PGari Glowee: Mac brightness with window spotlight

MacBook Pro brightness: what the slider keeps back

Short answer: MacBook Pro brightness runs into a software ceiling long before the panel runs out. Apple's own specifications for the 14-inch and 16-inch models with a Liquid Retina XDR display list 1,000 nits sustained and 1,600 nits peak for HDR content, but only 500 nits for everything else on the 2021 and early-2023 machines and 600 nits on the November 2023 ones. Hold F2 until the slider is full and the panel is still running at a fraction of what it can do, because the rest is held in reserve for HDR video. PGari Glowee unlocks part of that reserve for ordinary work: up to 1.5× what the slider allows, either across the whole screen or confined to the window you are actually reading.

This page goes through the settings first, the panel second and the app last, and it says plainly which Macs can go further and which cannot.

Start with macOS, not with an app

Most complaints that a MacBook screen is too dim turn out to be a setting. Four of them are worth ruling out before you install anything.

The brightness keys, in fine steps. F2 raises, F1 lowers. Apple's shortcut list adds a second gear: Option–Shift–Brightness Up or Down adjusts the display brightness in smaller steps, which is what you want when the screen is nearly right.
Automatic brightness. System Settings → Displays → Automatically adjust brightness. The ambient light sensor pulls the screen down in a dim room, and Apple notes that turning auto-brightness off "may affect battery life, energy consumption, and long-term display performance."
The battery settings. System Settings → Battery lists Slightly dim the display on battery under Additional Options: "Conserve energy by dimming the display when your Mac is not plugged in." The same list has Optimize video streaming while on battery, which plays HDR video in SDR to save power.
True Tone and Night Shift. True Tone "uses advanced multichannel sensors to adjust the color and intensity of your display and Touch Bar to match the ambient light." Night Shift warms the colours. Apple says the two can run at the same time, so switch both off for a minute if you want a clean comparison.

If the slider is pinned at the top after all that, you have hit the limit macOS sets, not the limit of the glass.

What your MacBook Pro's panel is rated for

The XDR display is built to show HDR video, and HDR needs headroom: highlights that run several times above the white of a document. To keep that headroom free, macOS caps ordinary content — SDR, in Apple's terms — a long way below the panel's peak.

MacBook Pro 14-inch and 16-inch	SDR, slider at maximum	XDR, sustained full screen	XDR, peak
2021 and early 2023	500 nits	1,000 nits	1,600 nits
November 2023 (M3 generation)	600 nits	1,000 nits	1,600 nits
M4 and M5	up to 1,000 nits (outdoor)	1,000 nits	1,600 nits

Every figure is from Apple's technical specifications for the individual model. The XDR numbers apply to HDR content only.

MacBook Pro brightness compared: the slider maximum of 500, 600 or up to 1,000 nits against the 1,000 nits sustained and 1,600 nits peak of the Liquid Retina XDR panel

Read the first row again. On a 2021 or early-2023 MacBook Pro, a full slider gives you half of what the display sustains and under a third of its peak. That is the whole explanation for a Mac that looks spectacular playing a film and washed out in a spreadsheet on a patio in July. On the M4 and M5 models Apple specifies up to 1,000 nits for ordinary content, but qualifies it as outdoor: it is a bright-light behaviour, not a new everyday ceiling you can hold indoors.

How to get more MacBook Pro brightness than the slider allows

The reserve is reachable because macOS hands it to apps as extended dynamic range — EDR. An app is allowed to switch the display into HDR mode and then rescale what is drawn on it. Two techniques do that, and on screen they are easy to tell apart.

Painting a layer. A bright white sheet is drawn over the screen. It is easy to build, and it flattens contrast and drains colour, because you are reading through the sheet.

Asking the panel. The picture is left alone and the display is asked for more light. That is what PGari Glowee does: it drives the XDR panel into HDR mode and scales the display's gamma table linearly. Dark grey and white climb by the same factor, so nothing in the image is crushed or clipped. In the developer's own words there is "no tone-mapping change, no color shift, no white layer on top." Colour work stays where you set it.

Three levels, each a fixed multiplier on the gamma table, inside whatever headroom the display has at that moment:

Level	Gamma factor (slider maximum = 1.00)
Low	1.20×
Medium	1.38×
Max	1.50×

The sun in the menu bar sets the level, and ⌃ ⌥ ⌘ G does the same job without leaving the app you are in.

