Most familiar units, abbreviations, and metric prefixes are recognized,
together with a generous leavening of exotica and a few constants
of nature including:

pi,π ratio of circumference to diameterc speed of light e charge on an electron g acceleration of gravity force same as g
mole Avogadro's number water pressure head per unit height of water au astronomical unit

The pound is a unit of mass. Compound names are run together,
e.g. lightyear. British units that differ from their US counterparts
are prefixed thus: brgallon. Currency is denoted belgiumfranc,
britainpound, etc.

The complete list of units can be found in /lib/units. A file
argument to units specifies a file to be used instead of /lib/units.
The –v flag causes units to print its entire database.

EXAMPLE

you have: 15 pounds force/in²
you want: atm

* 1.02069
/ .97973

FILES

/lib/units

SOURCE

/sys/src/cmd/units.y

BUGS

Since units does only multiplicative scale changes, it can convert
Kelvin to Rankine but not Centigrade to Fahrenheit.

Currency conversions are only as accurate as the last time someone
updated the database.