f.lux: F.A.Q.

f.lux® software to make your life better

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f.lux support

Search our list of questions first, and if you don't find what you need, head over to our forum.

To install or uninstall f.lux, click here.
Pages displayed by Windows f.lux: Welcome BigUpdate Readme (includes release notes)
Mac quickstart guide here
Mac update history, in AppCast format: macflux.xml

Life and the universe

How do I donate to f.lux?
There's a Paypal link here. Thank you!
How do you guys say "f.lux"?
We say "flux."

f.lux on macOS

I have a newer 2013+ Intel GPU on the Mac, and fullscreen video has blue artifacts. What should I do?
This is a video driver bug and not something we can fix directly. For Chrome, one of our amazing users has made an extension that fixes the issue: VideoFixer for f.lux
I have a newer 2017+ Macbook Pro running High Sierra (10.13), and sometimes white colors turn cyan.
This fix from Apple is only in Mojave, so you'll want to upgrade to 10.14.
On El Capitan, sometimes my screen is tinted during the day, even after quitting f.lux. How do I fix this?
This is no longer happening for most people as of the 37.7 update. In most other cases, the fix is to disable automatic brightness AND reboot. Look at System Preferences > Displays > Color.
How do I turn off the "waking up" notifications?
If they are happening at the wrong time, make sure your wake time is set to the right number in "Preferences". If that's no good either, use the Options menu to turn off "Backwards Alarm Clock".
f.lux on 10.12.4 with Darkroom mode has really bad-looking text
To fix, look in System Preferences > General and uncheck "Use LCD font smoothing when available"
With f.lux on Mac OS El Capitan (10.11), the display is flickering rapidly when the light changes
This is fixed in the later versions of El Capitan. In older ones, El Capitan has a new automatic brightness feature that conflicts with f.lux on some models. You will need to disable "Automatically adjust brightness" in System Preferences, Displays. Some people may have to reboot after this.

f.lux at work

Can I use the free version of f.lux on my work computer?
Yes, with the knowledge and permission of your employer. Our EULA allows users to download and use the software on work machines. Our license is with you, the end user, and not with the company. If you have rights to install it yourself, and your employer approves, we allow it under our personal license.
When should a company obtain a paid license for f.lux?
- Whenever a company recommends f.lux to employees (corporate wellness)
- When an IT department wishes to have control of automatic updates and default settings
- If a company has regulatory requirements (like banks do)
- For any "site license" situation (centrally managing installs for many machines)
In these cases, you should obtain a corporate license here. Currently this build is only available for Windows, and it is covered by a separate Corporate EULA.

f.lux on Windows

How do I find or change settings?
Settings are located in a menu to the left of your system clock. In Windows, this is at the bottom right corner of your screen. On a Mac, it's at the upper right. NOTE: f.lux does not appear in your dock, settings, or your alt-tab menu. Currently settings are only acessible through the taskbar.
Where is "Safe Mode" in f.lux v4?
We built it in! The new build has massively less impact on games and the overall system. If you are a gamer and want less impact while playing games, you can also try Options -> Very Fast transitions.
The Windows f.lux UI now shows everytime I reboot. How do I make it hide again?
We made f.lux do this when you haven't set your location yet. Our automatic setting is pretty bad (especially if you don't live in the USA.) Click on the location button and set things up, and f.lux will auto-hide again.
How do I use the new warmer colors and "Darkroom" mode on Windows?
These features require a small change to your system and a reboot. You can look in the "Lighting at Night" menu and choose "Expand Color Range". f.lux will ask for Administrator access and offer to reboot your PC Now or Later. After your next reboot, you will be able to access more dramatic color changes.
The colors on Windows changed since the f.lux update. How do I go back?
f.lux v3 started reading your system profile and installing it. If you don't like your profile, you can change it in from the Windows Control Panel -> Color Management. We recommend finding a profile that displays accurate colors (or one you like).
f.lux v4 also tries to read properties of your monitor. If you want to try turning that off, look for "Use display data for better color accuracy" in the Options menu.
My cursor is bright white on Windows. How do I fix it?
This happens when your videocard displays uses a "hardware cursor". In f.lux v4, you can look in the "Options" menu and turn on "Software mouse cursor when needed". In the older version, enabling Mouse Trails can help: See this post on StackExchange for more info.
How do I dim my desktop monitor?
In Windows f.lux, use the hotkeys Alt-PgDn and Alt-PgUp. (But if you're on a laptop, you should mostly dim your backlight to keep contrast.)
How do I disable the Windows f.lux hotkeys?
Find the Options menu, and turn them off there.
I changed my system profile on Windows and f.lux is using the old one
Yes you should restart f.lux, or wait 10 minutes for us to read it again.
On Windows XP, the f.lux location dialog does not work. What should I do?
Due to the "Poodle" bug in SSLv3, our server does not allow connections from IE on Windows XP. If you use Chrome or another browser, you can use this map page and paste your location into f.lux instead.

