminance evaluation
How to Use a Lux Meter
First, select the appropriate measurement mode and unit. Taking the LS335 Spectral Illuminance Meter as an example, it offers both normal illuminance mode and plant lighting mode. In normal mode, users can choose between lux (lx) and foot-candles (fc) as the measurement unit.
Next, determine the measurement location. Place the sensor of the lux meter at the position where you want to know the lighting level. For example, when measuring office lighting, the sensor is typically placed on the work desk; for parking lot measurements, it should be positioned on the ground. If the measurement is subject to specific industry standards or regulations, the procedure must strictly follow the relevant requirements.
After the measurement location is confirmed, place the sensor at the selected point and the instrument will automatically display the measurement result. The LS335 Spectral Illuminance meter allows users to press the power (HOLD) key to freeze the displayed data, so the value remains visible even after the sensor is moved. The measured data can also be saved in the instrument for later review.
If the goal is to evaluate a larger area rather than a single point, multi-point measurement is recommended and the average value should be used. The LS335 Illuminance Meter includes data statistics functions that automatically calculate the maximum, minimum, and average illuminance values, providing a more accurate representation of overall lighting conditions.
Frequently Asked Questions (FAQs) of Lux Meters
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How to properly calibrate a lux meter?
Although a lux meter, like LS335, includes a calibration function, it is mainly intended for use by authorized metrology institutes and is not recommended for individual users. Proper calibration of an illuminance meter requires a standard light source, a specified measurement distance, and controlled environmental conditions. Improper personal calibration may actually increase measurement errors.
If you find that your digital lux light meter is producing inaccurate results, it is recommended to return the instrument to the manufacturer for professional calibration.
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Can a lux meter measure LED lights?
Yes. As long as the light output is stable and the spectrum falls within the visible light range, a lux meter for LED lights can be used. This includes incandescent lamps, fluorescent lamps, standard LED lights, and natural sunlight.
However, light sources with rapid or severe intensity fluctuations, such as stage effect lights or strobe lights, are not suitable for measurement with a lux light meter. For non-visible radiation such as infrared or ultraviolet light, a dedicated UV or irradiance meter should be used instead.
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Are the measurement results of the LS335 Spectral Illuminance Meter accurate?
Yes. The LS335 Spectral Illuminance Meter delivers accurate and reliable measurement results and can be verified by national authoritative metrology institutes, making it suitable for professional and regulated lux meter applications.
Lighting conditions are closely linked to our daily work and life. Too dim or too bright lighting can affect not only our visual comfort but also our health and safety. Using a lux meter provides scientific and precise measurements of illuminance, allowing you to optimize the lighting environment. Properly evaluated and adjusted lighting helps prevent eye strain, maintains productivity, and reduces discomfort or safety risks from glare.
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