MODERN BOXES

Box Size & Dimensional Weight Calculator

Enter your product dimensions and get the recommended internal box size, an approximate flat blank size for material planning, and the dimensional weight carriers use to price your parcel. Free, no sign up.

Recommended internal box size
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Approximate flat blank size
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Dimensional weight (US, /139)
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Dimensional weight (/166)
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Common for many international services

How to read these numbers

Recommended internal box size

This is the inside measurement of the box, not the outside. Boxes are always specified by internal dimensions, because that is what has to fit your product. The clearance added depends on the fit you chose. Snug adds a small tolerance for light retail items, standard suits most products, and padded leaves room for tissue, foam, or a fitted insert.

Approximate flat blank size

Before a box is folded it is a flat sheet, called the blank. The blank size drives how much material each box uses, which is one of the things that drives cost. The number here is an estimate for planning. The exact blank depends on board thickness, tuck depth, and glue flap allowances, and is confirmed when the dieline is prepared.

Dimensional weight

Carriers charge on whichever is higher, the actual weight of your parcel or its dimensional weight. Dimensional weight is calculated from the size of the box, so an oversized box costs you money on every single order even when the product inside is light. This is the most common and most expensive packaging mistake we see. Sizing the box properly to the product usually pays for itself quickly.

An honest note on accuracy. This tool is for planning, not for production. It does not know your board grade, your carrier contract, or the exact dieline your box style needs. Use it to sanity check a size and to compare options. Before printing, send us the product dimensions and we will confirm the real internal size and build the dieline around it at no charge.

Get a free mockup and quote

Send your product dimensions and your logo. We will build the dieline, show you how the box will look, and send a quote. No cost and no commitment. Custom boxes from a low 100 unit minimum with 2 to 3 day production.

Request Your Free Quote

Common questions

How much clearance should a box have around the product?

A snug fit adds about 3mm each side, standard about 6mm, and padded about 15mm or more to leave room for tissue, foam, or an insert. Fragile products should use the padded setting.

Why does an oversized box cost more to ship?

Because carriers price on dimensional weight when it is higher than actual weight. A large light parcel is charged as if it were heavy, so wasted space costs you on every order.

Is the blank size exact?

No. It is an approximation for planning and material estimates. The final dieline depends on board thickness, style, tuck depth, and glue flaps.

What is the minimum order for custom boxes?

We produce custom printed boxes from a low 100 unit minimum, with 2 to 3 day production and free design support.

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