What does the 1.8MB consist of? Usually the first page view uses much more bandwidth, as any additional hits has much of the static content (css, js, images) cached. So visits*page size:
5270000*1.8 = 9486000MB (9.486TB) per month
/30 = 316.2 GB per day
The additional views per visitor will add some traffic, but at the same time repeated visitors with some static content already cached will likely use less, so without any additional info I would just use 316, or per day (or maybe 400-500 GB per dayto be on the plus side) as a rough estimate.
But it really depends on how much of the 1.8MB is static, cachable content, and how many repeated visitors you get. Also make sure it's actually loaded from your domain, if some of the content comes from 3rd party servers (for example ads), you can subtract it.