Paperboard Grades Explained: SBS vs FBB vs CUK vs CRB

Paperboard grades describe what a board is made of and how it’s finished. The four main grades for folding cartons are SBS (solid bleached sulfate), FBB (folding boxboard), CUK (coated unbleached kraft) and CRB (coated recycled board). SBS is the bright white premium choice, FBB is a lighter, stiff alternative, CUK is the strongest, and CRB is the most economical, recycled option.

If you’ve ever asked a packaging supplier for a quote and been asked “which board grade?”, this guide is for you.

Paperboard grades at a glance

Grade	Also called	Fiber	Color (front/back)	Strength	Print quality	Relative cost
SBS	Solid bleached board, C1S or C2S board	Virgin bleached chemical pulp	White/white	Good	Excellent	High
FBB	GC1, GC2, folding boxboard	Virgin, layered chemical and mechanical pulp	White / cream or white	Good stiffness for its weight	Very good	Medium to high
CUK	SUS, coated natural kraft	Virgin unbleached kraft pulp	White coated / brown	Very high	Good	Medium
CRB	CCNB, WLC, recycled board	Recycled fiber	White coated / grey	Moderate	Good	Low

SBS: solid bleached sulfate

SBS is made entirely from bleached virgin wood pulp, so it’s white all the way through. It’s usually clay-coated on one side (C1S) for printing, or on both sides (C2S) when the inside of the box is printed too.

What it’s good at:

• The cleanest, brightest print surface, so colors look accurate and photos look sharp
• A smooth surface that works well with foil, spot UV, embossing and soft-touch lamination
• A clean, white inside, with no grey or brown showing at cut edges

Where you’ll see it: cosmetics and skincare, fragrance, pharmaceuticals, premium food and confectionery, and retail packaging where the box has to look perfect. It’s also a common choice for food that touches the board directly, because it’s made from virgin fiber.

FBB: folding boxboard

FBB is built in layers. The outer layers are bleached chemical pulp, and the middle layer is mechanical pulp, which is bulkier. That structure makes FBB stiffer than SBS at the same weight, so you can often use a lighter board and still get a rigid box.

The back is often a cream or light shade rather than bright white, which matters only if the inside of the box is visible. FBB is very common in Europe, where you’ll see it graded as GC1 (white back) and GC2 (cream back).

Good for: food and confectionery cartons, cosmetics, pharmaceuticals and retail products where you want good print and stiffness at a sensible cost.

CUK: coated unbleached kraft

CUK is made from unbleached virgin kraft fiber, the same long, strong fibers used for brown paper bags, with a white clay coating on the printed side. The back stays brown.

Its big advantage is strength. Long kraft fibers resist tearing and hold up well in cold and damp conditions, which is why CUK is used for beverage carriers (like the cardboard around a six-pack), frozen food cartons and heavier products.

Good for: drinks multipacks, frozen and chilled food, hardware and anything that needs a tough carton.

CRB: coated recycled board

CRB is made from recycled fiber, usually with a white coated top layer for printing and a grey or brown back. In the US it’s often called clay-coated news back (CCNB), and in Europe the equivalent is white lined chipboard (WLC, graded GD or GT).

It’s the most economical grade and has strong sustainability credentials because it’s made from recovered paper. The trade-off is slightly lower brightness, a grey inside and less strength than virgin boards.

Good for: cereal and dry food boxes (usually with an inner bag), toys, games, household goods and shoe boxes. For food that touches the board directly, recycled board usually needs a liner or barrier, so check with your supplier.

What about plain kraft board?

Uncoated kraft board has no white coating at all, so the natural brown shows on both sides. It’s popular with eco-friendly brands that want an earthy look. Print sits on the brown surface, so colors appear darker and more muted. White ink or a white underlayer can help logos pop. If you’re comparing kraft with corrugated, our guide to what cardboard is made of explains the difference.

Board thickness: points, GSM and microns

Paperboard thickness is measured in points (pt) in the US. One point is 0.001 inch. In Europe and Asia, suppliers usually describe board by weight in grams per square meter (GSM) or by thickness in microns.

Thickness (pt)	Thickness (mm)	Typical use
14 pt	0.36 mm	Small, light products, sleeves, tags
16 pt	0.41 mm	Cosmetic and retail cartons
18 pt	0.46 mm	Standard retail boxes
20 pt	0.51 mm	Heavier products, larger cartons
24 pt	0.61 mm	Premium or heavy items, display boxes

GSM and points don’t convert exactly, because two boards with the same weight can have different thickness (FBB is bulkier than SBS, for example). As a rough guide, 18 pt SBS is roughly 300 GSM. When in doubt, ask for a physical sample.

Rigid boxes are a different category. They’re made from thick chipboard (greyboard), usually 1 to 3 mm, wrapped in printed paper. You can see this on our custom rigid boxes.

How to choose the right paperboard grade

Ask yourself these questions:

1. Does the box need to look premium? Choose SBS or FBB.
2. Will the inside of the box be seen or printed? SBS (C2S) gives a white inside.
3. Is the product heavy, cold or wet? CUK is the strongest choice.
4. Is cost the main driver, or a recycled story? CRB is the most economical.
5. Do you want a natural, earthy look? Go with uncoated kraft.
6. Will it touch food directly? Virgin board like SBS is the usual choice, or use a liner.

For most beauty, wellness and retail brands, 16 to 18 pt SBS is the default, and it’s what we recommend for custom cosmetic boxes. Our quote form also lets you pick 12 pt to 24 pt cardstock, kraft, corrugated and rigid stock, and we’re happy to send material samples.

Finishes look different on each grade too. Foil and embossing are sharpest on smooth SBS. Read embossing vs debossing for more.

Frequently asked questions