When testing plastic films with a haze meter, it’s easy to fall into a common misunderstanding: “If the haze in the results is 79%, then transmittance must be 21%, right?”
Wrong. That’s not how optical properties work.
In this blog, we’ll break down the difference between haze and transmittance, explain why high haze doesn’t mean low transmittance, and help you interpret your haze meter results correctly.
What Do Haze and Transmittance Actually Mean?
To understand your haze meter results, it’s important to know what each term represents:
1. Transmittance = Total light that passes through the material – this includes both clear and scattered light.
2. Haze = Haze is the percentage of transmitted light that is scattered—meaning, it doesn’t pass straight through but is diffused in different directions.
The Key Formula:
Haze (%) = (Scattered light / Total transmitted light) × 100
This means haze is a ratio, not a subtraction from 100%. So even if haze is 79%, that doesn’t mean transmittance is 21%. Both values are measured separately.
Key Point:
Even if haze is high, transmittance can also be high if the material doesn’t absorb much light. For example:
• Milky plastic can have high haze (lots of scattering) and high transmittance (light still gets through).
• Dark tinted glass can have low haze (no scattering) but low transmittance (light is absorbed).
Simple Analogy:
Think of shining a flashlight through:
• Clear glass: high transmittance, low haze.
• Frosted glass: high transmittance, high haze.
• Dark sunglasses: low transmittance, low haze.
Conclusion:
Haze and transmittance are related but not opposites.
• Transmittance tells us how much light gets through a material (clear or scattered).
• Haze tells us how much of that light is scattered and causes blurring.
So, a material can have both high haze and high transmittance—like frosted or milky plastic—because light passes through, but not clearly.
Always remember: High haze ≠ Low transmittance, and vice versa.
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