I have a contract for a new job here and its monthly rate doesn't add up to the rate I expect.

I was offered $1000* per week in the interview process. The contract rate uses a monthly basis however, so by my calculations I should receive:

• Using weeks as the smallest timeframe > (1000 * 52) / 12 = $4333 per month or:

• Using days as the smallest timeframe > ((1000 / 7) * 365) / 12 = $4345 per month

As the rate was offered in weeks, I expected $4333.

They offered $4000 per month.

At the time they didn't explain their calculations so I assumed it was an exchange rate issue (that I wont muddy the water with, but please trust me that it's unrelated to the matter at hand), however following discussions indicate we were indeed using the correct exchange rate, however they were calculating the monthly rate using the value of '4' for the number of weeks in a month. i.e. simply:

• 1000 * 4 = $4000

Question: Is this a standard accounting rule of thumb, or otherwise expected and ok?

Currently they're telling me I'm using the incorrect exchange rate, and the whole 4 weeks in a month seems very natural to them. I believe I can clear this up in the next email iteration, but I don't want to stuff up rate negotiations and I have to try on for size that maybe I'm the one at issue.

Am I?

It is a US based company working out of Asia.

^{* not the real amount, but set at 1000 to make the ratios clearer}