PGari Glowee: Mac brightness with window spotlight

MacBook Pro brightness: the light your panel is holding back

Short answer: the MacBook Pro brightness slider is a limit set by software, and the panel behind it is not out of light. Apple's Singapore specifications for the 14-inch and 16-inch MacBook Pro give the Liquid Retina XDR display 1,000 nits sustained across the full screen and 1,600 nits peak — but those figures are marked "(HDR content only)". For a document, a browser or a spreadsheet, Apple lists 500 nits on the 2021 and early-2023 machines and 600 nits on the November 2023 ones. Hold the brightness key until the slider will not move and roughly half the panel's output is still sitting unused, reserved for video. PGari Glowee hands part of that reserve to ordinary work: up to 1.5× above the slider's ceiling, either everywhere or inside the single window you are typing in.

What follows: the settings to eliminate first, what Apple's numbers actually mean, which Macs can be lifted at all, and what the extra light costs you.

Eliminate macOS before you blame the display

A screen that looks weak at full slider is usually being held down by a setting. Work through these four, in this order, before you look for an app.

  1. The brightness keys — and the finer step most people miss. F2 raises, F1 lowers. Apple's shortcut list adds that holding Option-Shift with them "adjust[s] the display brightness in smaller steps", and that adding Control applies the change to an external display where the display supports it. Useful when the room light changes through the day and each full step is too coarse.
  2. Auto-brightness. System Settings → Displays, then Automatically adjust brightness. The ambient light sensor reads the room and pulls the panel down — which is exactly what happens when you move from a bright window seat to the shaded side of the office. Apple's own caveat before you switch it off: doing so "may affect battery life, energy consumption and long-term display performance".
  3. The battery setting. System Settings → Battery, under Additional Options, carries Slightly dim the display on battery, which Apple explains as "Conserve energy by dimming the display when your Mac is not plugged in". If your laptop spends the day unplugged between meeting rooms, this one alone explains a lot of complaints.
  4. True Tone. Apple describes it as using "advanced multichannel sensors to adjust the colour and intensity of your display and Touch Bar to match the ambient light". Intensity, not only warmth — so switch it off for a minute and compare before you decide the panel is at fault.

Slider at the top and still not enough? Then you have met the ceiling macOS imposes, not the ceiling of the hardware.

Why full MacBook Pro brightness is not the panel's maximum

The Liquid Retina XDR display exists to show HDR video, and HDR only works if there is headroom: highlights several times hotter than the white of a page. macOS keeps that headroom in reserve by holding ordinary content — Apple's term is SDR — a long way under what the panel can emit.

MacBook Pro 14″ and 16″ 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) 600 nits 1,000 nits 1,600 nits
M4 and M5 up to 1,000 nits outdoors 1,000 nits 1,600 nits

Taken from Apple's Singapore technical specifications for each model. Both XDR columns are labelled for HDR content only.

Chart of MacBook Pro brightness: the slider's ceiling of 500, 600 or up to 1,000 nits beside the XDR panel's 1,000 nits sustained and 1,600 nits peak

Look at the first row for a moment. A full slider on a 2021 or early-2023 machine gives you half of what the panel can sustain and under a third of what it can peak at. On the November 2023 models the same arithmetic lands on 60% and a little over a third. That gap is the whole reason the same laptop can look spectacular playing a film and washed out in a spreadsheet at a table by a glass wall at two in the afternoon. On the M4 and M5 machines Apple quotes up to 1,000 nits for ordinary content, but qualifies it as outdoor brightness.

Two ways an app adds light, and only one leaves the colours alone

The reserve is reachable at all because macOS offers it to apps as extended dynamic range (EDR). An app can hold the display in HDR mode and then change what is drawn on it. There are two approaches and they do not look the same.

The overlay approach lays a pale layer on top of the picture. It is the easy one to build, and you end up reading through a sheet of white: contrast collapses and colours turn chalky.

The panel approach does not touch the picture. It asks the display for more light. That is PGari Glowee's method: it drives the XDR panel into HDR mode and scales the display's gamma table linearly, so every shade climbs by the same proportion. Nothing is re-mapped, nothing is tinted, nothing is laid over the top — photographs and design files keep the colours you gave them.

