Two displays can have the same logical desktop size while rendering a given interface element at different physical sizes. This calculator compares that geometry. It does not decide which monitor is comfortable, prescribe an ideal scaling percentage or model every application’s rendering.
Dual-display resolution and scaling comparer
Compare physical pixel density with a percentage UI-scaling model. Use native pixel dimensions; the result is not an ergonomics or eye-health verdict.
1920 × 1080 at 100% and 3840 × 2160 at 200% have the same modeled logical workspace, while physical pixel density depends on diagonal. All entries are editable examples; no product was measured for this tool.
Enter your setup to see the result.
Your inputs stay in this page. No account connection or automatic storage.
Three quantities to keep separate
Physical pixels per inch are √(horizontal pixels² + vertical pixels²) ÷ diagonal inches. This is the density of the native pixel grid. Percentage scaling does not change that physical density.
In this percentage model, logical dimensions are native pixels divided by scale percent ÷ 100. A 1920 × 1080 display at 100% and a 3840 × 2160 display at 200% both produce a modeled 1920 × 1080 logical workspace. The second panel still has more physical pixels; equal logical workspace is not equal PPI.
For the same logical UI element, physical size is proportional to scale factor ÷ PPI. The result compares B’s quantity with A’s. At the example diagonals of 24 and 27 inches, B’s modeled element is 1.125 times A’s physical size even though their logical workspaces match. These are mathematical examples, not measurements of an actual font or a tested monitor.
Use native resolution and a stated percentage
Enter the panel’s actual native pixel dimensions and its nominal diagonal. Then enter the percentage used for that display. Microsoft’s display-settings guidance distinguishes changing the size of apps/text through Scale from changing display resolution, and notes that lower-than-native resolutions can make text less sharp.
The calculation does not model application-specific DPI awareness, fractional-pixel rounding, font rasterization, browser zoom, accessibility text-size controls or every macOS “Looks like” mode. Those can change the appearance without following this simple percentage relation. Compare actual settings on each screen rather than applying the output as a command.
Equal workspace is a planning choice
A larger logical workspace can hold more interface area but does not guarantee readable text for a particular person or task. Matching physical UI size across screens can be useful for a desk plan; it does not establish an eye-health or ergonomic outcome. This page supplies no ideal viewing distance, medical advice or preferred scale.
Use the screen and desk dimension worksheet to check physical rectangles separately. For software text rendering, the existing external-monitor ClearType guide addresses a different Windows tuning task. Neither replaces the exact monitor, cable and computer display-mode specifications.
Method and sources
The PPI, logical-workspace and relative-size formulas are original geometry, with no hands-on display test. Source checked October 15, 2026: Microsoft, Change your screen resolution and layout in Windows . Your operating system and application may round or render differently from this model.