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  • Writer's pictureJack Martin

Dimensional Weights vs Physical Weight

Shipping products to customers is a critical part of any e-commerce business. However, inaccurate shipping can lead to a negative customer experience and lost revenue. One of the key factors that can impact shipping accuracy is the way you set up package dimensions in your shipping software.


In this blog post, we'll explore the importance of properly setting up package dimensions in ShipStation, a popular shipping software platform, to ensure accurate shipping and happy customers. I like Shipstation but there are others like Shippo, ShippingEasy, EasyPost. Shopify's out of the box shipping features are limited by comparison to the above platforms. Love Shopify just not their shipping platform because it does not take this into account.


First and foremost, it's important to understand that carriers charge based on the weight and dimensions of a package. That means that if your package dimensions are incorrect, you could be overpaying for shipping. (I have seen this cost businesses a significant amount because they weren't paying attention to the details.) Additionally, carriers use a concept called dimensional weight, which is a pricing technique used for larger, lightweight packages.


Think about shipping a large painting in a frame. The painting and frame do not weigh much but the space it takes up in the van is quite large. The carrier's want to account for that lost space hence why they came up with dimensional weight.


If the dimensional weight of a package exceeds its physical weight, the carrier will charge you for the higher weight.


What is the equation for dimensional weight you may ask?


For Canada Post it is the following:



Length x Width x Height / 5000


So let's keep the painting example - we weigh the painting and frame in the box and it comes to 3 lbs or 1.36 kg. Canada Post is going to round up to the nearest half kilogram so in this case 1.5 kg. But wait, this is just the physical weight. The actual dimensions of the shipping box are 36 inches by 24 inches by 4 inches.


Since we are shipping this hypothetical painting with Canada Post let's convert this to centimetres (multiply by 2.54) and we get the follwoing:


60.96 x 91.44 x 10.16 = 56633.69 cm3

We then divide by 5000 to get the dimensional weight.


56633.69 / 5000 = 11.32 kg


So even though the painting physically only weighs 1.5 kg, Canada Post views it as weighing the equivalent of 11.3 kg or more than 10x. Again, remember that the package is rounded up to 11.5 kg.


This is a pretty exaggerated example but it highlights the difference between physical and dimensional weight. So how does this affect operating expenses?


If the painting were going from Toronto to Vancouver by Expedited Parcel taking into account just its physical weight or 1.5 kg it would cost $17.18. (Prices might be different if you have a plan with Canada Post and get volume discounts)


Now let's plug in our dimensional weight going the same distance and it would cost.....$38.41?



Yes, more than double. Hence the importance of understanding dimensional weight vs shipping weight.


You need to keep this in mind when you are shipping larger, bulkier items. Unless you are Wayfair, and even then sometimes Wayfair just lets the customer keep their item because the price, package size and return shipping negatively affect their margin, you need to ensure you know your dimensional weight for all your SKUs.


One of the benefits of ShipStation is that it offers the ability to automatically calculate rates based on package dimensions. This feature can save time and ensure accurate shipping costs for your customers. If you don't have accurate dimensions, you'll need to manually calculate shipping rates, which can be time-consuming and prone to errors. By automating this you save time every morning or early afternoon when you are getting your packages ready to ship out.


I can't stress enough how crucial it is to properly set up package dimensions in your shipping software. In ShipStation, this can be done by going to the "Settings" section and selecting "Packages" from the drop-down menu. From there, you can create package types and specify the dimensions for each package type.


I would also recommend getting some kind of digital scale that plugs into the computer at your pack station. This will give you accurate rates if the item weighs more than the package dimensions or vice versa. Dymo is an industry favourite.



In conclusion, accurate shipping is essential for any e-commerce business. Properly setting up package dimensions in ShipStation can help you avoid unexpected fees, save time, and ensure happy customers. By taking the time to accurately measure and input package dimensions, you can leverage ShipStation's features to optimize your shipping strategy and save money on shipping costs. Remember, carriers charge based on dimensional weight and physical weight, so it's important to measure both accurately to avoid any surprises in shipping costs.

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