What is PWM, Why is it Important, and Why Did We Add This Test to Our Reviews?

LaptopMedia.com Highlights What is PWM, Why is it Important, and Why Did We Add This Test to Our Reviews?

From: Simeon Nikolov 18 November 2024 / 18:00 | 26

Published: July 2015
Updated: November 2024

Perhaps you’ve noticed that the LaptopMedia team has started testing every laptop for Pulse-Width Modulation. PWM is used to regulate the brightness of LCD and LED displays. How does that concern us?

The pulsations can be bad for your health and more specifically for the users’ eyesight. They can lead to migraines, headaches, or other forms of discomfort after long-term usage. In many cases, those pulsations have a frequency somewhere around 240Hz. They cause multiple contractions and expansions of the pupils, which bears down negatively on your health. They are especially harmful in models with LED backlight because the colors of the emitted light are not as inert as the colors of the CCFL backlight and so they reach high amplitudes and rapid luminance changes.

Basically, the problem comes from the flickering of the light rather than from the crystals in LCD monitors.

➡️ Top Laptop PWM Ranking (Rated by negative impact on eyesight) ⬅️

Pulse Width Modulation (PWM) is an easy way to control monitor brightness. When you lower the brightness, the light intensity of the backlight is not lowered, but instead turned off and on by the electronics with a frequency indistinguishable by the human eye. In these light impulses, the light/no-light time ratio varies, while brightness remains unchanged, which is harmful to your eyes.

If there is PWM, it is better to have a high frequency of around 20,000 times per second instead of, say, 200. This is noticeable at different brightness reduction levels for different monitors. It is noticeable to a higher degree in LED than in CCFL backlights due to the former’s lower afterglow and higher nominal diode brightness.

Below are the waveforms of 4 displays.

1️⃣ The first one doesn’t emit pulse-width modulation, which provides the option to work for extended periods of time.
2️⃣ The second is a classic PWM. Its aggressive pulsations at a low frequency put extra pressure on the eyes and brain.
3️⃣ The third also emits PWM, but it has an extremely high frequency, which is considered to be less harmful.
4️⃣ The fourth one doesn’t flicker unless the brightness is <25%, so it is eye-friendly in practically every normal usage mode.

PWM

✅ OUR SOLUTION

To minimize the harmful effects of devices we’ve brought into our homes and can’t part with. While we might not stop using them, our lab has enabled us to deeply investigate and develop a suitable solution for our users.

From now on, every notebook entering LaptopMedia’s lab will receive a custom package of three profiles: “Design and Office”, “Gaming and Movies,” and “Health-Guard.” These profiles will be sold digitally at a nominal price. By purchasing these profiles, users obtain a valuable product and support the growth and expansion of our lab, where we conduct specialized research.

Each profile is tailored for each display model.

For PWM-controlled backlights, the profile lets you dim the brightness, ‘closing’ the pixels through a special PWM-Free slider, avoiding PWM. You can also use this slider to dim your screen further in case the brightness of your display is too high, even when you’ve lowered the Windows slider to the minimum.

But the “Health-Guard” profile offers more than just reduced brightness. The Health-Guard profile reduces the white temperature to around 5750-6000 K, while maintaining perceptually accurate colors, and adequate contrast.

Color accuracy is a priority – whites stay white, blues stay blue, etc., avoiding eye-straining reddish tints.

All these features distinguish the “Health-Guard” profile from free “color warming” alternatives.

Here is a comparison of two spectral diagrams from a modern notebook display emitting ‘white’ light. The first one is without a profile, while the second represents the “Health-Guard” profile.

How to Buy?

For every laptop that visits our lab, we create display profiles, which can be found in our detailed reviews. We also have a LaptopMedia Profiles Supported Laptops List page, where you can find all the machines for which we have created profiles over the years.

You could also place an order here but don’t forget to tell us an e-mail with your exact panel model. Scroll down to see where to find it.

In addition to receiving efficient and health-friendly profiles, by buying LaptopMedia's products you also support the development of our labs, where we test devices in order to produce the most objective reviews possible.

Design and Office

The Design and Office profile makes display colors as close to real as possible.
Ideal not only for professionals but also for everyday users, it meets sRGB standards (D65 white point, sRGB gamma) with minimal DeltaE for precise color reproduction on your panel.

$9.99 BUY NOW

Gaming and Movies

Have you ever watched a movie where, during dark scenes, you can barely see anything? Many displays fail to distinguish dark tones properly. Our Gaming and Movies profile enhances low-light performance, like HDR tech, using a gamma curve tailored to human perception — ideal for gamers seeking faster reactions and clearer visuals.

$9.99 BUY NOW

Health-Guard

Our Health-Guard profile protects your eyes by eliminating PWM flickering, reducing strain and fatigue, and minimizing harmful Blue light exposure that can disrupt sleep and health. It uses software dimming and a gamma curve tailored to human perception for comfort and safety during screen use.

$9.99 BUY NOW

Get All The Profiles With 33% Discount!

$19.99 BUY NOW

Where to find my exact panel model?

One of the best ways to do that is with an app like HWINFO – it’s free, and its portable version doesn’t need installation:

Installation and Usage

For easy use and switching between profiles, we developed the LM Profiles 3.0 app. Just download it, then drag and drop the profiles onto the application. That’s it!

You can now effortlessly switch between modes and take advantage of the PWM-free brightness slider when the “Health-Guard” profile is activated (to ensure that PWM is eliminated, make sure the Windows brightness slider is set to maximum).

Have Questions?

Feel free to reach out to us through our Contact Us page.

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Zer0

2 years ago

Well, i’m 100% losing my vision since i got the new laptop (Dell 3580), anything further than 5′ is blurry.

but what’s the solution ? alternative ? i don’t understand the technical side of it. does it mean i’m better off keeping the brightness at 100% ?

Rob

1 year ago

Reply to Zer0

Agreed, a bit more guidance would be helpful! My eyesight is not what it used to be & optician has advised wearing sunglasses in bright light. PWM is rarely or never mentioned in retail site laptop specs. Regarding the ASUS I looked at, if I understand it right, as long as you don’t turn the brightness down too low the PWM is not a worry. So say 75% brightness should be OK but very low settings (say under 40%?) increases the PWM. I really think this & the blue light output levels should be in every spec sheet, instead of… Read more »

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7 months ago

[…] As you’ll probably be spending a lot of time on these two machines knowing that they’re PWM-free is good to know. PWM or Flickering is a known way for screens to adjust their brightness, however, it comes at the cost of tiring your eyes and causing headaches. You can learn more about PWM in our dedicated article. […]