With Canadian post though, a common misconception is that only weight matters, when in fact two packages that are the same weight but different sizes may require different postage. This is different to Australia for example, where companies such as Packqueen provide a range of Australia Post Boxes that are easy to assemble and post to your destination of choice. Unlike with USPS, where they have flat rate 'whatever you can fit inside' mailers, with Canada Post it's difficult to know exactly how much your package is going to be, as your postage is calculated based on weight, volume, and destination, even within Canada. Oftentimes when you go to send a parcel through Canada Post, you bring your package to the post office so they can weigh it and charge you postage according to where you're going to send it.