General questions

f.lux is not showing my location very accurately. How do I fix this?
This is by design, and it's to help protect your privacy. We round your location to 0.1 degree. This lets f.lux estimate your sunset timing within about 30 seconds, which is all we need.
f.lux is transitioning a few hours early (or late) and I've set my location properly. What do I do?
Check if your clock is correct using our tool here (it should be within 10 seconds usually). This problem usually means your timezone is set to the wrong one. Double-check by clicking on your system clock. When this happens, usually the local time is set so it looks right, but because it's in the wrong timezone, your computer reports that it's several hours ahead or behind where it actually is.
I installed this but it looks too pink/orange.
On first use, it can take a while to adjust to the halogen settings. Try adjusting the color temperature sliders under Settings until you find one you like. Start with fluorescent or halogen and change it when your eyes adjust. When you disable f.lux, your screen will return to your normal calibration. We're used to looking at very blue computer screens, so it can seem unnatural at first. Most LCD displays are calibrated to display at 6500K, which has even more blue than noon sunlight (5500K).
One of my monitors is flickering - it shows white and then orange quite frequently. What should I do?
(This answer is PC and Mac when used with non-Apple monitors) Look in the On-Screen Display (OSD) and see if you can turn off DDC/CI (the monitor configuration protocol). Some older monitors did not handle color changes well and would reset to white before accepting new settings. This is fine if you change settings once a month, but not so good if you do it more often like f.lux does.
When I scroll text with f.lux on, I see a brief red afterimage. Why?
LCDs are faster at doing "gray to gray" color changes than "black to white", and if you imagine how f.lux is changing your blue channel, the transitions that used to be black-to-white are now black-to-gray.
But what's making this worse these days is a number of GPUs and displays are using a technology called Response-Time-Compensation or "Overdrive" to improve the speed of these gray transitions even more (without improving the speed for black to white much at all). Now, the red channel is noticeably "slower" than the blue (because f.lux has made the blue channel faster). So as you scroll black text, you might see some red afterimages on these displays or GPUs.
Our recommendation: turn off overdrive (or reduce the amount of it) using your driver or on-screen-display.
What is the right color setting for me?
You're at the right color when your monitor screen color looks like the pages of a book under your room lights. We're all used to monitors giving off a 6500K glow, which is even bluer than sunlight. If the default settings of f.lux feel too extreme to you, try setting it to fluorescent, and once your eyes adjust, set it to a warmer temperature. Some studies indicate blue light is beneficial during the day, but late at night it can negatively affect your sleep pattern. Our unofficial study indicates that f.lux makes your computer look nicer in a dark room.
This changes too fast, it always shocks me.
The f.lux transition can be CPU intensive, so f.lux tries to be polite about it. To make it slow, you can use the special 1-hour slow transition option under settings instead.
I work nights. How should I use f.lux?
Our best advice is to set your wake time a few hours early.
How long is Movie Mode and what does it do?
It's 2½ hours. We designed Movie Mode to preserve sky colors and shadow detail, while still providing a warmer color tone. It's not perfect on either count, but it strikes a balance.
What are the presets in Kelvin?
Ember: 1200K
Candle: 1900K
Warm Incandescent: 2300K
Incandescent: 2700K
Halogen: 3400K
Fluorescent: 4200K
Sunlight: 5500K

How do I download the old version?
Try flux-setup3.exe. We do not recommend using v3, as it has signficantly more performance impact on the system. Most people can find find advice here that will make v4 better for their needs.

