USPS media mail and parcel post: how much to ship at once
If you’d like to ship some things via the the Postal Service (and have them see you waving from such great heights–no that’s not right…), how much should you mail at once? Basically, is it better to ship a lot of small boxes or a few big boxes?
I went through and figured it out for you based on their current rate chart. If you have media (books, CDs, notebooks, etc.), definitely do that, as media mail’s really cheap.
For media mail, the per pound price flattens out pretty quickly. You actually don’t get any break after 54lb (it’s all $0.38/lb at that point), but anything above 25lb is within 15% of that lowest per pound price.
On the other hand, parcel post–which takes equivalent amount of time as media mail but covers other types of contents–continues to decrease all the way through 70lb. To get within 15% of the per pound price of $0.73, you need to ship 55lb or more.
If what you’re planning to ship via parcel post is particularly dense and you only have a little bit to ship, priority mail flat rate boxes might actually turn out to be a good deal.
I believe in both cases, the cheapest option is to package things into the fewest number of boxes and evenly split the weight between the two.
Note, I believe this information is accurate as of April 2009, but make no guarantees after that.