Haze vs. Light Transmittance vs. Transmission: How to Evaluate Transparent Materials and Choose a Haze Meter
Haze, Light Transmittance and Transmission: Differences and Measurement Guide
Haze vs. Light Transmittance vs. Transmission: How to Evaluate Transparent Materials and Choose a Haze Meter
How clear a transparent material looks depends on how much light passes through and whether the transmitted light scatters. Glass, plastic sheets, films, clear packaging, display materials, optical films and liquid samples may be evaluated using haze, transmittance, transmission, clarity or transparency. These terms are related but describe different things. Looking at only one number can lead to surprises: high transmittance with a cloudy appearance, or low haze while images still look soft. This guide explains the differences and how to begin selecting haze and transmittance equipment.
In brief: high transmittance does not guarantee clarity
Transmittance asks how much light passes through a material. Haze describes how much of the transmitted light is scattered. “Transmission” is often used to describe the proportion or performance of light passing through a sample. If the surface or interior scatters light, the material can look cloudy, whitish, misty or unclear even when its overall transmittance is high. For reliable QC, consider haze, transmittance/transmission, sample thickness, surface condition, test standards and customer acceptance requirements together.
What do haze, transmittance and transmission mean?
01 | Haze
The degree of cloudiness or loss of visual clarity caused by light scattering inside or at the surface of a transparent or translucent material. Higher haze generally means a greater proportion of scattered light and a less clear appearance.
02 | Light transmittance
The proportion of light passing through a material. It is commonly used to assess glass, film, plastic sheet, packaging and liquid samples. Higher transmittance means more light passes through, but does not necessarily mean a sharp image.
03 | Transmission
In industry, this term is sometimes used similarly to transmittance to describe the proportion or performance of light passing through a sample. In formal reports, check the instrument definition, standard conditions and reported data fields so different test items are not compared as if they were identical.
Why can materials with similar transparency look different?
When light reaches a transparent material, some may be reflected, some absorbed and some transmitted. Transmitted light can be divided into light that continues close to its original direction (parallel transmission) and light that is redirected (diffuse or scattered transmission). Rough surfaces, microscopic internal structures, uneven filler dispersion, hazy coatings or film processing can increase scattering. The sample may still transmit plenty of light, yet look cloudy or reduce contrast.
A simplified relationship is:
Total transmittance Tt = parallel transmittance Tp + diffuse transmittance Td
Haze = Td / Tt × 100%
Actual measurement depends on the instrument's optical design, the applicable standard and sample conditions. Do not replace a complete QC decision with visual judgment or one number alone.
How do haze, transmittance and transmission compare?
| Measurement | What it measures | Common issue | Related test |
|---|---|---|---|
| Haze | Cloudiness caused by light scattering | Misty, whitish or foggy appearance | Haze meter and transparent-material appearance testing |
| Transmittance | How much light passes through | Whether the material transmits enough light or affects visibility | Transmittance or total luminous transmittance measurement |
| Transmission | Proportion or behavior of light passing through the sample | Differences caused by material thickness, color or structure | Transmission testing |
| Clarity / transparency appearance | Whether images remain clear | High transmittance but unclear object outlines | Advanced appearance analysis, including the YH1810 |
Which materials may need haze and transmittance testing?
Glass and transparent panels
Building glass, protective glass, acrylic and PC sheets can be checked for transmittance, haze and lot-to-lot variation.
Plastic films and optical films
Protective, diffuser, packaging, display and functional films may require evaluation of transmission, scattering and visual clarity.
Clear packaging
Food and cosmetic packaging, label films, bottles and clear boxes can be checked for product presentation and batch consistency.
Liquid samples
Turbidity, color, suspended solids or formulation differences can affect transmission and appearance. Choose the measurement approach based on the sample.
ASTM D1003 and ISO 13468
Requirements may specify ASTM D1003, ISO 13468, a compensation method, sample thickness, measurement conditions or report format. Before choosing a haze meter, confirm which standard the customer requires; whether haze and total luminous transmittance are sufficient; and whether color difference, transmitted color, clarity or data export is also needed. These requirements can affect whether to consider the YH40, YH1100, YH1200, YH1600, YH1210, YH1610 or YH1810. Provide the customer specification, test standard and report format before selecting a model. Confirm applicability against the sample, test objective and manufacturer information. For more detail, see the comparison of ASTM D1003, ISO 13468 and ISO 14782.
Initial haze-meter selection
YH40
Handheld checks for on-site patrols, incoming inspection, process sampling and shipment checks when quick haze and transmittance readings are needed.
YH1100 / YH1200
Vertical haze and transmittance measurement. Consider these for stable, controlled measurement and standardized procedures according to ASTM/ISO requirements.
YH1210
Horizontal haze and transmittance measurement. Consider it for flat films, sheets, glass and transparent packaging when transmitted-color or color-difference data are not needed.
YH1600 / YH1610
Measure haze, transmittance and transmitted color. Consider these when CIE Lab, color difference or transmitted-color data are also required.
YH1810
Adds clarity measurement for samples that also require image-clarity analysis.
What should you avoid when testing?
Checking transmittance but ignoring haze: high transmittance only means more light passes through; it does not mean there is no scattering. Clear packaging, film or display material may still look unclear.
Judging transparency by eye alone: lighting, background, viewing angle and sample thickness affect visual judgment. Use fixed measurement conditions and recorded data for acceptance and lot management.
Skipping standards and reporting needs: confirm the standard, any compensation method, sample dimensions and data-export requirements before selecting equipment.
Frequently asked questions
Does lower haze always mean higher transmittance?
No. Haze and transmittance are related but different. Haze concerns the proportion of scattered light; transmittance concerns the amount of light passing through. A sample can transmit plenty of light and still look cloudy because scattering is high.
Are transmittance and transmission the same?
They may be used interchangeably in some workplaces, but formal tests and reports should follow the instrument definition, standard conditions and data fields. Confirm whether the customer means transmittance, total luminous transmittance, transmission or another optical measure.
When should I consider a model such as the YH1810 for clarity?
Consider clarity measurement when you need to know whether images remain clear through the sample, for example with high-transparency packaging, optical films, display materials or R&D samples. Confirm the application and acceptance requirements first.
Can a handheld haze meter replace a vertical or horizontal model?
Not in every case. Handheld models suit quick on-site checks; vertical and horizontal models may better fit fixed conditions, standardized workflows or more complete appearance analysis. Select according to the test purpose, standards and sample.
What information should I provide when requesting a haze meter quote?
Share the sample material, size, thickness, transparency, matte finish or coating, required measurements (haze, transmittance, transmission, color difference or clarity), ASTM/ISO requirements and any data-export or report-format needs.