Three levels, each multiplying the gamma table by a fixed amount, limited by whatever headroom the panel has spare at that moment:

Level Gamma factor, counting the slider's maximum as 1.00
Low 1.20×
Medium 1.38×
Max 1.50×

Switch it on from the sun in the menu bar, or press ⌃ ⌥ ⌘ G without leaving whatever you are working in.

Aim the light at one window

More brightness everywhere is also more brightness on the half of the screen you are ignoring. Boost Area is the setting that aims it:

Reading a long PDF at a window seat while the afternoon sun comes off the block opposite, this is usually the better answer: the page gets the panel's spare light, and the rest of the screen stays exactly as it was.

When macOS resets the display

True Tone, Night Shift and sleep can each knock a display's settings back to where they started. Glowee notices the reset and restores your level within two seconds; after sleep it re-attaches to your displays at the level you left them on.

Which Macs can be lifted, and which cannot

The display decides this, not the app.

Can be lifted — these have EDR headroom:

Cannot be lifted: the MacBook Air, and every other Mac without an XDR panel. On those, the slider's maximum is all the light there is, and software does not change physics. Painting a pale layer over the picture only makes the picture paler. What helps there is the four settings at the top of this page and — if the real complaint is a crowded screen rather than a dark one — turning down the windows you are not working in, which needs no special panel at all.

What the extra light costs

Glowee's own terms are blunt about it: "Running a display brighter uses more power and generates more heat, exactly as raising the built-in brightness slider does." Switch the boost off when you are back at a desk with normal light. That is what the shortcut is there for — one chord on, one chord off.

The boost is also invisible to everybody except you. It is left out of screenshots and screen recordings, so a recording made on a lifted screen looks entirely normal to whoever watches it later. Showing an audience where to look is a separate job, done by a separate feature: Spotlight turns everything but your window down, and that one does survive a capture — which is the entire point of using it while you record the screen.

Questions people ask about MacBook Pro brightness

Can I push a MacBook screen past full brightness?

Yes, if it is a MacBook Pro carrying the Liquid Retina XDR display. The slider halts at the SDR limit and there is HDR headroom above it that an app can open for ordinary content — Glowee by up to 1.5×. On a MacBook Air, no. There the slider's maximum and the panel's maximum are the same number.

Outdoors in the sun, or just a brighter screen indoors?

Both are the same fix on an XDR machine, but the M4 and M5 models are worth a note: Apple already quotes up to 1,000 nits of SDR brightness on those, and specifies it as outdoor brightness. Indoors, under office lighting, the interesting comparison is still the slider against the panel.

Why is my Mac screen still dark at full brightness?

Three usual suspects. Auto-brightness is lowering it to match the room, a battery setting is dimming it while unplugged, or you are comparing it with HDR video, which macOS allows to run far brighter than a document on the very same panel — up to 1,600 nits against 500 or 600.

How bright is 1,600 nits?

One nit equals one candela per square metre. Set against the 500 nits Apple specifies for a 2021 or early-2023 MacBook Pro at full slider, a 1,600-nit highlight is about three times as bright. That number describes an HDR highlight rather than a full white screen; across the whole screen at once Apple lists 1,000 nits.

Can the brightness still be adjusted while HDR is playing?

Yes. The brightness keys keep working while HDR content is playing, and the HDR highlights stay brighter than everything else on the screen.

Are you trying to turn off auto-brightness?

System Settings → Displays, switch off Automatically adjust brightness. Read Apple's warning first: it "may affect battery life, energy consumption and long-term display performance". If the screen only goes dark after a spell without typing, that is System Settings → Lock Screen instead, where the two Turn display off … when inactive settings each take a duration.

Does this change the colours?

Not with the panel approach. The gamma table is scaled linearly and tone mapping is left alone, so the colours stay where you put them and only the light output moves.

Can I try it without paying first?

Seven days, every feature unlocked, no account and no card. After that Glowee is a one-off purchase — one Mac, or three Macs on one key — with 30 days to ask for your money back.

Try it on your own screen

PGari Glowee is one menu bar app of under 2 MB. It needs macOS 13 or later and runs as a single universal build on Apple silicon and on Intel. It puts nothing into the system — no kernel extension, no background helper — and the moment you quit it, the display is back where macOS had it.

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