What is display scaling?
Display scaling enlarges UI elements (text, icons, buttons) by a factor while keeping them sharp. At 200% scaling, everything is twice as large, but you get half the effective screen space. High-DPI displays need scaling because their pixels are too small for comfortable viewing at 100%.
What's the difference between native and effective resolution?
Native resolution is the actual pixel count of your display (e.g., 3840x2160 for 4K). Effective resolution is the screen space you get after scaling—at 200% on 4K, your effective resolution is 1920x1080, meaning UI elements appear as they would on a 1080p screen, but sharper.
Why does 200% scaling look sharper than 150%?
Integer scaling (100%, 200%, 300%) maps perfectly to physical pixels. At 200%, each UI pixel becomes exactly 4 screen pixels (2x2). Non-integer scaling (125%, 150%, 175%) requires interpolation, which can cause slight blur. macOS handles this better than Windows, but 200% is still optimal for sharpness.
What scaling should I use for my display?
It depends on PPI and your preferences:
Under 100 PPI: 100% (typical 24" 1080p)
100-150 PPI: 100-125% (27" 4K, 15" 1080p)
150-220 PPI: 150-200% (MacBook, Surface, high-DPI laptops)
Over 220 PPI: 200%+ (phones, tablets, Pro Display XDR)
Why do apps look blurry on Windows with non-integer scaling?
Many Windows apps don't support per-monitor DPI awareness. Windows must stretch them, causing blur. Solutions: Use 100% or 200% scaling, enable "Fix scaling for apps" in Settings, or check app-specific compatibility settings by right-clicking the exe > Properties > Compatibility.
Is higher PPI always better?
Not necessarily. Higher PPI means sharper text and images, but it requires more scaling, which reduces effective resolution (less workspace). A 27" 4K (163 PPI) at 150% gives you 2560x1440 effective—great balance. A 27" 5K (218 PPI) at 200% gives you the same effective resolution but even sharper.