RedDimmer
Go warmer. Then go red.
Move from neutral white to a soft amber or pure red. Warmth and brightness are independent, so you can find your own balance.
Free screen dimmer & blue light filter for macOS
Less glare.More night.
A free screen dimmer for Mac. Lower the brightness below your usual screen settings and shift from everyday white to warm amber or pure red, right from the menu bar.
macOS 13+ · Intel & Apple silicon
RedDimmer
At home in your menu bar
Interactive previewAn illustration; your display may look different.
6500 K to pure red
Software dimming down to 10%
At home in your menu bar
Your screen. Your kind of evening.
Set it once. Let the evening follow.
Choose Day, Evening or Night, customise your presets, and schedule changes around sunset and sunrise or your own fixed times.
Your whole desk. Your choice.
Use individual-display controls and app exceptions to suit your work. Pause the filter when you need original colours, and restore your preferred setup when you are ready.
A quieter screen. A private app.
Your settings stay on your Mac. No account, advertising or app telemetry. Choose a city for sunset scheduling, or give location access only when you want to.
Privacy Policy ↗A free Mac screen dimmer, made for evenings
When the room gets darker,
your screen can follow.
A bright white screen can feel out of place at the end of the day. RedDimmer gives you two simple controls: how bright it looks, and how warm its colours feel.
Use it for late-night reading, a quieter desk, or a MacBook screen that still feels too bright at its lowest setting. You can add software dimming without changing your files, browser theme or the apps you work in.
Go below your usual minimum brightness
Reduce displayed brightness down to 10% with software dimming. It’s useful when the hardware brightness slider alone doesn’t give you the darker screen you want. The percentage is an app setting, not a measured light level.
Choose how far into red you go
Keep a little warmth for everyday reading, move into amber for the evening, or choose a deep red screen tint. Brightness and warmth work independently, so a warmer screen doesn’t have to stay bright.
Let your routine do the adjusting
Customise Day, Evening and Night presets. Use sunset and sunrise, or your own fixed times, to schedule changes. Pause the filter when you need normal colours, then return to your preferred setup.
For your whole desk. Adjust individual connected displays, and add app exceptions for work that needs its original colours. Display support depends on the Mac, monitor and macOS version.
Easy to live with. Menu-bar controls, configurable app shortcuts, optional launch at login and a Restore Colours action. No account or subscription to manage.
A little science behind a softer screen
Your eyes see colour.
Your body clock notices light.
Light does more than help you see. It also gives your body information about the time of day. The light-sensitive pigment melanopsin is especially responsive around 480 nanometres, in the blue part of the visible spectrum, before the eye’s optical filtering is taken into account. Brown et al., 2022 ↗
That is why brightness, colour and timing all matter when thinking about evening light. A warmer, dimmer screen is one adjustable part of your environment. Room lighting, how long you use the screen and when you put it away matter too.
Wavelength, explained
From blue-rich white to warmer light.
Illustrative white referenceWhite example
Give evening a different light setting.
Research-informed lighting recommendations for healthy adults call for brighter days and much lower body-clock-effective light in the hours before sleep. The numbers below describe light reaching the eye, measured as melanopic equivalent daylight illuminance. They are not screen-slider percentages. Read the recommendations ↗
During the day250 luxRecommended daytime minimum
3 hours before bed10 luxRecommended evening maximum
While sleeping1 luxRecommended sleep maximum
Make the screen fit the evening. RedDimmer makes it easy to choose a dimmer, warmer display. Pair it with calmer room lighting and a screen-free end to your day.
Read the evidence
Real studies. Plain explanations.
The research below informs the discussion of light and screen habits. These studies tested their own lighting or screen-use conditions; they did not test RedDimmer.
Evening screen light can change sleep timing.
People reading a light-emitting e-reader before bed took longer to fall asleep and showed later body-clock timing than when reading a printed book. This supports paying attention to evening light; it doesn’t establish a sleep benefit for any particular filter app.
Chang et al. · PNAS ↗A warmer colour alone is not the whole answer.
A trial of 167 young adults found no overall sleep differences between iPhone use with Night Shift, use without it, and no phone use. A colour setting is one tool; it should not be sold as a guaranteed way to improve sleep.
