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Search our list of questions first, and if you don't find what you need, leave a comment below.
- 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.
- 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.
- f.lux is transitioning a few hours early (or late) and I've set my location properly. What do I do?
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).
- 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. The previous version ignored it. If you don't like your profile, you can change it in Control Panel -> Color Management. We recommend finding a profile that displays accurate colors (or one you like) rather than reverting f.lux to an older 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.
- My cursor is blue on Windows. Why?
This happens when your videocard displays uses a "hardware cursor". Some users have reported that enabling Mouse Trails using a special value in the registry will make the cursor draw in software. See this post on StackExchange for more info.
- 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 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.
- What are the Mac/iOS presets in Kelvin?
- 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 PC presets in Kelvin?
Warm Incandescent: 2300K
- 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 Extras 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.
- 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.
- F.lux makes my mouse stutter, makes my computer slow, and doesn't seem to change my colors at all.
Special note: really, if you downloaded your Radeon driver before November, 2011, you have to update it for good performance with f.lux (get Catalyst 11.10 or later).
Most problems like this can be fixed by updating your video drivers.
Try one of these links: NVIDIA drivers,
- 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 running 10.8.2 flashes blue when I run Chrome (or really any time my Hybrid graphics card switches.) Sometimes f.lux doesn't work at all. Is f.lux doing this?
We think it's not related (we fixed all these bugs.) This problem seems to be reported by people who don't run f.lux at all.
One workaround is to download gfxCardStatus and use only one of the two video cards, discrete or integrated (whichever works better with f.lux).
- 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 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?
DisplayLink has no support for color calibration, so f.lux can't make changes to DisplayLink monitors. Unfortunately, you can only use f.lux today on displays that are directly connected to your computer. (e.g., it usually won't work over remote desktop either.)
- 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 post a comment 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 post a note in the comments section 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.
Because f.lux runs automatically as a background process, and due to the low-level access needed to change your colors correctly, we cannot currently create an app that Apple will approve. We are hopeful that we will get support from Apple in the future as more people come to know about f.lux and love its benefits.
- When is the Android verson coming out?
We have a version internally (it looks beautiful!) but it requires a very complicated installation process. We are working to simplify this and ship f.lux to the Android OS as soon as possible.
- Plenty of things already change the brightness of my screen. Why is this different?
f.lux changes the color temperature of your display. Natural light is more blue, while most artificial light (including candlelight) is warmer. Incandescent bulbs, which we're all used to, become more red in tone when you dim them. But newer LEDs and CFLs don't - this includes the backlight on your monitor. If you're a photographer, you've probably dealt with this, since pictures taken inside at night are always much more brown than photos outside.
- Isn't this exactly the same as the Macbook ambient light sensor?
No, though they do work together nicely. The ambient light sensor measures the brightness of the light in your room and adjusts the brightness of your screen based on that. f.lux changes the color of your screen and warms it up according to the type of light you're using and the time of day.
f.lux doesn't use ambient brightness to adjust colors. You might be in a dark room with very cool light, you wouldn't really want your monitor to look warm, but you would want your display to look dimmer. We've found that when your screen colors match the color of your ambient light correctly, you don't need to adjust monitor brightness as much.
- What is color temperature, exactly?
The term color temperature is a way to numerically describe how much red or blue light is illuminating a room. Color temperature is measured in Kelvins, and is determined by the kind of light you're using.
Confusingly, warmer (more red) light sources are described in lower degrees Kelvin. Compared to indoor lighting, daylight is cool - very blue. A candle is around 1800K, while a sunny day might be 6000K. An overcast day is more blue, so it might be around 7000K.
Most computer monitors display around 6500K. If you are using incandescent task lights behind your computer, those are around 3000K.
- I'm a designer / photographer / artist so I can't use f.lux. This isn't for me!
f.lux was created by people who care a lot about accuracy in colors. We know you want to make sure your colors are perfect so there is an option to disable f.lux for 1 hour at a time (for example, while using Photoshop). This setting returns your screen to its normal settings. In the future we plan to allow automatic disabling of f.lux when you launch certain programs. f.lux is not designed for use during advanced color work, but it's fine for layout or HTML.
Installing & Uninstalling
- 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.
- Go to the Start Menu > Add/Remove Programs > Uninstall f.lux
- 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, and select the type of lighting in your room at night.
- 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.
Any new questions? Leave a comment