F.lux 4.118

Adjust your display's color temperature based on the time of a day
Tweak the color temperature of a computer's display according to your location and time of a day. Choose from an array of color and temperature values and set modes for various activities, including film watching or a darkroom mode. Get respite for the eyes and reduce the prominence of the white-blue light to sleep better even if you're staying up too late.

The amount and the type of light that your computer screen emits are just as important as the lighting conditions around you. f.lux is a tiny program that customizes the amount, temperature, and brightness of the color of your computer display. Using your current location and your average wake time, it will adapt your screen gradually to the surrounding light according to the actual time of day.

Spending long periods in front of your computer screen is stressful enough for your eyesight to add up eyestrain and other eye problems due to deficient lighting conditions. Computer displays are designed to look great during the day in terms of color and brightness, but they prove to be clearly inadequate at night. f.lux offers you an automated way to match the temperature and brightness of the light your computer display emits to the light around you. To do so, it only needs to know where you are located. With that information, the program knows exactly the time of day you’re sitting in front of your computer and dims or brightens your display accordingly.

Watching your screen colors and temperature change gradually as time flies by is a nice and soothing experience, not to mention the benefits your eyesight draws from it. Regrettably, f.lux can only guess the actual light around you using the current time at your location. The program doesn’t know if that day is darker than usual for that time of the year or if you’re working in a windowless room while the sun shines outside. Luckily, f.lux provides you with a nice collection of presets to fit nearly all possible conditions, not to mention the possibility of tweaking the program’s settings to match your specific requirements. You will find presents to reduce eyestrain, to work until late, to sit in front of your computer while “Far from the Equator”, to “cave paint”, etc. Adjusting the settings yourself, though, requires some knowledge of how light works and how many K degrees are adequate to each situation and how Circadian response works.

Other than that, f.lux is certainly easy to set up and use, and it’ll do most of the hard work of controlling the glow coming from your computer display on its own. This is not a free utility but it isn’t pricey either, so if you happen to find your screen uncomfortable to look at times, f.lux a good option to consider.

Francisco Martínez
Editor rating:

Review summary


  • Automatic light changing according to your location
  • Offers presets for the most light conditions
  • Includes effects and extra colors for specific light conditions
  • Supports hotkeys for the main controls


  • The light around you is based on the time of day only
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