GNU Units | Hugonweb Annotated Link Bibliography

https://www.gnu.org/software/units/

A general purpose calculator for numbers with units.

Normal algebraic precedence applies, and you can use normal operators like +,-,*,/,^,sin,cos,exp,ln,log,round,floor,ceil.

Some extra guidance:

Symbol Explanation Example
* Low priority multiplication 3 N * m
<space> High priority multiplication -- Useful combined with / 3 N m
/ Low priority division -- Everything after is in the denominator 1/2 kg m = 0.5 / (kg m)
per Low priority division -- Everything after is in the denominator 1 per 2 kg m = 0.5 / (kg m)
| High priority division -- Only adjacent numbers are divided 1|2 kg m = 0.5 kg m
_ The result of the last computation