yanameter is the ironical SI redefinition you didn't ask for.
One yana (ya) is defined as exactly 179.5 cm — the height of a real human being, who is very real and very tall.
The converter rebases any length into yana. The stack tab lets you place two coordinates and watch how many full yanas fit between them, with a 179.5-cm-tall image rendered to scale between the markers.
Made in Luxembourg. Published at yanameter.serlo.lu. No tracking, no cookies, no telemetry. State stays on your device.