Troubleshooting: Flickering and Tinted screens

f.lux doesn't work on Windows 10. Help?
Immediately after upgrading to Windows 10, many machines are using a basic video driver that does not work with f.lux. Windows Update will usually get a better driver (within a day) to a version that works with f.lux. In some cases this does work on its own, so we recommend that you update your drivers with the manufacturer's latest version.
I installed f.lux but I can't see any change.
Is it past your local sunset time? Just wait, and f.lux will kick in at sunset.
Is your location set correctly under Settings?
Check that your night-time settings are not set to Daylight.
I uninstalled f.lux and my computer is still orange, what gives?
Some users have encountered a problem where f.lux is no longer running but the screen still appears tinted. If you have checked the Processes tab in Task Manager and there is no f.lux process present, this means another program has absorbed the f.lux color profile. The workaround to restore your screen to its normal profile is as follows: Reinstall f.lux. In the Settings Menu, set both the Night and Daytime sliders to daylight. After 24 hours, any other programs should have re-absorbed the new profile, and you may uninstall f.lux with no more changed colors.
My Lenovo laptop is still tinted after uninstalling f.lux.
Disable the "Lenovo Vantage Eye Care Mode".
My AMD Vega does not change colors at all.
Try to upgrade to a driver version 19.9.1 or later.
My Windows 10 computer flickers at sunset.
Disable Windows Night Light.
F.lux has problems after a Windows Update.
Most problems like this can be fixed by updating your video drivers.
Try one of these links: NVIDIA drivers, AMD Radeon drivers, Intel drivers.
My NVIDIA GPU just stopped working with f.lux. What to do? (2020-2021 drivers)

Please disable "override to reference mode" in the NVIDIA Control Panel. This option appears to be turning on by itself for some people.
Uh oh, my Surface Pro 3 is freezing! (or my Intel-based laptop is slow with f.lux).

Early-2014 Intel HD Windows 8.1 drivers have some bugs that give problems with f.lux, and you may not have the latest one (Surface Pro 3 does not as of September 2014). To make sure you have the latest:
1. Run Device Manager and navigate to Display Adapters : Intel HD Graphics Family. Pick the "Driver" Tab.
2. Check which version you have. If it's less than 10.18.10.3907, you'll want to update (the early-2014 drivers that end with "3412" up to "3621" can cause slowdowns and crashes with f.lux).
3. Download a new intel driver here: Intel HD drivers
  If using a "standard" Intel video card, just get the EXE and install it. You're done!
  If using a Surface Pro 3 or "customized" OEM driver, pick the ZIP download so we can force the install.
4. If you picked the ZIP, unzip it and then:
  1. Back in Device Manager, click "Update Driver" and "Browse my computer..."
  2. Choose the Downloads folder and the zip folder you just extracted.
  3. If Windows refuses this new driver, you should Uninstall and Delete the existing driver and start again from step #1. Windows will use its basic driver in the interim (you won't be without video.)
Ok, but CCC.exe on my AMD Radeon card is still using 1% CPU all the time, and I don't want that.

The Catalyst Control Center is an optional component that can be uninstalled, and you might consider doing this if you're not frequently adjusting your settings for gaming or other reasons. Use Add/Remove Programs, and choose "AMD Catalyst Install Manager" to proceed.
Do not uninstall the Install Manager, but instead use it to uninstall Catalyst Control Center. In our test, this didn't even require a reboot. Also, leave a note on this page (with the driver version) so we can report it to AMD.
My Macbook Pro is having trouble with f.lux, and it flashes sometimes.
On dual-GPU machines we write an ICC profile in order to make the "switch" between video cards more seamless. In some older machines, and every so often, this doesn't work so well. To read about how this system works and turn it off if you want, check out our description here:
Notes about f.lux changes to ICC profiles.
If your Macbook is crashing due to switching between cards, or just to understand when it happens, a really great workaround is to download gfxCardStatus and use only one of the two video cards.
My computer flickers when I use Parallels. What should I do?
You can disable "use Windows gamma settings", and directions are in this post.
I use Shades on my Mac, and f.lux is fighting with it.
Users have reported flashing and flickering when using these together. We recommend you only use one of these programs at a time.
I can't drag the program to the Trash on my Mac.
First quit f.lux from the Settings menu, to the left of your system clock.
I adjusted my color / gamma settings using Windows "Calibrate Display" or NVIDIA's controls and f.lux removes them. Can you keep these settings and use f.lux?
Unfortunately, these systems do not write their settings in a format that f.lux can access (we read VCGT headers only). For better results, we recommend the use of hardware calibrators such as the very good x-rite i1 Display or ColorMunki Display, which write settings in standard ICC files that f.lux can read. If you don't have access to a device like this, you might find a suitable profile for your display online at the TFT Central Monitor Settings Database.
Several people have reported that QuickGamma works well and produces good profiles that f.lux can read.

