custom size boxes for shipping

custom size boxes for shipping are boxes made to the dimensions of the product inside, rather than chosen from a stock range that is close enough but never quite right. When the length, width and depth match the packed product, with just enough room for protection, the parcel is lighter to handle, easier to stack and less likely to suffer damage from movement in transit. That fit also makes packing faster, because staff are not filling large empty spaces or forcing a lid closed over a product that is slightly too tall.

What are custom size boxes for shipping

A custom size box starts with measurement, not with a catalogue size. The product is measured as it will travel, including any wrap, insert or tissue that will be used. The internal size of the box is then set from those measurements, with a small allowance for easy packing and for the thickness of the board itself. This approach suits products that fall between stock sizes, products with an unusual shape, and orders where several items travel together in a set arrangement.

Stock boxes still have a place for simple, robust products, but they often create waste. A box that is too deep needs filler. A box that is too wide lets items slide. A box that is too shallow crushes a lid or a delicate corner. A custom size removes those compromises at the design stage, so the packing team can follow the same method for every order and the customer receives a parcel that looks intentional.

Internal size and external size

Internal size is the space available inside the finished box. External size is the size of the closed parcel, including board thickness, tape and any outer wrap. Postal and courier limits use the external size and the finished weight, so both figures matter. Always confirm which size a supplier is quoting, and ask for both internal and external measurements on the proof drawing, especially for tight fits where a few millimetres decide whether a lid closes cleanly.

How to measure a product for shipping

Measure the longest side, then the widest side, then the height, with the product in its retail pack or wrap if it will travel that way. For an irregular shape, measure the longest, widest and tallest points, because a protruding handle, lid or corner will decide the fit. For a set, arrange the items as they will be packed and measure the whole group, including dividers. Take the measurement twice, and note the weight of the finished parcel, because size and weight together guide board choice and postal format. The Royal Mail size and weight guide shows how finished size and weight relate to letter, large letter, small parcel and medium parcel formats.

Why a close fit protects better

Movement is the main cause of damage in a parcel that is otherwise well made. A product that can slide will gain speed before it hits a box wall, and repeated small impacts can loosen a lid, dent a corner or break a fragile part. A close fit, with a fitted insert or a small amount of paper fill, keeps the product centred. That is particularly important for glass, ceramics, bottles and electronics, where a single impact can cause a return even if the outer box looks undamaged.

Allowance for protection and inserts

A close fit does not mean a tight squeeze. Leave room for the protection the product actually needs. A foam pad, a card divider or a layer of tissue each take space, and that space must be included in the internal size. If the insert is added after the box size is fixed, it may force the product against the wall or prevent the lid from closing. Plan the insert and the box together, and test pack with the real product before approving a full run.

Choosing a board and structure for shipping

Corrugated board is the usual choice for shipping because it combines strength with light weight. Finer flutes give a smooth surface for print and a neat fold for mailers, while stronger flutes give more cushioning for heavier or stacked parcels. Single wall board suits most online orders, while double wall board suits heavier goods, bulk orders and parcels that will be stacked under other parcels in a warehouse or vehicle.

Structure matters as much as board. A regular carton with taped flaps is fast to pack and strong for multi item orders. A mailer with a folding lid gives a cleaner opening and is better for single products and subscription parcels. A box with a crash lock base assembles quickly and holds its shape under weight, which helps a busy packing team. Choose the structure that matches how the box will be packed, sealed and opened, not just how it looks flat.

Print and branding on a sized box

Print on a custom size box can be as simple as a logo on the outside or as complete as full colour artwork inside and out. A sized box gives print a better canvas, because artwork can be placed with the finished proportions in mind, rather than stretched across a stock box that is too large. Keep key artwork clear of tape, labels and folds, and check the proof in folded form so that a design that looks balanced flat still looks balanced when assembled.

Labels, tape and handling marks

Leave a flat, unprinted or lightly printed area for the shipping label, so barcodes scan cleanly. If tape will be used, avoid placing fine detail where tape will cover it. Handling marks, such as a fragile note or an arrow showing the correct orientation, are useful when they are clear and honest, but they should not replace proper internal protection. A box that needs a warning to survive is usually a box that needs a stronger board or a better insert.

Ordering custom size boxes for shipping

A good quote request includes the internal size needed, the product type and weight, the quantity, the board preference, the print requirement and any insert. If you are unsure about board grade, describe how the parcel will travel, whether it will be stacked, and whether it contains fragile items. That context helps a supplier recommend a board that protects without adding unnecessary weight or bulk.

Standard lead times after final artwork approval are 10 to 14 working days, corrugated 12 to 15 working days, and rigid or specialist 13 to 16 working days. These are production lead times, not a guaranteed delivery date. For a first order, allow time for a proof and a test pack, and order reprints before stock runs low, especially ahead of busy trading periods.

You can request a tailored quote with your measurements, browse the full shop range for related styles, and read delivery information for planning. Related sized options include custom size shipping boxes and custom size mailer boxes, and the Personalized Mailer Boxes home page gives an overview of the full range.

Testing a new size before a full order

Test packing is the cheapest quality check available. Pack the real product, seal the box as it will be sealed for customers, weigh it, measure the finished parcel and drop it gently from bench height onto a firm surface. Check for movement, for pressure on corners or lids, and for any difficulty opening the box. If a problem appears in a test pack, it will appear many times across a full order, so fix the size, board or insert before production.

When a stock size is still the better choice

A stock size can be sensible for a short run, a simple robust product or a trial where the exact size is not yet known. If a stock box already gives a close fit with minimal filler and the finished parcel sits comfortably within its postal format, there is no need to change it. Custom sizing earns its place when the product, the set, the protection or the presentation makes a stock box a compromise rather than a solution.

Frequently asked questions about custom size boxes for shipping

What measurements do I need for custom size boxes for shipping?

Send the length, width and depth of the product as packed, including wrap or retail packaging, plus the finished parcel weight if known. For sets, send the arrangement and the size of the whole group, including dividers.

Should I order by internal or external size?

Order by internal size for fit, but check external size and weight for posting. Ask for both figures on the proof, because board thickness, tape and wrap all add to the finished parcel size.

How much allowance should I leave for protection?

Leave enough room for the insert or filler you will actually use, without leaving so much room that the product can slide. Test pack with the real insert to confirm the allowance before approving production.

How long does production take after artwork approval?

Standard production is 10 to 14 working days after final artwork approval, corrugated is 12 to 15 working days, and rigid or specialist is 13 to 16 working days. These are production lead times, not a guaranteed delivery date.

Will a custom size box reduce postage volume?

It often can, because a closer fit removes empty space and filler. The finished parcel must still be checked against the chosen postal or courier format, because size and weight together decide the format.