Corrugated Boxes 101
Corrugated Boxes 101: Styles, Flutes and Board Strength
Everything you need to know about corrugated boxes. Not sure what to ask for? Start here. We'll handle the rest.
01
What is corrugated?
Corrugated board is two flat sheets of paper (liners) glued to a wavy middle layer called the flute. That wave is what gives a box its strength and cushioning. It's light, strong, and one of the most recycled packaging materials in the U.S.
02
Box styles we make
- RSC
RSC (Regular Slotted Container)
The standard shipping box. Flaps meet in the middle.
Best forEveryday shipping, storage, most products
- FOL
FOL (Full Overlap)
Outer flaps overlap fully across the box.
Best forHeavy or long items that need a stronger top and bottom
- HSC
HSC (Half Slotted Container)
An RSC with no top flaps, often paired with a lid.
Best forTrays, bulk produce, display bases
- D/C
Die-Cut
Cut to a custom shape with a steel die.
Best forMailers, trays, inserts, retail and specialty packaging
- 5PF
5-Panel Folder
One sheet that wraps around the product.
Best forLong, flat items like doors, trim, rods, frames
- PAD
Pads and Partitions
Flat sheets and dividers.
Best forLayering, separating, and protecting items inside a box
Don't see your style? We make it anyway. These are just the most common ones. If you need something different, just ask. We handle custom styles and one-off designs. Send us a sample, a drawing, or a photo, and we'll match it.
Book a Call03
Flute sizes
| Flute | Approx. thickness | Why you'd pick it |
|---|---|---|
| A | 1/4" | Maximum cushioning |
| B | 1/8" | Good crush resistance, clean die-cuts |
| C | 5/32" | The most common all-purpose shipping flute |
| E | 1/16" | Thin and smooth, great for printing and retail |
| BC (double wall) | about 1/4" | Heavy, bulky, or stacked loads |
A
- Approx. thickness
- 1/4"
- Why you'd pick it
- Maximum cushioning
B
- Approx. thickness
- 1/8"
- Why you'd pick it
- Good crush resistance, clean die-cuts
C
- Approx. thickness
- 5/32"
- Why you'd pick it
- The most common all-purpose shipping flute
E
- Approx. thickness
- 1/16"
- Why you'd pick it
- Thin and smooth, great for printing and retail
BC (double wall)
- Approx. thickness
- about 1/4"
- Why you'd pick it
- Heavy, bulky, or stacked loads
We work in single wall (SW) and double wall (DW) board, in any flute combination your product needs.
04
Board strength: ECT vs. Mullen
There are two ways to rate board strength. ECT (Edge Crush Test) measures how much weight a box can hold when stacked. It's the go-to rating for most shipping today. Mullen (Burst Test) measures how hard it is to puncture the side of a box. It matters for rough handling.
| Rating | Typical use |
|---|---|
| 32 ECT / 200# single wall | Standard shipping, up to about 65 lbs |
| 44 ECT / 275# single wall | Heavier products, up to about 95 lbs |
| 48 ECT+ double wall | Heavy, bulky, or high-stack loads |
32 ECT / 200# single wall
- Typical use
- Standard shipping, up to about 65 lbs
44 ECT / 275# single wall
- Typical use
- Heavier products, up to about 95 lbs
48 ECT+ double wall
- Typical use
- Heavy, bulky, or high-stack loads
Not sure which you need? Tell us what's going in the box and how it ships. We'll recommend the right board.
05
Printing and branding
We can print your logo, product info, handling symbols, or barcodes right on the box. Tell us your colors and artwork, and we'll quote it with your order.
06
How to measure a box
Box sizes are always listed as Length x Width x Depth, measured on the inside.
- 1
Length: the longer side of the opening.
- 2
Width: the shorter side of the opening.
- 3
Depth: the height from the bottom to the top of the opening.
Tip: measure your product, then add a little room for packing material.
Ready when you are.
Send us your L x W x D and what's going in the box. Not sure yet? Book a quick call and we'll figure it out together.