The short answer
A box style is a construction specification, not a catalog name. It tells the converter where to score the sheet, where to slot it, and where to fasten it. The four-digit number beside the style is a FEFCO code, and its first two digits name the design group.
Style sets the board a box consumes and the handling it survives, but it does not change the compression strength the board was rated for.
Corrugated box styles arrive as shorthand, so a quote says 0201, a drawing says FOL, and a purchase order says HSC. Each one is a construction specification telling the converter exactly where to crease the sheet, where to cut it, and where to apply glue.
On a specification sheet those styles look interchangeable, and they are not. Moving from a regular slotted container to a full overlap can add half again as much board to every box. That penalty depends on the box’s proportions rather than a fixed markup.
This reference covers the slotted family, how FEFCO numbering works, what full overlap costs in board, and why flap style cannot move a compression estimate.
What Slotted Actually Means
Every container in the slotted family begins as one flat sheet, creased so the panels fold and slotted where the flaps separate. Fold that blank into a tube, fasten the last panel to the first, and the box is finished.
That fastening point is the manufacturer’s joint, which most converters glue, though some stitch it with wire staples and others apply tape.
Containers leave the plant flat, and nothing gets assembled until someone squares the tube and closes the flaps. That is why slotted styles dominate: one sheet, one pass, no separate components.
Scores and slots also separate the families. Telescope styles need two blanks, while folder styles wrap a single blank around the product instead of forming a tube.
The Four Styles Ordered by Name
Four styles cover most of what ships, and the Fibre Box Association defines each one by the behavior of its flaps.
A regular slotted container carries flaps of equal length, with the two outer flaps running half the container width so they meet at the center. Its inner flaps do not meet unless length happens to equal width.
A half slotted container is the same box without the top flaps, which turns it into a tray or sleeve that usually ships alongside a separate cover.
An overlap slotted container carries outer flaps that overlap part way, while a full overlap reaches further because each outer flap covers the entire opening by itself.
| Style | Code | Outer flaps | Where it fits |
|---|---|---|---|
| Regular slotted (RSC) | 0201 | Half the width, meeting at center | General distribution |
| Half slotted (HSC) | 0200 | None at the top | Trays and parts bins |
| Overlap slotted (OSC) | 0202 | Partial overlap | Long boxes where flaps cannot meet |
| Full overlap (FOL) | 0203 | Full width, complete overlap | Heavy or abrasive loads |
Both blanks carry an identical panel run, so only flap length changes, and that changes sheet height by a full width.
How a FEFCO Number Is Built
Those numbers are not arbitrary. FEFCO and ESBO publish the code to replace long verbal descriptions with symbols that read the same in any language, and the International Corrugated Case Association adopted it worldwide.
Four digits, split in two: the first pair identifies the design group, while the second pair identifies one design inside it.
- 01 Commercial rolls and sheets
- 02 Slotted-type boxes
- 03 Telescope-type boxes
- 04 Folder-type boxes and trays
- 05 Slide-type boxes
- 06 Rigid-type boxes
- 07 Ready-glued cases
- 09 Interior fitments
Every drawing also carries an erection marking, where M indicates manual assembly while M/A indicates manual or automated assembly.
So 0427 decodes partially before anyone opens the book. Sitting in the folder and tray group means one blank, no tube, and no seam through the bottom.
The Center Special Styles
The slotted group does not stop at full overlap, because three center special designs exist for the case where inner flaps leave a gap.
A center special slotted container cuts inner and outer flaps to different lengths so both pairs meet at the center. A center special overlap keeps the inner flaps meeting while the outer flaps overlap partially. A center special full overlap keeps them meeting while the outer flaps cover the entire width.
Long containers are where these earn their cost. A 36 by 12 inch footprint gives inner flaps 6 inches of reach across a 36 inch span, so most of the bottom rests on a single layer. Cutting those inner flaps to 18 inches closes the gap.
None of it shows up on a standard price list, because every design needs its own slotting setup.
What Full Overlap Costs in Board
Full overlap consumes more board, and the amount is calculable rather than a number to request from a supplier.
Lay the blank flat. Across the sheet run four panels and a glue tab, totaling twice the length plus twice the width plus the tab. Up the sheet run a flap, the depth, then another flap.
A regular slotted container uses flaps half a width long, so its sheet stands D + W tall. A full overlap needs outer flaps a whole width long, so its sheet stands D + 2W tall, while the panel run stays put.
Divide one by the other and the extra board works out at W ÷ (D + W).
