abbreviations: plurals

Follow the guidelines below to form the plural of different types of abbreviations.

Plurals formed with s alone

Add an s, but not an apostrophe, to form the plural of most abbreviations:

• ADMs
• BMWs
• CAs
• CRs
• FTEs
• GICs
• MPs
• PCBs
• 747s

Add an s without an apostrophe to form the plural of abbreviations with only one period. The s is added before the period:

• Gens.
• pts.

Plurals formed with apostrophe s

In cases where the resulting form would be ambiguous, add an apostrophe before the s:

• Q’s and A’s
• SIN’s

Add an apostrophe and s to form the plural of abbreviations containing more than one period:

• c.o.d.’s
• G.M.’s

Use an apostrophe and s to form the plural of numerical names of aircraft ending in a single letter:

• 727-100C’s
• 747B’s
• Cessna 402B’s

Irregular plurals

The plurals of Mr. and Mrs. are irregular:

• Mr., Messrs.
• Mrs., Mmes.

The plural forms of the abbreviations for certain bibliographic references are different:

Note that SI/metric symbols maintain the same form for both singular and plural and are written without periods, except at the end of a sentence:

• 1 cm
• 5 cm
• 75 kg
• The boxer weighed only 75 kg.