twenty-two with names of their own — and what each one is made of
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
On the right of every row the same unit appears twice: above in base units, below through other named ones. Blank where the brochure itself leaves it blank.
Identical in dimension: radian and steradian, hertz and becquerel, gray and sievert. Reduce each one to base units and the difference vanishes.
The SI Brochure separates the hertz / becquerel pair outright: the hertz is only for periodic phenomena, the becquerel only for activity referred to a radionuclide.
The name of a unit carries what the dimension cannot: not how much, but of what.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 5 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
convert in your head · without a calculator
the ten largest by surface area — as squares at true scale, each inside the next
the A series · from A0 to A6
how many millimetres each size really is, and how much of the frame goes under the knife