Running that calculation reveals a wide spread. A 12 by 12 by 12 inch container moves from 24 inches of sheet height to 36, which is 50 percent more board. A 12 by 9 by 18 inch container moves from 27 to 36, or 33 percent, and shallow containers pay the most because depth dilutes the penalty.
Part of that board never does any work, because the inner flaps stay at half a width and the sheet above them gets slotted away as trim.
Flaps and Stacking Strength
Box suppliers credit full overlap with extra stacking strength, yet the standard estimate for box compression contains no term for flaps.
That estimate takes three inputs: the edge crush value of the board, the board caliper, and the container perimeter. Change the style without touching board or perimeter, and the predicted figure sits exactly where it started.
The formula also assumes a square footprint and a regular slotted container. Applied to a two-piece telescope box, one Georgia Tech analysis reported 52 percent average error until the constants were refitted.
So what does the additional board buy? Two layers across the top and bottom instead of one, which resists puncture, shields the edges and corners, and survives abrasion against a trailer floor.
None of that is compression strength. A box that has to carry more weight in a stack needs a higher grade or a smaller perimeter, and the ECT grade chart is where that call gets made.
Test the finished pack if the number matters, because style effects can still appear in compression testing even where the estimate ignores them.
Glued, Stitched or Taped
The manufacturer’s joint looks like the weak point, and most people assume staples beat glue there.
A 2009 Cal Poly study tested that, comparing water-soluble glue at several coverages, three tape types, and staples set at different angles.
Peak force showed no significant difference across the three methods, and glue came out ahead on tensile strength alone.
Which leaves the choice to other factors. Adhesive runs fastest and leaves a clean interior surface, stitching holds where moisture would soften an adhesive, and tape suits short runs or repairs.
One caution on stitching. A stitched joint puts metal inside the box, which rules it out for food, electronics or anything a loose fastener could ruin, regardless of the strength data.
Telescope, Folder and Tray Styles
Past the slotted group, the numbering sorts by how the blank behaves rather than how the finished container looks.
Telescope styles in group 03 use two pieces, and a full telescope design has a cover reaching the whole depth of the body, which doubles the board on every wall.
Folders and trays in group 04 wrap around the product instead of forming a tube. A wrap-around blank is a regular slotted container turned on its side, so its top and bottom run unbroken with no flap seam. A five panel folder adds a fifth flap that layers the ends, which explains why long slender items ship inside them.
Group 06 holds the rigid designations, where a bliss box needs six or more joints sealed before it holds its shape.
Group 09 covers interior fitments, so partitions and pads carry codes too, which matters when a drawing calls out a number that is not a container.
Common Questions
What does RSC stand for?
Regular slotted container, or FEFCO 0201: four flaps of one length, with the two outer flaps meeting at the center of the container.
Is a full overlap box stronger than an RSC?
Stronger against puncture, abrasion and edge damage, because the top and bottom carry two layers of board. Compression strength tracks the board grade and the container perimeter instead, and the standard estimate has no flap term.
How much more board does a full overlap use?
Divide the container width by depth plus width. A 12 inch cube pays about 50 percent more sheet, while a deep narrow one pays closer to a third.
What is the difference between 0200 and 0201?
0201 carries flaps at both ends. 0200 is the same box without the top flaps, which turns it into a tray or sleeve that usually pairs with a separate cover.
Choosing a Style
Start with the load rather than the catalog, because weight sets the board grade while corrugated flute types set how that board handles crushing and printing.
Then let the failure mode pick the style. Flaps that cannot meet point toward an overlap or a center special, while edges that get dragged point toward full overlap. A part loaded from above and covered separately points toward a half slotted container.
Price the difference first, since a style adding half again as much sheet has to prevent more damage than it costs.
Verify the outside dimensions too, because as PackCalc notes, they cannot always be calculated by adding two calipers to every inside dimension.
What a style code does not tell you. It describes construction only, carrying no strength rating, no test result and no certification. Board grade, flute profile and the box maker’s certificate cover performance, while a compression or drop test covers the finished pack.
Key takeaways
- A box style is a construction specification, and its four-digit FEFCO number sorts by design group in the first two digits.
- The four common slotted styles differ only in what their outer flaps do: meet, stop short, overlap part way, or overlap fully.
- Full overlap adds board equal to W ÷ (D + W), so shallow wide containers pay considerably more than deep narrow ones.
- The standard compression estimate takes edge crush, caliper and perimeter, with no flap term in it.
- Glued, stitched and taped joints showed no significant difference in peak force in published testing.