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How to Find the Right Size Box

Your e-commerce store is almost all ready to go. You have orders coming in and a product waiting to be shipped. You just have one final step before you can fulfil your orders – finding the right size box to pack your product in.


At first glance, this seems like a straightforward task. Find a box with the correct dimensions, and you’re done, right? But there are a few common questions and mistakes that can cause problems for new e-commerce businesses.


In this short guide, we’ll walk you through the most important questions and help you find the perfect size box for your needs.


What are you shipping? Is your product breakable?


Start with the basics. What product are you shipping, and how big is it? Measure the item’s dimensions in this order: length, width, height. Is it a standard size and shape, or is it a speciality item that may not fit into a standard box? Can you turn your item to make it fit in a smaller box?


Follow this golden rule: look for a box that is just large enough to fit your product – and maybe void fill – but not much larger. If you buy a box that is too big, you end up paying more for packaging materials and shipping (and your operation becomes less eco-friendly).


Is your product self-supporting within the box, or does it need void fill or protective packaging to hold it in place?  If you are shipping a product that isn’t fragile – like a book or a T-shirt – then you don’t have to worry about leaving space in the box for void fill. You can simply choose a box that fits your product snugly, no need for any protective padding.


But if your product is breakable, you need to take extra care to prevent damage. You must leave a little bit of extra space around the product for void fill – kraft paper, tissue paper or bubble wrap – to keep the item from moving around inside the box. But while it’s tempting to err on the side of safety with protective packaging, don’t go overboard. Use just enough void fill or padding for your needs


The right size box for a non-breakable product

The right size box for a breakable product


How are a box’s dimensions measured?


A box’s dimensions always measure its internal measurements, not external, in order of length, width and height. For example, a single wall cardboard box with dimensions 381 x 248 x 127 mm is a box with an interior length of 381 mm, an interior width of 248 mm and an interior height of 127 mm.


External dimensions, however, are important when sending parcels through the Royal Mail. Small, medium and large boxes must stay within these exterior measurements and weight limits.


Royal Mail Size Weight Length Width Height
Large Letter 0.75kg 353mm 250mm 25mm
Small Parcel 2kg 450mm 350mm 160mm
Medium Parcel 20kg 610mm 460mm 460mm




To calculate the exterior measurements of DS Smith boxes for Royal Mail shipments, simply add the box thickness (x 2) to the length, width and height dimensions. Single wall cardboard boxes have a thickness of 3 mm, so you would add 6 mm to each dimension. Double wall cardboard boxes have a thickness of 5 mm, so you would add 10 mm to each dimension.


Are you shipping multiple products at once?


Since e-commerce businesses often sell diverse products and customers buy them in a variety of combinations, shipping orders can feel like constructing a 3-D puzzle. Get creative when you try to fit multiple items into one box, turning and nestling them in various ways to find the best arrangement. You may have to buy several different sizes of boxes to fulfil orders. Or you may find an adaptable option, like Made2Fit cardboard boxes, is better for your changing needs.



Pay attention to customer shopping behaviours over time. Do people often buy certain items together? Do you offer incentives or discounts for customers to buy a specific quantity of products? Use this information to predict what size boxes will be most popular.


With all of the different types of packaging on the market, you want to make an informed choice for your business. Give the DS Smith ePack cardboard box finder a try, to find the right size cardboard box for your products:


Cardboard Box Finder


2020-09-09T13:27:03+01:00January 8th, 2019|Categories: Packaging Basics|

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