What Microsoft says
Windows Central reports that Microsoft described the display as having 5,400 LEDs grouped into 1,344 dimming zones. PCWorld's review also notes that Microsoft supplied the same figures after that review was published. Each zone raises or lowers its backlight according to what is shown in that part of the screen. A bright window on a black background should leave the surrounding dark zones dimmed.
Windows Central's reviewer says they could watch the zones brighten and darken as they dragged a white window across a black background in SDR mode.
Where the dispute started
Notebookcheck's October 19 review said it found no way to activate local dimming. It concluded the panel behaves like a regular IPS screen with a very high black level of 0.61 nits. Its published measurements put contrast at 1,736:1. That is far below the OLED ProArt P16 in the same comparison, which Notebookcheck measured at 0.03 nits black.
The two accounts don't have to be irreconcilable. Microsoft's statement says the hardware has zones and that dimming is on by default. It doesn't explain why Notebookcheck's unit didn't show the behavior. None of the reporting identifies the cause. Possible factors include the settings in use, the HDR state or the firmware revision. All of those are guesses, and nobody has confirmed any of them.
The settings that reportedly matter
According to Windows Central, local dimming depends on Windows configuration. Its reviewer's findings:
- Open Settings > System > Display > Brightness.
- Enable "Change brightness based on content".
- Select the "Enhanced" display profile.
- Turn HDR off for local dimming to work best.
These are one reviewer's test results. Microsoft hasn't published them as a guarantee. The general Surface guidance on content-adaptive brightness does say the feature adjusts the display to what is shown, and that disabling it can reduce battery life.
The HDR trade-off
Windows Central says HDR makes the backlight more noticeable on dark backgrounds, probably because HDR demands more brightness. That largely cures the ghosting and blooming the reviewer saw, but at the cost of local dimming effectiveness. With HDR off, dimming is more effective, but the ghosting and blooming are more visible.
This is an observation from a single device, not a rule for every unit. It does fit the general behavior of Mini LED panels with a modest zone count.
How the zone count compares
Windows Central's reviewer says 1,344 zones is well below what a MacBook Pro offers with the same display technology. Digital Citizen's review similarly says blooming can appear around bright objects on dark backgrounds, and the backlight can take a moment to adjust when bright windows move across dark areas. The reviewer's summary is that the local dimming exists but isn't very good.
Microsoft's published specs
Microsoft's tech specs list:
- a 15-inch PixelSense Ultra touchscreen at 3270 × 2180 (262 PPI) in a 3:2 aspect ratio
- dynamic refresh up to 120Hz
- 1,000 nits typical maximum SDR brightness
- 2,000 nits peak HDR luminance
- a stated contrast ratio of 100,000:1
The spec page also says HDR requires HDR content and must be enabled in device settings. It doesn't mention the LED count or zone count. A 100,000:1 contrast claim also sits awkwardly beside Notebookcheck's measured 1,736:1. Different test conditions could explain the gap, but nothing in the reporting says so.
The October 22 firmware update
Microsoft's update history shows an October 22 release for the Surface Laptop Ultra. It resolves:
- screen flickering
- extended reboot times
- unexpected restarts
It also includes general performance improvements. It doesn't mention local dimming, so owners shouldn't expect it to change dimming behavior. The listed components include:
- Surface TCON firmware 161.32.1.42
- Surface UEFI firmware 7.3.0.0
- Surface Panel Driver V2 3.7.434.0
Microsoft says updates arrive in stages. To check, open the Surface app, expand Help & support and select Check for updates, which opens Windows Update. Restart afterward to finish the install. Microsoft also notes that firmware updates can't be uninstalled or reverted.
What owners should do
- Install the latest Surface updates and restart.
- Confirm "Change brightness based on content" and the Enhanced profile are set.
- Test in SDR first, using a white window on a black background. Watch for the surrounding zones dimming.
- Switch HDR on if blooming and ghosting bother you more than black levels do.
Bottom line
Microsoft says the zones exist, and Windows Central saw them working under specific settings. Notebookcheck couldn't get them working on its review unit. The unresolved question is whether the cause is settings, firmware or a unit-specific problem. Microsoft's published update notes don't promise any improvement to local dimming. Anyone buying at this price for display quality should weigh that, especially against OLED rivals.