# What is the difference between “I earn \$500 each month” and “I earn \$500 per month”?

What is the difference between these two sentences?

I earn \$500 each month
I earn \$500 per month

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The latter describes your salary: if you sit at your desk and don't get fired, you'll get \$500. The former is more a description of the situation: somehow, by hook or by crook, I manage to scrape together \$500.

The use of "per" imply a causal connection between the passage of time and the arrival of your pay. "Each" encompasses the possibility there's no connection, and it's just happenstance.

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+1 for a good description of the distinction. But it seems to me just a slight difference of connotation, not a definite clear-cut implication — I’d feel that either per or each can be used for either of these situations, but per would be slightly more likely for the ‘by some consistent means’ case, and each slightly more likely for ‘by any means’. –  PLL Feb 1 '11 at 18:18
'I earn' implies that you work for the money. The use of per or each makes no difference to this. –  user3444 Feb 1 '11 at 21:27
`per` implies that you for work for a month. `each` implies that during the course of a month, you uncover enough renumerative work to reach that figure. So an office worker draws a \$500 per month salary; a salesman gets an average of \$500 each month in commission. –  Malvolio Feb 2 '11 at 1:13
I don't think most English-speaking people would take these words to have the distinction you're making. You certainly COULD use the words "each" and "per" this way if you explained yourself up front, but that's not how they are commonly understood. –  Jay Jan 24 '12 at 22:17

I'd say that "I earn \$500 per month" suggests that your monthly salary from a single source is \$500, whereas "I earn \$500 each month" could mean that you make \$500 from potentially multiple sources.

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The two are equivalent. Neither hold any implications as to how you come by the money; that is implied by 'earn'.

Per means 'for every' or 'for each', so it's almost exactly the same as just saying 'each'. Per is perhaps more common.

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I have to disagree. "Per" in the broader sense definitely carries the implication of causality. Consider "per your request". That can only mean "I did it because you asked me to". There's no some connotation in "each". –  Malvolio Feb 1 '11 at 19:47
@Malvolio: What Rhodri said. There are different definitions of per. –  user3444 Feb 1 '11 at 21:20
@Rhodri -- if you don't think there's causality in "50 miles per gallon", try removing the gasoline from your car, see how far you get. Candidly, I don't think it's honest argumentation to say, "Yes, you're correct in all the cases you cite, but the instant case is different, for reasons I feel no reason to explain." That's your position: every other case, `per` implies causality but in the case of time-ratio, nope, a wholly coincidentally relationship would suddenly suffice. –  Malvolio Feb 2 '11 at 1:10
@Malvolio: `per` is used in all sorts of ratios. Miles per gallon is a ratio of distance to unit of measure. Likewise, \$500 per month is a ratio of income to unit time. Neither imply causality. –  Scott Mitchell Feb 2 '11 at 4:33
RE "neither imply causality". Ditto. There may actually be causality in any ratio, but the use of "per" does not indicate it. I might just as well say, "My car is moving at 50 miles per hour." The hour did not cause my car to move. –  Jay Jan 24 '12 at 22:13

There is no difference. The following sentences are equivalent:

• I earn \$500 each month.
• I earn \$500 per month.
• I earn \$500 every month.
• I earn \$500 a month.
• My [monthly] salary is \$500.

From personal experience, I would say that per month is the least likely to be used in this context.

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"\$500 per month" connotes "I earn money at a rate of \$500 per month." So if you work for half a month, you will earn \$250. "I earn \$500 each month" implies that from the start of the month to the end of the month you acquire \$500.

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"Each month" is a fixed amount, "per month" can be an average.

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There are subtle differences in meaning.

“I earn \$500 each month” says that each month, considered separately, the sum of your receipts is \$500. This can mean that the sum equals \$500 exactly. But it can also mean \$500 at least. For example, you can write:

I earn \$500 each month. During peak months, I earn as much as \$800.

"I earn \$500 per month” express a rate, or linear relationship, between time and money. It means that over n months, the sum of your receipts is n × \$500. Again, this can mean that the monthly sum equals \$500 exactly. But it can also mean \$500 on average. For example, you can write:

I earn \$500 per month. This is considering the year as a whole. The summer months are slower, but I always make it up over the holidays.

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