Short answer: size the RSC to your packed load plus cushion, then check the proportions. Unlike most box styles, an RSC has a shape rule baked into it, because all four flaps are cut at half the box width so that the outer pair meets in the middle. If the proportions are wrong the box still gets made, it just behaves badly.
Diagnose it by symptom
| What you are seeing | What it means | What to change |
|---|---|---|
| The flaps overlap in the middle | The box is narrower than the flap length implies, usually a spec error | Check the width the flaps were cut to against the box width |
| A visible gap between the outer flaps | Same error in the other direction, and the tape is doing structural work | Re-cut to true half width, or move to a full overlap style |
| Long floppy flaps that buckle | Width is much greater than depth, a shallow wide box | Consider a full overlap or a telescoping lid and base instead |
| The box bursts at the manufacturer's joint | Tall and narrow, so the load concentrates on a small closure | Rearrange the contents to a squarer footprint, or step up the board |
| Product moves inside | Oversized for the load | Re-measure the packed block and cut the clearance back to the cushion thickness |
Landing on the number
- Measure the packed load at its widest in each axis.
- Add the cushion or insert thickness on each face.
- Write the two opening dimensions longer first: that is length then width. The remaining figure is depth.
- Compare width against depth. If they are wildly different, see whether rearranging the contents fixes it before you change the box style.
- Mark the figure internal and ask the quote to confirm it is internal.
Why the squarer box is cheaper
The flat blank runs roughly twice the length plus twice the width along the scores, plus a joint tab. A long, thin box has a much larger perimeter than a squarer box of the same volume, so it uses more board per unit shipped. If you have any freedom over how the contents are arranged inside, arranging them squarer is a direct material saving on every box you ever order, not a one-off.
When to stop using an RSC
It is the default style, not the right style for everything. Very shallow and wide loads do better in a full overlap or a two-piece telescoping box. Heavy stacked goods do better with full overlap flaps, which double the board across the whole top and bottom. Anything a customer opens and sees deserves a mailer style with a printed interior rather than a taped transit box.
What to send and what it costs
Send the internal dimension, the packed weight of one box and the stack height on a pallet. That is enough for a board grade and a written price. Minimum order is 100 boxes, from about $0.48 per unit at bulk volumes, confirmed on your written quote, with the die, plates, design support, US shipping and a digital proof before printing included. We make in West Chicago in the US and Guangzhou in China, and turnaround is quoted per product 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.
The construction detail behind all of this is on how to size a regular slotted box, and you can order at corrugated boxes.
Send your load measurement through the quote form and we will confirm the proportions, the grade and the price in writing.
