Paper weight

Paper weight in gsm and in American basis weights, with the conversion and the trap it contains.

80 lb paper is two different papers

80 lb text is 118 gsm. 80 lb cover is 216 gsm. One is a brochure page and the other is a business card, and they are 1.83 times apart in weight while carrying the same number on the label.

The reason is that an American basis weight is the weight of 500 sheets at that grade's basis size, and the basis sizes are different: bond is measured at 17 × 22 inches, text at 25 × 38, cover at 20 × 26. Five hundred sheets of a bigger sheet weigh more for the same paper, so the number goes up without the paper changing. A pound figure means nothing without its grade.

GSM has no such problem. It is grams per square metre — one number, no grade, no basis size, the same everywhere. If you are specifying paper and have the choice, specify gsm.

GSM to pounds, every grade

gsm	Bond	Text	Cover	Index	Tag	Bristol	Typical use
60	16 lb	41 lb	22 lb	33 lb	37 lb	27 lb	Thin book paper and economy copier stock
70	19 lb	47 lb	26 lb	39 lb	43 lb	32 lb	Budget office paper and mass-market paperback pages
75	20 lb	51 lb	28 lb	41 lb	46 lb	34 lb	The North American office default, sold as 20 lb bond
80	21 lb	54 lb	30 lb	44 lb	49 lb	36 lb	The world standard for office paper
90	24 lb	61 lb	33 lb	50 lb	55 lb	41 lb	A step up from copier paper, used for letterheads and documents meant to be handed over rather than filed
100	27 lb	68 lb	37 lb	55 lb	61 lb	46 lb	Quality stationery and the inner pages of good brochures
120	32 lb	81 lb	44 lb	66 lb	74 lb	55 lb	Heavy letterhead and single-sheet flyers
150	40 lb	101 lb	55 lb	83 lb	92 lb	68 lb	Poster and flyer weight
170	45 lb	115 lb	63 lb	94 lb	104 lb	78 lb	Magazine covers and premium flyers
200	53 lb	135 lb	74 lb	111 lb	123 lb	91 lb	Light card for folders, presentation covers and the thinner end of postcards
250	66 lb	169 lb	92 lb	138 lb	154 lb	114 lb	Postcard and invitation weight, and the minimum most printers accept for anything posted without an envelope
300	80 lb	203 lb	111 lb	166 lb	184 lb	137 lb	The standard business card weight, and the usual choice for premium invitations
350	93 lb	236 lb	129 lb	194 lb	215 lb	160 lb	Heavy business cards, tags and light packaging

Greyed figures are outside the range that grade is sold in — the arithmetic holds, but nobody makes 203 lb text paper.

The basis sizes

Grade	Basis size	500 sheets	What it is
Bond / Writing	17 × 22 in	120.6 m²	Office copier paper, letterheads and business stationery.
Text / Book	25 × 38 in	306.5 m²	Book pages, brochures, magazine interiors and flyers.
Cover	20 × 26 in	167.7 m²	Business cards, book covers, postcards and folders.
Index	25.5 × 30.5 in	250.9 m²	Index cards, tabbed dividers and stiff record cards.
Tag	24 × 36 in	278.7 m²	Tags, tickets and hanging labels.
Bristol	22.5 × 28.5 in	206.9 m²	Drawing board, presentation card and heavy stock.

Common weights by grade

Bond / Writing — 16 lb (60 gsm) · 20 lb (75 gsm) · 24 lb (90 gsm) · 28 lb (105 gsm) · 32 lb (120 gsm) · 36 lb (135 gsm)

Text / Book — 50 lb (74 gsm) · 60 lb (89 gsm) · 70 lb (104 gsm) · 80 lb (118 gsm) · 100 lb (148 gsm)

Cover — 65 lb (176 gsm) · 80 lb (216 gsm) · 100 lb (270 gsm) · 130 lb (352 gsm)

Index — 90 lb (163 gsm) · 110 lb (199 gsm) · 140 lb (253 gsm)

Tag — 100 lb (163 gsm) · 125 lb (203 gsm) · 150 lb (244 gsm)

Weight is not thickness

Two sheets at the same gsm can differ noticeably in thickness, because gsm measures mass and thickness depends on how much air is in the sheet. An uncoated bulky stock is thicker than a compressed glossy one at the same weight — sometimes by half again. Printers quote thickness separately, in microns or in points, and a paper specified only by gsm can still arrive feeling wrong.

Paper sizes · Unit converters