Light the window you are in, not the whole desk

More light everywhere is also more light on the things you are not reading. Glowee's Boost Area decides where it goes:

Whole Screen lifts the entire display.
Active Window lifts only the window you are working in, and the light moves when you switch windows.
Pinned holds the light on one window while you work around it.

Outdoors with a document open, Active Window is usually the better answer: the page gets the panel's reserve and the rest of the desktop stays where it was.

When macOS resets the display

Night Shift, True Tone and waking from sleep can all throw the display back to its defaults. Glowee watches for that and puts your level back within two seconds; after sleep it re-attaches to each display at the level you left it on.

Which Macs can be boosted, and which cannot

This is a question about the display, not about the app.

Can be boosted — displays with EDR headroom:

MacBook Pro 14-inch and 16-inch, 2021 and later, with Liquid Retina XDR
Apple Pro Display XDR
Other EDR-capable displays. Every connected EDR display is lifted at the same time, so an external XDR panel beside the built-in one rises with it.

Cannot be boosted: the MacBook Air, and any Mac whose display has no EDR headroom. On those the slider's maximum is all the light there is, and no app changes that — a pale layer over the picture is not extra brightness. What helps there is the settings in the first section, and, if the real trouble is a crowded screen rather than a dark one, turning down the windows you are not using, which works on any display.

The price of the extra light

Running a display brighter uses more power and generates more heat, exactly as raising the built-in slider does. Switch the boost off when you come back inside; the shortcut exists for that, one chord on and one chord off.

Worth knowing before your next call: the brightness boost is left out of screenshots and screen recordings, so a recording made on a boosted screen looks perfectly normal to whoever watches it. If the point is to show your audience where to look, that is a different feature — Spotlight dims everything except your window, and it is captured.

MacBook Pro brightness: the questions people ask

Can I make my MacBook screen even brighter?

Yes, if it is a MacBook Pro with a Liquid Retina XDR display. The slider stops at the SDR limit; the HDR headroom above it is still there, and an app can hand it to ordinary content — Glowee by up to 1.5×. On a MacBook Air the answer is no, because the slider's top end is everything the panel has.

I mostly need it outdoors. Does that change the answer?

It changes which model you have to care about. Apple specifies up to 1,000 nits of SDR brightness for the M4 and M5 MacBook Pro, and marks it as an outdoor figure; the 2021 to 2023 models are specified at 500 or 600 nits whatever the light. On an older machine outdoors, the headroom is the only place left to go.

Why is my Mac screen so dark at full brightness?

Usually automatic brightness reading a dim room, or the battery setting that dims the display when you are unplugged, or a comparison against HDR video, which macOS allows to be far brighter than a document on the same panel: 1,600 nits at the top against 500 or 600 for the document itself.

How bright is 1,600 nits?

One nit is one candela per square metre — the unit Apple states these figures in. Apple specifies 1,600 nits as an HDR peak, not as a full white screen; the sustained full-screen figure is 1,000 nits. Against a 2021 MacBook Pro at a full slider, where Apple specifies 500 nits, a peak highlight is roughly three times brighter.

Can you adjust the brightness while HDR content is playing?

Yes. The brightness keys keep working, and the HDR highlights stay brighter than the rest of the screen while they do.

How do I stop the screen dimming on its own?

Three documented settings. Automatically adjust brightness in System Settings → Displays, Slightly dim the display on battery under Additional Options in System Settings → Battery, and, if the screen goes dark after a period of no input, the Turn display off … when inactive settings in System Settings → Lock Screen.

Does this change how colours look?

Not with the panel method. The gamma table is scaled linearly and tone mapping is left alone, so the colours stay where they were and only the amount of light changes.

Is there a free way to try it?

Glowee works fully for seven days with no account and no card. After that it is a one-time purchase — one Mac, or three Macs on one key, with a 30-day refund.

Put it on your own screen

Glowee is a single menu bar app: under 2 MB, macOS 13 or later, one universal build for Apple silicon and Intel. Nothing is added to the system — no kernel extensions, no background helpers — and quitting it hands the display straight back to macOS.

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