Galaxy S21 Ultra Ruler
Actual size, on screen

What fits on the Galaxy S21 Ultra screen – and what doesn't

• a US dollar bill (long side)155.96 mm / 6.14 infits in one go (1.5 mm to spare)
• a 4×6 photo (long side)152.4 mm / 6.00 infits in one go (5.1 mm to spare)
• a CD case (long side)142 mm / 5.59 infits in one go (15.5 mm to spare)
• a new pencil190 mm / 7.48 in32.5 mm too long – measure in 2 passes
• A4 paper (short side)210 mm / 8.27 in52.5 mm too long – measure in 2 passes
• Letter paper (short side)215.9 mm / 8.50 in58.4 mm too long – measure in 2 passes

The Galaxy S21 Ultra screen in numbers

• The screen is 157.5 mm (6.20 in) tall – 6.5 quarters laid end to end
• 1.84 times the long side of a credit card (85.6 mm)
• There are 203 physical pixels in every centimetre, 516 in every inch
• The finest 1 mm tick is 20.3 pixels apart

Compared with nearby models

Screen height compared with the Galaxy S21 Ultra (71.0 × 157.5 mm).

• Galaxy S212021 · 64.8 × 143.8 mm13.7 mm shorter
• Galaxy S222022 · 64.9 × 140.8 mm16.6 mm shorter
• Galaxy S22 Ultra2022 · 73.0 × 156.5 mm1.0 mm shorter

How this ruler stays true to size

The Galaxy S21 Ultra packs 516 pixels into every inch and draws 3.225 physical pixels per CSS pixel, so one millimetre is 6.30 CSS px. The ticks are rebuilt from that number and the live pixel ratio each time the page opens, which is why no calibration is needed on this model. The right side of the strip is metric (mm/cm) and the left side is inches in 1/16 steps; 1 inch = 25.4 mm.

If the ticks look off (display zoom or font-size settings change the ratio), hold a credit card against the screen – its long side is 85.6 mm – and use the card calibration. The calibration tool and the full device list are in Japanese, but the controls are simple: pick card or coin, drag to match. 日本語版はこちら.