Custom Folding Carton Inserts

How to Measure for Folding Carton Inserts

Accuracy matters more with an insert than with almost any other packaging item, because a cut-out that is two millimetres too large lets the product move and one that is too small means it will not go in at all.

Measure the product with callipers if you have them. For a bottle, note the base diameter, the diameter at the point where the insert will grip it and the overall height. For a rectangular device, note length, width and depth, and any buttons or ports that should not be pressed. Then tell us the inside dimensions of the outer carton, or ask us to size the carton and insert together, which is the safer route.

Wherever possible, send us a sample product. We can then build the cut-outs to suit the real item rather than a drawing, which allows for small variations between batches of glass or moulded plastic.

Choosing the Card Grade

Light products such as lip balms or vials sit happily in a standard folding boxboard. Heavier items, including glass bottles and electronics, need a thicker board or a double-layer platform where the card folds back on itself for strength.

Where real weight or shock protection is needed, an E-flute corrugated insert gives more cushioning while still folding neatly. It is slightly bulkier, so we account for it when sizing the outer box. Kraft board is popular for brands that want a natural look inside the box, while white board shows printed messages most clearly.

Our advice is to choose the board based on the drop test you would want the box to pass, not on appearance alone. A beautiful insert that crumples in the post is a false economy.

Assembly on the Packing Bench

An insert that takes thirty seconds to fold will slow down every order you pack, so we design for speed as well as fit. Where we can, we use lock tabs that click into slots rather than relying on glue, and we keep the number of folds to the minimum the product needs, the same approach as our e-commerce packaging inserts.

For larger runs, ask us about pre-glued inserts. A small glue line applied during production means the insert pops open in one movement instead of being folded from flat, which adds very little to the cost and saves a lot of packing time.

It also helps to think about the order of packing. If the product goes into the insert first and then the pair drops into the carton, the insert needs a firm base and straight sides. If the insert goes in first, a thumb notch on each side makes it easier to seat the product and, later, for the customer to lift everything out together.

Printing and Finishing an Insert

Many inserts are left plain, and that is perfectly fine, especially when they sit underneath the product and are barely seen. If the insert is the first thing visible when the lid opens, though, print earns its place.

A single colour logo on the top surface is the simplest upgrade. Full colour print allows a pattern, a short message or step-by-step instructions next to each cavity. On premium packaging, a soft-touch or matt lamination makes the insert feel like part of the product rather than a piece of packing material.

We can also print the underside of a lift-out insert, where customers find it after removing the product. It is a good spot for a care guide, a social handle or a discount code for the next purchase.

Send the Inside of the Box and a Sample, Not Just the Product Size

An insert has to fit two things at once, the product and the carton, and the second is the one people forget. If you already have boxes, measure the inside length, width and depth of the box with the lid closed, or better, post us one; a few millimetres of difference between the outside and inside of a carton is enough to make an insert bind. Then send the product, or its measurements at the widest point with the cap on, and say which items share the insert and whether anything heavy or glass needs a double-layer platform. Say if the insert shows when the lid opens, since that decides the print.

With those details, a custom quote comes back by email within one working day, minimums kept low and quoted per job. The free design proof shows the flat dieline with every cut and fold; ordering inserts and new cartons together lets us show them assembled. Production takes 4 to 7 working days after approval and free tracked delivery reaches UK mainland addresses in 2 to 3 working days, the inserts arriving flat. Brands with small loose parts often add punched card inserts for accessories in the same job.