All tools / Paperboard reference

Paperboard reference.

SBS, clay-coated chipboard, kraft-back, and plain chipboard in one place: what the calipers mean, what each grade is for, and a quick stack calculator for pads, partitions, and rigid box builds. One point equals 0.001 inch.

Caliper converter.

Enter a caliper in points to convert to inches and millimeters. One point equals 0.001 inch.

Caliper (points)

Caliper0.018 in (0.457 mm)

Tolerance: board caliper is typically held to about plus or minus 5 percent, and laminated or printed sheets gain a little thickness. For tight-fitting trays and rigid box wraps, spec the caliper on the purchase order and confirm against the mill certificate.

Working notes.

Grain directionScores fold cleanest with the grain; plan carton grain parallel to the main score lines

Score allowanceHeavier calipers need wider creasing rules; 24 pt and up often needs a double score

Print surfaceC1S coats one side, C2S coats both; chipboard backs print poorly without a liner

SBS calipers and typical uses.

Solid bleached sulfate, the premium white board for retail packaging.

Points	Inches	mm	Best use in design
10	0.010	0.25	Inserts, lids, lightweight sleeves
12	0.012	0.30	Pharma cartons, small folding cartons
14	0.014	0.36	Standard folding cartons, sleeves
16	0.016	0.41	Cosmetics cartons, heavier sleeves
18	0.018	0.46	Blister cards, club-pack cartons
20	0.020	0.51	Heavy cartons, header cards
24	0.024	0.61	Rigid-feel cartons, heavy blister, hang tags
28	0.028	0.71	Extra-heavy cards, tiers, small displays

Board families compared.

Grade	Surface	Typical range	Pick it for
SBS (C1S / C2S)	Bright white, premium print	10–28 pt	Retail cartons, blister cards, luxury packaging
CCNB chipboard	Clay-coated face, gray back	16–30 pt	Economical cartons, cereal-box construction
CUK / CNK kraft back	Coated face, kraft back	14–24 pt	Beverage carriers, strength with moisture exposure
Uncoated chipboard	Gray both sides, no coating	20–60 pt	Pads, backers, partitions, rigid box cores

Chipboard for structure.

Points	Inches	Best use in design
22	0.022	Pads, layer sheets, mailer stiffeners
30	0.030	Backers, partitions, tier sheets
40	0.040	Rigid box walls, easel backs, riser cores
50	0.050	Heavy rigid boxes, structural display parts
60	0.060	Premium rigid setup boxes, book-style bases

Grades and calipers here reflect common converting practice; every mill runs its own deck. When a build mixes boards, spec each part's grade and caliper separately, since a 40 pt chipboard core wrapped in 12 pt SBS behaves nothing like a single 52 pt sheet.

Disclaimer: These tools were built at my desk to keep the answers I need in one place. I’m sharing them in the hope that they make your design process a little easier too. The math is checked against published standards and real-world experience, but specs change and materials vary. If you spot anything that seems off, please email me at donna@donnakadell.design and I’ll take a look.

Enjoy.