Test Your Screens

Grab your phone. Measure its screen width and height, then divide the longer by the shorter to get the aspect ratio. Most modern phones land near 19.5:9 or 20:9 — tall rectangles built for one-handed scrolling. An iPad Pro is 4:3, much closer to a square.

Now check your TV. Divide its width by its height and you get roughly 1.78 — that is 16:9. A theater screen runs closer to 2.4. Finally, take a sheet of A4 and divide its height by its width: about 1.414, the square root of 2. Every measurement you just took is an aspect ratio hiding in plain sight.