Units of Measure

Only abbreviate units of measure when there are numbers preceding them or in tables.


The tank was 3.5 m in diameter.

The mud pit was several meters away.

Don’t add “s” to abbreviations to make them plural, but do add the “s” if the word is spelled out.


The truck held 500 bbl of methanol. (not bbls)

The truck weighed 10 tons and had 23,489 miles on the odometer.

Don’t use symbols such as #, ‘ or ” to indicate units.

Use lbm for pounds of mass, lbf for pounds of force, ft for feet, and in. for inches.

And don’t ever use lbs. (See rule about plurals above.)

Use cm3 for cubic centimeters, not cc.

Use a slash ( / ) in place of the word “per.”

Example:  87 psi/ft

For English units, use a hyphen to indicate a product of two units.

For metric units, use a dot to indicate multiplication of two units.

(For a dot using Word software, insert symbol 00B7 from Unicode (hex) character set.)

Examples:  ft-lbf,  ohm·m

Units of Time English Metric
Second sec s
Minute min min
Hour hr h
Day D d
Year / Annum yr a

And don’t ever leave numbers stranded without their units of measure.

Whenever one of his students erred in such a way, my old geometry teacher, Mr. Perrone, used to demand in a thundering voice: “Apples, oranges, or bananas?”

He pronounced the latter “Bah-nah-nahs.”

It’s still ringing in my ears 30+ years later.


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