Physical Scale Inspector

See real-world lengths from web pages at true 1:1 size on your screen.

Ever read "18-inch laptop" or "3 3/10 in depth" and have no idea if it actually fits? Physical Scale Inspector draws that measurement on your screen at true 1:1 size, so you can see it instead of guessing. How it works Select a measurement on any page — "18 in", "180 cm", "3 and 3/10 inches", "2(2/10) ft", anything. Right-click → Show real size. A real-size ruler appears. Drag it anywhere on the page to compare against product photos, spec tables, or your desk. Why install it Stop buying the wrong size. Sofa depth, monitor diagonal, a shelf gap, a phone case — see it at actual size before you order. Genuinely accurate. Calibrate once by matching an on-screen bar to the long edge of your bank or credit card (85.6 mm). No more guessing your monitor's DPI. No setup, no account. Works on any page, no sign-in, nothing collected. The popup also shows your detected screen resolution and pixel density so you can spot when numbers look off. Understands real-world notation. Fractions, mixed numbers, "inchs", 18-inchs, 18*cm, 18×inch, mm/cm/in/ft/m — it parses them. Comparison bars show your measurement next to familiar objects (a credit card, a sheet of A4, a ruler) for quick intuition. Good to know Calibrate at 100% browser zoom for best accuracy; you can recalibrate anytime from the popup, or fall back to entering your screen's diagonal in inches or cm. Desktop Chrome only — Chrome extensions don't run in Chrome on iPhone or Android. Built by Wenlong Sun — I'm looking for a job. linkedin.com/in/wenlongsun