Lenovo Thinkpad X61 Tablet

Pixel pitch (computed from PPI; a rectangular estimate, not a measured panel pitch)

175.6 um

Physical size (computed from the rectangle, not the usable area)

9.68 by 7.26 in (24.6 by 18.4 cm)

Aspect ratio (computed)

4:3

Megapixels (computed)

1.47

Looks sharp from (assuming 20/20 vision, one pixel per arcminute)

23.8 in and further

Pixels per degree at an assumed 20 in viewing distance

50.5

Density as a percentage of Windows' 96 PPI reference (a ratio, not a scaling recommendation)

151%

macOS 2x workspace (hypothetical: half the native resolution in points)

700 by 525 points

Every row above is computed here from the stated resolution and the stated diagonal. With w and h in pixels and the diagonal in inches: PPI = sqrt(w^2 + h^2) / diagonal, which here is sqrt(1400^2 + 1050^2) / 12.1; pixel pitch = 25.4 mm / PPI; physical size = pixels / PPI, which is the full panel rectangle and not the usable area, so a screen with rounded corners or a notch has less usable area than the size shown; sharpness distance = 1 / (PPI x tan(1/60 degree)), the distance at which one pixel spans one arcminute for 20/20 vision; pixels per degree = 2 x distance x tan(0.5 degree) x PPI at the assumed viewing distance. Values are rounded to two decimals, and to one decimal for the pitch, the sizes in centimeters, the distances, and the pixels per degree.