People usually ask this question with a mirror already in hand and a courier deadline approaching. The short version: the box you need is noticeably larger than the mirror, and the amount larger is set by how much cushioning sits between glass and cardboard.
The arithmetic
Carriers commonly advise at least 2 in of cushioning around a fragile item. Cushioning sits on both sides of each axis, so every plan dimension grows by about 4 in:
- A framed piece measuring 18 x 24 in needs an internal footprint around 22 x 28 in.
- A framed piece measuring 24 x 36 in needs an internal footprint around 28 x 40 in.
- A 1.5 in thick frame with hardware standing 0.5 in proud needs an internal depth around 6 in with full cushioning, or less with a suspension pack.
Those examples are the arithmetic of a published carrier guideline applied to a measured frame. They are not stock sizes. Your own numbers come from measuring your own piece.
One size or a family
| Situation | Better answer |
|---|---|
| A single product at one size | One carton cut to that internal size, with a fitted insert |
| Three or four sizes in a range | A telescoping base and lid, adjusted for height, plus one insert per size |
| Made to order pieces, every one different | A telescoping pair plus corner protectors and a flexible retention pad |
| Retail boxed mirrors sold in store | A printed inner carton and a plain outer shipper, two internal sizes |
The hardware catch
Almost every mirror box that fails on depth fails because someone measured the frame and not the back of the frame. A D ring, a sawtooth hanger, a wire, or a protruding cleat adds height at a single point, and that point presses through thin cushioning into the glass. Measure the back, or remove the hardware and ship it in a bag with the fixings.
Is the box or the insert doing the work
You can buy protection with a bigger box and more void fill, or with a smaller box and a smarter insert. The insert route is usually better: less material, a smaller parcel, lower dimensional weight, and better protection against the corner drop that actually breaks mirrors. A pair of corrugated end caps or a suspension pad that holds the piece off every wall lets the carton be slimmer than the 4 in rule suggests, as long as the piece never touches the outer board.
Ordering, and what is included
The minimum is 100 boxes. Pricing starts from about $0.48 per unit at bulk volumes, confirmed on your written quote, and the die, plates, design support, US shipping and a digital proof come with it. Because the die is included, a carton built to your frame costs no more to tool than a near standard carton, which is the reason not to settle for a box that is two inches too big on every axis. Turnaround is quoted per job in three lanes, rush (expedited production plus air freight), standard (air) and cost saver (sea), from about 7 business days, plus 2 to 5 for delivery.
Send the frame height, width, thickness with hardware and the weight to the quote form and we will size the carton and the insert together. For the full method, read how to size a mirror box, and see insert packaging for the protection options.
