The Best F.Lux Settings: Everything You Need to Know

See here what are the best settings for F.lux, how the color settings in F.lux works and how to adjust it to reduce eye strain.

What is it? F.lux is the best program for anyone who works at a computer for long hours, as it helps fight eyestrain by reducing the amount of blue light from the screen, thus protecting your eyes.

But for F.lux to work, you need the correct settings. Three factors will influence the right screen color for you:

  • Your wake-up/sleep habits
  • The time of the day
  • Your room lights

While there are no one-size-fits-all settings for everyone, the app developers claim that the best settings for F.lux are the ones that will have your monitor screen color looking like the pages of a book under your room lights.

If you need specific instructions, keep reading for more detailed guidelines.

(If you didn’t install F.lux, I recommend following the basic setup steps I’ve written in the article on how to always keep night light on. )

F.Lux Recommended Settings – Tips to Choose the Right Screen Color:

Here are some essential tips for adjusting F.lux screen colors:

  • If your eyes get tired quickly when staring at a screen during the daytime, try to set your daytime color value to something below 6500K. I suggest using 5900 K (the same as the Reduce Eyestrain mode); some users prefer warmer colors in the 3500K-4500K range.
  • If you can’t get used to F.lux evening color settings, try to switch the sunset settings from halogen (3400K) to fluorescent (4200K).
  • Adjust your screen color to a warmer tone if you are in a dark room during the daytime. The room light is an essential factor.
  • To disable F.lux when playing games, click on the hamburger icon > disable > disable for fullscreen apps.

As you probably noted, F.lux’s colors are measured in K.

What does the K in F.lux mean?

The K in F.lux means Kelvin, a widely used temperature unit. In F.lux, it refers to color temperature, with lower values relating to warm colors and higher values relating to cold colors.

Below I will tell you the default screen colors in F.lux and what they look like in real life.

Understanding F.lux Color Settings

These are the default color values according to F.lux:

Name in F.LuxColor Temperature (in Kelvin)
Candle (Default for Bedtime)1900K
Dim Incandescent2300K
Halogen (Default for Sunset)3400K
Daylight (Default for Daytime)6500K

This information is very meaningful, but only if you understand what these color temperatures represent in real life.

The color temperature guide from Standard Pro provides some useful examples, which I arranged in the chart below:

ExampleColor Temperature (in Kelvin)
Candle Light1500K
Incandescent Bulb2680K
Sun at sunrise/sunset3200K
Morning or Afternoon Light4200K
Daylight at Noon5500K
Full Sun6500K
Overcast Sky7500K

They also give some examples of the type of light in indoor environments:

  • Living room / Libraries / Bar: 2500-3300 K
  • Kitchen / Warehouse / Store: 3500-4000K
  • Office / Restaurants / Reception: 5000-6500K

I have some tips below if you want some extra tips to get your perfect settings.

(If you want to learn how to change your folders’ background color, check the article I’ve written on it.)

Extra Tips to Adjust F.Lux Screen Colors

Here are some tips to get the best of F.lux:

  1. Reduce Eyestrain Settings
    Make sure to use F.Lux default mode to reduce eye strain. To turn it on, toggle Recommended Colors, in the top right corner of the f.lux interface, to Reduce Eyestrain:
  2. Instantly Preview Your Screen Color on Different Hours of the Day
    To preview how your screen will look at different times of the day, double-click on the color temperature graph in the F.lux main interface:

    If you are unsatisfied with your screen light during a certain time of the day, you can click once on the color temperature graph and manually input the values.
  3. Keeping the Warm Tones in Daytime
    You can keep the night light always on by adjusting your daytime color to a warmer tone:
  4. Adjust your Custom Colors
    If you want to test a different value or set it temporarily, you can adjust it in the color temperature bar on the main screen.

The color you set will be defined as Custom Colors, and you will lose this color if you adjust back to Recommended Colors, Reduce Eyestrain, or another mode.


The best settings for F.lux depends on your waking up/sleeping habits, the time of the day, and the room of your light. The official F.lux website recommends the following rule of thumb: “You’re at the right color when your monitor screen color looks like the pages of a book under your room lights.”

To understand F.lux color settings and how they look in real life, check the tables I prepared in this article.

If your time zone keeps changing back to pacific, I’ve written an article on how to fix windows 10/11 time zone keeps changing to pacific.

To know more amazing software like this, check my personal list of must-have software for Windows.

Laerthe Côrtes

Laerthe Côrtes

My first desktop computer, back in the 1990s, opened a whole new world for me; since then I am a heavy PC user (who will never get used to smartphones.) I worked for five years in the PC software industry, and my favorite version of Windows is still Windows 95.

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