Flux Alternatives: More Devices Support

Yes, several flux alternatives support more devices than f.lux itself, including iOS, Android, Windows, macOS, Linux, and even e-readers and smart TVs. While f.lux is available on most major platforms, it lacks native support for iOS (due to Apple restrictions) and has limited Linux options, so alternatives like Iris, Redshift, and built-in OS features fill those gaps.

Formula

This calculator estimates a comfortable color temperature based on how long you have been using the screen and how soon you plan to sleep.

Formula: a = 6500 - (6500 - 3400) × (t / (t + b))

• t = screen time in hours (default 8)
• b = hours until bedtime (default 2)
• a = color temperature in Kelvin (K), from 6500 K (daylight) down to 3400 K (very warm)

The logic: the longer you’ve been on screen and the closer to bedtime, the warmer the display should be. The result is a smooth transition, not a sudden jump.

Worked Example

Using the defaults: t = 8 hours, b = 2 hours.

1. t + b = 8 + 2 = 10
2. t / (t + b) = 8 / 10 = 0.8
3. 6500 – 3400 = 3100
4. 3100 × 0.8 = 2480
5. 6500 – 2480 = 4020 K

So the calculator suggests a color temperature of about 4020 K, and a blue light reduction of (1 – 4020/6500) × 100 ≈ 38%. This is a warm but not extreme setting, typical for evening use.

Why Look for Alternatives?

f.lux was the pioneer in automatic screen color adjustment, but it has limitations:

• iOS: Apple restricts apps from controlling the display color globally, so f.lux works only on jailbroken devices. Apple’s own Night Shift is the replacement.
• Android: f.lux requires root access on most phones; alternatives like Twilight or Blue Light Filter work without root.
• Linux: f.lux is not officially supported; Redshift is the go-to open-source alternative.
• Multiple monitors: Some tools handle multi-monitor setups better than others.

If you use a mix of devices—phone, laptop, desktop, TV—you need a solution that covers all of them, or at least the ones you use most in the evening.

Built-In Options on Windows, macOS, iOS, and Android

Modern operating systems include night light features, which are the easiest alternatives because they are pre-installed and free.

• Windows 10/11: Settings → System → Display → Night light. You can schedule it and adjust the strength.
• macOS: System Settings → Displays → Night Shift. Works with True Tone on supported Macs.
• iOS: Settings → Display & Brightness → Night Shift. Also has True Tone.
• Android: Most phones have a “Night Lightâ€� or “Eye Comfort Shieldâ€� in Display settings. Samsung, Pixel, OnePlus, and others include it.

These built-in tools are reliable and don’t require extra software, but they offer limited customization—usually just a schedule and a warmth slider.

Third-Party Alternatives: Iris, Redshift, and More

When you need more control or support for older devices, third-party tools are the answer.

• Iris (Windows, macOS, Linux): A paid app with advanced features like blue light reduction, PWM dimming (to reduce flicker), and even break reminders. It works on multiple monitors and can be configured per app.
• Redshift (Linux, Windows, macOS): Free and open-source. It adjusts color temperature based on your location and time of day. On Linux it’s the standard choice, but on Windows/macOS it’s less polished.
• Twilight (Android): Free, no root needed. It overlays a red filter, which is effective but can make the screen look very orange.
• Blue Light Filter (Android): Similar to Twilight, with scheduling and intensity control.
• Night Owl (macOS): A free alternative that works on older macOS versions where Night Shift is not available.

For smart TVs and e-readers, options are more limited. Many modern TVs have a “Night Mode� or “Eye Comfort� setting, and e-readers like Kindle have built-in warm light. There is no universal third-party app for these devices.

How to Choose the Right One for You

Consider your devices and your needs:

1. List all devices you use after sunset: phone, laptop, desktop, tablet, TV.
2. Check built-in options first—they are free and usually sufficient for most people.
3. If you need more control (e.g., per-app settings, automatic location-based schedule, or reduce flicker), try Iris or Redshift.
4. For Android without root, Twilight or Blue Light Filter are the easiest.
5. For Linux, Redshift is the most reliable and well-maintained.
6. For older macOS, Night Owl or Iris can fill the gap.

If you are a developer or power user, you might also like GammaStep (Linux) or Darker (Windows), but those are niche.

Common Problems and Misconceptions

One common misconception is that blue light filters are all the same. In reality, they differ in how they adjust color:

• Color temperature shift: This is what f.lux and most tools do—they change the white point to a warmer (more yellow/orange) color.
• Overlay filter: Some Android apps just draw a semi-transparent red/orange layer on top of the screen, which can reduce contrast and make text harder to read.
• Hardware-level adjustment: Built-in OS features often adjust the display’s color profile directly, which is more efficient and looks better.

Another issue is that some tools don’t work well with multiple monitors, especially if they have different color profiles. Iris and Redshift handle this better than most.

If you see “This app cannot run on your device� on iOS, that’s because Apple doesn’t allow it—use Night Shift instead.

Costs and Safety

Most built-in options are free. Redshift is free and open-source. Twilight and Blue Light Filter are free with ads or a small premium fee. Iris has a free version with limited features; the full version is paid, but you can try it before buying.

Safety-wise, these tools are generally safe to use. They do not harm your screen or battery significantly. However, they are not a cure for eye strain or sleep problems—they only reduce one factor. If you have persistent eye discomfort, consult an eye care professional.

Also note: some apps that claim to “protect your eyes� may ask for unnecessary permissions. Stick to well-known apps from official stores.

Frequently Asked Questions

Does f.lux work on iPhone?

No, not without jailbreaking. Apple restricts apps from controlling the display color globally, so f.lux is not available on the App Store. Use the built-in Night Shift feature instead, which does the same thing.

Is Redshift any good on Windows?

Redshift is primarily designed for Linux. On Windows, it works but lacks a graphical interface and some features. For Windows, consider Iris or the built-in Night Light.

Can I use an alternative on my smart TV?

Most smart TVs have a built-in “Eye Comfort� or “Night Mode� setting. There is no universal third-party app for all TVs. Check your TV’s picture settings.

Do blue light filters affect battery life?

Minimally. Changing color temperature does not consume extra battery; in fact, on OLED screens, a warmer (darker) background can save a little battery. Overlay apps that draw an extra layer might use a tiny amount of extra power.

Which is better: f.lux or Iris?

It depends on your needs. f.lux is free and simple, but lacks iOS support and advanced features. Iris offers more control, works on more platforms, and includes features like PWM dimming, but is paid for full functionality.

How do I set up Night Light on Windows 10?

Go to Settings → System → Display → Night light. Toggle it on, and you can schedule it from sunset to sunrise or set custom hours. Use the slider to adjust the warmth.

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in t | Screen time (hours) | h | 8 | 0 | 24
in b | Bedtime (hours from now) | h | 2 | 0 | 24
out a | Optimal color temp | K | 6500 - (6500 - 3400) * (t / (t + b)) | 0
out c | Blue light reduction | % | (1 - (a / 6500)) * 100 | 0