Duraccio et al. · Sleep Health ↗Myopia research is about screen habits.
A review of 45 studies found an association between longer screen time and myopia, mostly in children and young people. Association does not prove cause, and this is not evidence that blue light causes myopia or that a red screen filter prevents it.
Ha et al. · JAMA Network Open ↗Eye-strain claims deserve care.
A Cochrane review of 17 trials found that blue-light-filtering spectacle lenses may not reduce short-term computer eye strain; sleep findings were uncertain. This was research on glasses, not RedDimmer. Our practical promise is control over the appearance of your screen.
Singh et al. · Cochrane ↗A softer screen, at the end of your day.
Choose the brightness and colours that suit your evening. RedDimmer is free.
A few things worth knowing
About dimming, blue light
and your Mac.
What does a Mac screen dimmer actually do?
RedDimmer reduces the brightness of the image your Mac displays using software. That can make the screen look darker than your usual hardware brightness setting alone. The warmth control separately reduces green and blue colour-channel output relative to red. It doesn’t change your documents or the colours stored in image files.
Why use RedDimmer when macOS already has Night Shift?
RedDimmer combines software dimming down to 10%, warm-to-red colour, editable presets, schedules, pauses and individual-display controls. App exceptions pause redness while keeping your chosen dimming level. It gives you a dedicated set of choices in the menu bar. Avoid overlapping colour adjustments if they make the result unpredictable on your Mac.
Does blue light from a screen damage your eyes?
The American Academy of Ophthalmology says there is no scientific evidence that blue light from digital devices damages the eyes. Discomfort after long screen sessions is a separate issue. Take regular breaks, blink and set up your screen sensibly. RedDimmer is a display-preference tool, not treatment for an eye condition. Read the Academy’s explanation ↗
Will a red screen filter prevent myopia or improve my sleep?
RedDimmer has not been clinically tested for either outcome. Screen-time research does not demonstrate that a colour filter prevents myopia. Evening light research gives a reason to consider timing, brightness and colour together, but a warmer screen does not guarantee better sleep. Use the controls for a screen you prefer, alongside sensible screen habits.
What does “0 K” mean in the app?
It is the app’s name for its pure-red setting, not a physical colour temperature. “6500 K” to “0 K” describes the app’s warmth scale. RedDimmer does not turn your monitor into a calibrated, single-wavelength light source or measure its spectrum.
Does it work on MacBooks and external monitors?
RedDimmer requires macOS 13 or later on an Intel or Apple silicon Mac. You can set warmth and software brightness for connected displays individually. Colour support varies by Mac, display and macOS version. If a display does not respond, switch RedDimmer OFF or use Restore Colours, then contact support.
Will other people see my red tint in a screenshot?
The colour tint usually changes how your display looks rather than the screenshot file. Very low brightness and some recording or sharing tools can capture a different result. Check a sample recording or screen share before presenting, and switch RedDimmer OFF when you want normal colours and brightness.
Is RedDimmer really free?
Yes. RedDimmer is a free Mac app, with no account or subscription required. The Mac App Store release is being prepared. The download link will be added here when it is available.
Find your evening fit
Which Mac screen dimmer
is right for you?
Compare RedDimmer with familiar colour filters and monitor tools. See where our free warmth-and-dimming routine fits, and when another app makes more sense.
Best screen dimmers for Mac: our ranking →Automatic colour changes
RedDimmer vs f.lux
Automatic colour routines
Advanced colour preferencesRedDimmer vs Iris
Advanced colour preferences
Open-source screen dimmingRedDimmer vs Dimit
Open-source colour and dimming
External-monitor automationRedDimmer vs Lunar
External-monitor automation
Free monitor brightness controlsRedDimmer vs MonitorControl
Free external-monitor control
A complete display toolkitRedDimmer vs BetterDisplay
Display scaling and advanced tools
The built-in Mac optionRedDimmer vs Night Shift
Built-in warmer colours
A softer screen. Completely free.
RedDimmer is free, with no account or subscription. The Mac App Store release is being prepared. The download link will appear here when it is available.
SupportRedDimmer release coming soon · macOS 13+ · Intel & Apple silicon