You know that feeling when you’re working late and your computer screen starts glaring at you like it’s trying to blind you into submission? The bright, cool light that looks crisp in the afternoon becomes harsh at night. I got tired of that, so I went hunting for something that could make my display much more tolerable—and that’s how I found f.lux.
It doesn’t require changing your habits (like forcing you to stop using the device earlier), buying blue light glasses, or remembering to do anything at all. You install it, set your location (so it knows when the sun rises and sets), and let it do its thing. Since then, I can actually sit at my computer for hours without my eyes begging for mercy.
- OS
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Windows, Linux & Mac
- Pricing model
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Free
f.lux automatically adjusts your screen’s color temperature based on the time of day, reducing blue light and easing eye strain. It shifts your display to warmer tones at night for a more natural, sleep-friendly glow.
f.lux automatically adapts your screen’s color to your lighting
Your PC just got a circadian rhythm
f.lux is a desktop app that automatically adjusts your screen’s color temperature based on the time of day. During daylight hours, it keeps your display bright and cool, similar to natural sunlight. As evening rolls in, the tone shifts to a softer, warmer glow that cuts down on blue light and feels much gentler on your eyes.
The app displays your current solar time and counts down to sunrise or sunset right in its interface. You’ll see information like “The sun has set” and “The sun is up,” along with your circadian response level, which indicates how your screen’s current brightness may affect your sleep readiness. It’s way more insightful than the basic eye comfort modes your devices come with.
You can fine-tune every aspect of how your screen adjusts
Every pixel just the way you like it
f.lux works perfectly fine out of the box, but if you like to tinker, it has a deep level of control. The app comes with a handful of preset color profiles that range from ultra-warm (1200K Ember) to bright and cool (6500K Daylight), with stops like Candle, Incandescent, Halogen, Fluorescent, and Sunlight in between. If you care about color calibration, you will appreciate how this flexibility echoes what you can achieve when you open Windows Color Management.
If you want to go further, the “Custom Colors” menu opens up even more creative options. You can stick with the “Recommended Colors,” switch to the nostalgic “Classic f.lux,” or experiment with quirky modes like “Working Late,” “Far from the Equator,” “Cave Painting,” and “Color Fidelity.” Each one is tuned for a specific vibe or use case, depending on what kind of lighting or mood you’re after.
Then there’s the “Effects and Extra Colors” section, which includes a mix of fun and functional modes. You’ll find options like Movie Mode, Darkroom Mode, Vignette, Grayscale, Use Dark Mode at Sunset, and a handful of eccentric ones such as “Soft White,” “Blue Sky,” “Macular Pigment,” “Emerald City,” “Himalayan Salt Lamp,” and “Civil Twilight.” Despite how playful some of those names sound, they are actually useful for different lighting conditions, whether you’re watching something, trying to stay productive while working late at night, or maintaining color accuracy.
You can also adjust how your screen changes throughout the day using three separate sliders for Daytime, Sunset, and Bedtime. This lets you create a custom transition schedule that matches your routine. The app even includes a “Disable” menu with options to pause f.lux for an hour until sunrise for full-screen apps or when running apps that need perfect color accuracy, like photo editing or color grading in Adobe Lightroom.
For those with smart home setups, f.lux can integrate with connected lighting systems. The “Connected Lighting” tab in the options menu shows integration options for Philips Hue lights, Philips ColorKinetics intelliWhite, YeeLight, and LIFX. You can set it to control these lights based on your screen settings automatically, and there’s even an option to turn off specific lights when the sun is up.
Other useful settings include a “Backwards Alarm Clock” that shows notifications at bedtime, keyboard hotkeys to control f.lux (Alt + End to disable, Alt + PgDn/PgUp to change brightness, Alt + Shift + PgUp/PgDn to change color), and transition speed options—I keep mine on “Slow: Natural Timing” for gradual changes that don’t feel jarring.
It’s a small app that improves your daily routine
What I love most about f.lux is that it doesn’t try to impress you. It’s not flashy, it’s not gamified, and it doesn’t need you to notice it to prove it’s working. It just runs quietly in the background, making your screen experience feel more natural throughout the day.
Even if you already use your operating system’s built-in night light (Windows and macOS both have one), f.lux still feels a step ahead. It offers smoother transitions, more customization, and better control over color temperature. The app has been around since 2009, constantly refined but never bloated with unnecessary features, and the fact that it still holds up says a lot about how well it does its job.