Units and measures
Unit charts are used in a hurry — halfway through a recipe, in front of a hardware shelf, reading a specification written on the other side of an ocean. So these are arranged for the glance rather than for study.
The SI sheet carries all twenty multipliers from quetta down to quecto, including the four added in 2022 that most printed tables still lack. The paper sheet draws the A series from A0 to A6 at true relative size, so the halving rule is something you see rather than something you are told. And the imperial sheet gives the arithmetic that gets close enough without a calculator, which is the only kind of conversion anyone does standing up.
The conversion sheet earns its place in a kitchen. The other two belong above a desk, or beside the printer that will be arguing about paper sizes anyway.
IMPERIAL UNITS
convert in your head · without a calculator
CURRENCY MINOR UNITS
178 codes in the standard: 139 currencies divide by 100, 17 do not divide at all, 7 divide by 1,000 — and 25 codes are not money you can spend
APERTURE, SHUTTER, ISO
one stop is twice the light: three scales with the same step on each
NEEDLES AND YARN
knitting needle sizes in three systems — metric, old UK, US — and the 0–7 yarn weights per the Craft Yarn Council
THE LARGEST COUNTRIES
the ten largest by surface area — as squares at true scale, each inside the next
LEAP SECONDS
27 seconds added to UTC since 1972, none since 2016 — the longest run there has ever been
PAPER SIZES
the A series · from A0 to A6
PHOTO PRINT SIZES
how many millimetres each size really is, and how much of the frame goes under the knife
CAMERA SENSORS
seven sizes at one scale, with the crop factor computed from the diagonal
SI BASE UNITS
seven constants given an exact number — and the seven units that follow from them
SI UNITS WITHOUT NAMES
the endless rest: assembled from the base and the named units, and never with a factor
SI DERIVED UNITS
twenty-two with names of their own — and what each one is made of