Fix Windows DPI Scaling Problems

Windows DPI scaling was designed for single-monitor setups with a single DPI value. Modern multi-monitor and 4K setups expose several architectural limitations that cause blurry apps, wrong UI sizes and scrambled layouts.

The first thing to check: is your system-wide DPI set to a sensible value? Go to Settings → System → Display → Scale and choose from the recommended values. Stick to multiples of 25% (100%, 125%, 150%, 175%, 200%) — these map cleanly to pixels.

After changing the global scale, sign out and sign back in. Some apps won't pick up the new DPI until their process restarts — a sign-out/sign-in restarts all user-space processes at once.

On multi-monitor setups with different screen sizes, each monitor needs its own DPI value. In Settings → System → Display, click each monitor rectangle individually before changing the Scale slider — the setting applies only to the selected monitor.

Windows applies these per-monitor values correctly for apps that declare Per-Monitor v2 DPI awareness. For older apps, see the per-app override section below.

For apps that still look blurry after setting the correct system DPI, apply a per-app override. Windows has a built-in way to do this, and Display EX automates it.

Built-in Windows method

Right-click the app's .exe → Properties → Compatibility → Change high DPI settings → tick Override high DPI scaling behaviour → set dropdown to Application. Restart the app.

Automated with Display EX

Open Display EX → DPI Overrides → Add app → select the executable. Display EX applies the override automatically on every launch and stores it per display profile — so your 4K profile has different overrides than your laptop profile. See the blurry apps guide for full details.

The hardest case: a 4K monitor at 150% next to a 1080p monitor at 100%. Windows handles this reasonably well for modern apps, but older software and even some current apps fail in two ways:

Problem 1: Blurry when moved

An app moved from the 100% screen to the 150% screen renders blurry because it doesn't re-draw at the new DPI. Fix: use Display EX's Auto re-apply DPI on monitor change setting, which triggers a DPI refresh cycle when a window moves between screens.

Problem 2: Wrong size on secondary monitor

Some apps use the primary monitor's DPI for all windows regardless of which screen they're on. This is an app bug — the only workaround is to set the secondary monitor to the same DPI as the primary, or use a per-app override to force System DPI awareness mode (which at least keeps the app consistently sized, if not per-monitor sharp).

The most persistent scaling problem: driver updates, reboots and monitor reconnections reset per-monitor DPI values back to defaults. Display EX solves this by saving the complete DPI configuration as part of each named profile.

Create a profile once with all your DPI settings correct, set it to Apply on startup, and Display EX re-applies the full configuration — including per-monitor scale values — every time Windows boots. No more hunting through Display Settings after every driver update.

See the multi-monitor guide for a full walkthrough of creating and switching profiles.

DPI resets to 100% after reboot

Create a Display EX profile with the correct DPI settings and enable Apply on startup. Display EX re-applies all display settings including scale values a few seconds after login.

Custom scaling percentage causes blurriness

Non-standard percentages (e.g. 137%, 163%) cause fractional pixel mapping. Stick to 100%, 125%, 150%, 175% or 200%. If none of these feel right, try Display EX's custom scaling tool which uses a different rendering path.

App looks correct on launch but blurry after moving windows

Enable Auto re-apply DPI on monitor change in Display EX settings. This triggers a DPI refresh when a window changes monitors, prompting the app to re-render at the new scale.

Everything looks too small at correct DPI

This means the DPI is set correctly for sharpness but the UI is physically too small for comfortable reading at your viewing distance. Increase the scale one step (e.g. 125% → 150%) and run the sign-out/sign-in cycle again.