B-flute
A medium-weight corrugated grade (~3 mm thick) that adds real crush resistance while still printing cleanly — common for shipping mailers.
B-flute sits between E-flute (thin, premium print) and C-flute (thick, true shipping carton). At ~3 mm thickness with ~47 flutes per linear foot, it offers about twice the stacking strength of E-flute while staying thin enough to die-cut sharp scores and tabs. That trade-off makes it the workhorse grade for branded shipping mailers — heavier than retail packaging, but still print-friendly enough to carry an identity.
If you're shipping items above ~3 lb, or if your boxes might get stacked in a warehouse before they reach the buyer, B-flute is usually a safer bet than E-flute. It costs marginally more per unit but takes the brunt of the shipping abuse so your goods don't.
Related terms
- DielineThe flat, two-dimensional template that defines exactly how a piece of packaging is cut, scored, and folded before it becomes a box.
- E-fluteA thin, fine corrugated material (~1.5 mm thick) used in mailer and retail boxes for a clean print surface with light cushioning.
- EmbossingA finishing technique that raises a portion of the printed surface using paired dies, creating a tactile relief without ink.
- FSC certificationA Forest Stewardship Council audit that traces paperboard back to forests managed for biodiversity, worker rights, and indigenous land use.