Zones & Reach

Before a single claim, a test. Eight dots. Tap them all as fast as you can — then look at what the screen reveals about your own hand.

Here is the whole principle: a control’s home is decided by how the hand reaches it, not by where the content happens to sit. On a phone held one-handed, the thumb sweeps a fixed arc — roughly the bottom two-thirds on the holding side. Inside that arc, taps are free. Outside it, every tap costs a stretch, a grip-shift, or a second hand.

The busiest verbs of your app — send, next, like, pay, back — are pressed hundreds of times a session. Put them where the thumb rests and the app feels effortless. Put them in the far corner and it feels, in a way users can never quite name, tiring.

Reach is not one map — it changes with the device, the hand, and the grip. Pick a phone, a hand, and a spot for the main button, and watch the real numbers move: how far the thumb travels, how far it travels in a year, the fatigue, the predicted misses.

A target floating in open screen can be missed on every side. A target flush to the edge can be missed on only three — the boundary stops your finger for free. Feel the difference as a game: fifteen seconds, hit as many as you can. Play both modes, then read your own accuracy.

One button matters: Accept & Pay. But a cookie bar, a chat bubble and a newsletter all want the same bottom corner, and they arrive late — right as your thumb commits. A ten-second timer runs. Try to pay. Then try the zoned version, where every overlay has an assigned seat.

Everything you have felt, in one screen. The layout is tidy — nothing messy — but the main action sits where the thumb cannot easily go. Drag it into the thumb zone (everything snaps to a clean grid, so the only thing you ever change is the reach, never the neatness), then grade it: the reach zones appear over your layout and score it.

Reach is a strong default, not a law. The skill is knowing where it flips — and why.

Nothing here is redesigned — no new colours, no new content. One control moves from the top corner to the thumb zone, and the nav follows. Flip between them and watch the reach map turn from red to green, and the numbers with it.

Recreated in motion, no screenshots — watch where each one puts the thing you tap most.

Feeling the tax is half of it. Here is the loop a designer runs to place controls on purpose — five steps, in order, on every screen.

Five face-offs. The same screen, two placements — one taxes the thumb, one sits where it rests. Pick the kinder one, then see why.

Six words for placing controls by the hand. Tap a card to flip it.

Ten questions in seven formats — multiple choice, multi-correct, fill-in, match, order, read-think-connect and write-your-own — each with layered hints: a nudge, the reasoning, then a deeper connection. Served from the question bank, never hardcoded.

Don’t take my word for it — take your own. Think of the five apps you open most. For each, picture the button you tap again and again: is it down by your thumb, or up in the far corner? These five start in the thumb zone — tap any whose main action really lives up top on your phone.