External display text looks blurry

On a Mac, soft text on an external display is usually a mode problem rather than a panel problem. The same nominal resolution can exist twice — once with HiDPI scaling, once at 1:1 — and one of them looks noticeably worse for text.

The same resolution, two modes

This is a real listing from a 32-inch 4K panel (UP32R7-A, DisplayPort) on a Mac, taken with --list-modes:

UP32R7-A  (current 3008 × 1692 · HiDPI · 120 Hz)
native  3840 × 2160
HiDPI   3360 × 1890
native  3360 × 1890
HiDPI   3200 × 1800
native  3200 × 1800
HiDPI   3008 × 1692
native  3008 × 1692
HiDPI   2560 × 1440
native  2560 × 1440

Notice that 3360×1890, 3200×1800, 3008×1692 and 2560×1440 each appear twice. The HiDPI entry renders through a 2× buffer and then scales; the native entry drives the panel at that exact pixel count — a non-integer scale of a 3840×2160 panel, which is what makes text look soft.

What to do

• Prefer the HiDPI entry when you pick a scaled resolution. On our listing that is 3008×1692 · HiDPI rather than 3008×1692 · native. Same desktop size, sharper text.
• If the mode you want is missing from System Settings, it may still exist: macOS hides a lot of them. Our app lists every mode the display actually reports — including the hidden HiDPI variants — and can switch to one (--list-modes and --set-resolution from the terminal, or the display panel in the UI).
• If the panel is genuinely low density, nothing fixes that. A 34-inch 3440×1440 panel is about 110 pixels per inch; a 27-inch 4K is about 163. Text on the former will always look softer at the same desktop size.
• If you need resolutions macOS does not offer at all — custom timings, virtual screens, scaling the panel does not report — use BetterDisplay. That is exactly what it is for, and we do not do it. We say the same thing on our comparison page.

Why we can tell you this specifically

The app already diagnoses this case: when the current mode is 1:1 and a HiDPI variant of the same size is available, it says so and cites the variant. That check exists because running a large panel at 1:1 is a very common way to end up with text you cannot read comfortably — and the fix is usually one mode switch away.

Related

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