If you use a Spyder, the software profile loader may cause f.lux to flash periodically. You can disable the Spyder software on startup, and use f.lux instead to load the profile. Also, when you're calibrating a display, you'll want to do the opposite and quit f.lux before you do.
My ASUS laptop is flickering for a minute after startup.
See if you can find an "ASUS Splendid Video Enhancement" feature and uninstall it.
My Sony VAIO is flashing every time it wakes up.
See if you can find a "Color Mode Setting" in Vaio Control Center > Display, and change it to "Do not apply color mode".
I have a new tablet (e.g., a Dell Latitude 10 or an ATIV 500T) that does nothing when I run f.lux. Is there a way to make f.lux work?
These Atom-based machines use the PowerVR SGX545, a mobile-class video card that doesn't currently support color controls. We've had many reports of failures with this chipset, so right now we don't anticipate a better result.
I have a DisplayLink USB monitor adapter. Is there a way to make f.lux work for this display?
Newer DisplayLink adapters have support for color calibration. See our forum post for instructions to enable it. On older adapters, f.lux will emulate this effect using the GPU, which can effect screenshots.
My PC's Anti-Virus program flagged f.lux as malware.
As long as you've downloaded f.lux from this site, you don't have any malware. Every once in a while we get flagged as a potential threat due to the nature of our installer and updater. If this happens to you, please send us a note with your anti-virus program and details and we will contact them for review.
Something else is going wrong with f.lux for Windows
We always recommend updating video drivers as a first line of defense. If you're experiencing flickering or problems, please upgrade your drivers. If that doesn't work, we love to fix bugs. Please send us a note with information on your operating system, video card, and any other information that might be helpful to us.
iOS: Why do I need Location Services enabled?
f.lux uses Location Services to determine the time of your local sunrise and sunset. In the future we will include an option to choose times manually.
Why isn't f.lux available in the Apple App Store? I don't want to / can't jailbreak my device.
We would love to make f.lux available for all iOS devices. To make f.lux work on iOS, we've had to go outside the bounds of what apps are normally allowed to do. Currently, iOS does not allow developers to access the Private APIs we need to make f.lux work on iOS.
Apple values their customers' feedback, so if you have a minute to let them know how f.lux has helped you, and that you'd like to see it available for all iOS devices, send a note at iPhone feedback or iPad feedback.
When is the Android version coming out?
f.lux on Android requires a rooted phone, but it's on the play store here.

f.lux v3 for Windows (2013 version)

What does Safe Mode do on Windows?
Safe Mode does two things: 1. It disables our layered window for compatibility with some older machines. 2. It disables all polling we normally do to ensure that we're the active color profile. Logging in, changing video resolutions, and Administrator (UAC) prompts can all reset f.lux's color changes. With Safe Mode, we do not fix these automatically, in order to minimize the impact we have on the system. If an app resets the colors, you can click on the f.lux icon to have us restore our profile. Transitions (sunrise, sunset) still happen as usual. Use Safe Mode if you think f.lux slows down your computer.
I work nights. How do I flip the day and night settings?
PC f.lux users can unlock the color temperature sliders by holding down the control key while setting your temperature, so night can be swapped with day. We're working on a feature that lets you control time settings more closely.
Since upgrading to Windows 10 Anniversary, my non-DisplayLink screen is flashing a lot, but only when I have my USB monitor or docking station plugged in
Yes, we had a bug that caused this and the main build has been updated (v3.12). Please get an updated build here.

Installing & Uninstalling

Windows Install

Click the f.lux Windows download link.
Run the installer and the f.lux settings page will appear.
Enter your location and select the type of lighting in your room at night.

Windows Uninstall

If you find flux.exe running and do not want it:
Go to the Start Menu > Add/Remove Programs > Uninstall f.lux

Mac Install

Click the f.lux Mac download link.
Click the zip file to expand it
Double click the "Flux" application in your Finder window.
Enter your location, set your wake time, and select the type of lighting in your room at night.

Mac Uninstall

Go to the f.lux Settings panel (to the left of your system clock)
Choose "Quit f.lux"
In Finder, select and delete the f.lux app, and empty the trash.

If you still have a tinted screen, keep going with these instructions until things improve:
In System Preferences > Displays > Color, delete the "f.lux profile" (if f.lux was force-quit)
Reboot the system
Disable automatic brightness, reboot, and turn automatic brightness back on

Linux

Ubuntu-inside.me has written a great guide to using f.lux:
www.ubuntu-inside.me/2009/03/flux-better-lighting-for-your-computer.html

Note: The ubuntu-inside.me site has disappeared but thankfully Archive.org maintains a mirror (linked above) with the original information.

Want to contact us? Email support@justgetflux.com.

Credits

f.lux's map feature uses the "black marble" image from NASA's Goddard Space Flight Center.