What’s the Abbreviation for “Per Month”?

You may have tried to abbreviate the term “per month” but were unsure how to do it correctly.

This page looks at the different ways “per month” can be represented and whether there is a difference between the abbreviations.

What’s the Abbreviation for “Per Month”?

There are three standard abbreviations for the term “per month.” The first is “per mo.”, the second is “P/M.”, and the third is “PM.” However, when using the final abbreviation, “PM.”, it can sometimes be confused with the time from noon to midnight, “PM.” or “post meridian.”

abbreviation for per month

These examples show the three different ways you can abbreviate “per month.”

  • He pays $500 P/M for his rent.
  • He pays $500 PM for his rent.
  • He pays $500 per mo. for his rent.

For the style guides MLA, APA, AP, and Chicago there is no specific guidance on how to abbreviate “per month.” Therefore, if you are writing an essay or text in one of these styles, it is better to use the full term rather than the abbreviation.

PM. or P.M.

The abbreviation “PM”, which is also written as “P.M.” on occasions, is used to mean “per month.”

Some people prefer to use other abbreviations because of the potential confusion that can be caused by the time reference “PM”, which means “post meridian” or “past noon.” However, as long as the context is clear, it is unlikely there will be confusion on the part of the reader.

  • Last week, I saw a new apartment, which only cost $300 PM.
  • He gets paid less than $1000 P.M. at his new job.


The abbreviation “P/M.” represents the term “per month.” Using a “P” with a forward slash after it is commonly understood and accepted as meaning “per.” It is found in other terms such as “P/Wk.” which means “per week.”

  • He pays an extortionate amount P/M. for his car insurance.
  • I have been going to the doctor twice P/M. because I have terrible back pain.

Per mo. 

The abbreviations “per mo.” is used to mean “per month.” The word “mo.” always appears with a period because it is missing the rest of the letters from “month.”

  • She pays over $200 per mo. to heat her house because it is very spacious.
  • She was offered over $10,000 per mo. to come and work for the company.


The abbreviation “/mo.” is used to mean “per month.” The forward slash basically replaces the word “per”,  and it is commonly used for this purpose.

  • His salary is $2500 /mo., which is not enough to live on.
  • She pays $1000 /mo. for a personal trainer.


The term “per month” can be abbreviated in several ways. The most common are “PM.”, “P.M.”, “P/M”, “Per mo.”, and finally “/mo.”

If you are writing a piece of formal or academic writing, it is best not to abbreviate “per month” because there is no universally agreed abbreviation. Also, abbreviations, on the whole, are frowned upon in formal writing.