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Paper Weight Conversion: GSM to LBS

Paper Weight Conversion GSM to LBS

We’d like to give you a helpful explanation of why we measure the thickness of paper by its weight and how to convert gsm measures to lb measures. And we’ve done that in the rest of the page; but we know that you may just need to do a quick conversion from gsm to lb, or vice versa, and crack on with your project. So, if that’s the case, here’s our super-easy online paper weight converter right at the top:

LBS to GSM

lb Text   =  1  gsm

lb Cover   =  1  gsm

GSM to LBS

gsm =  1  lb Text
 =  1  lb Cover

If you’re still here and interested in finding out what lies behind the conversion that we just did for you, read on!

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    Paper Weight and Thickness

    Among several important decisions you’ll need to make when developing a print project—a book, box, card, flyer, booklet, brochure, or catalog, for example—is the and thickness of the paper best suited to your needs. This can get quite complex when a project demands more than one type of paper—for a hardcover book with casing, interior pages, and endpapers, for example. While you can, in principle, measure paper in fractions of millimeters or inches, the printing industry measures paper thickness by its weight.

    We use two weight metrics to describe paper thickness. These are:

    • gsm (grams-per-square-meter)
    • lb (pounds)

    The differences are partly geographical and historical. So, gsm is used everywhere except the USA, where lb is preferred. But let’s quickly explain these measures and then we’ll show you how to convert between them.

    What does ‘gsm’ mean?

    ‘Gsm’ means ‘grams-per-square-meter’.  It’s the weight of a sheet of paper that’s one meter squared. Wood pulp suppliers use weight because they think in terms of bulk. Paper mills measure everything in terms of area. The more wood pulp paper has in it, the heavier it is. A 250-gsm sheet and a 100-gsm sheet are both 1m2.  But one is heavier than the other. Why? Because it’s got more material in it. And that means that, if it’s heavier, it’s almost certainly thicker, too.

    weight in gsm

    What does ‘lb’ mean?

    Standard American English Pounds (lb) also refer to the weight of the paper. It is usually measured as the weight of the uncut size of 500 sheets, known as a “ream” of paper.
    When calculating lb weights the type of paper is important as each has its specific calculation rule depending on whether it’s bond, text, index, Bristol, cover, or another type. Each paper type has a different standard size known as a FOLIO or “parent sheet”. Paper basic weight is measured in pounds (lb) per 500 sheets in the standard size.

    Paper Types or Categories Standard Size
    Bond
    17" × 22″
    Cover
    20" × 26″
    Bristol
    22.5" × 28.5″
    Index
    25.5" × 30.5″
    Text
    25" × 38″
    weight in lb

    As an example, here’s a list of different types of 80 lb paper:

    • 80 lb bond paper: 500 sheets of 17″×22″ bond paper = 80 lb
    • 80 lb cover paper: 500 sheets of 20″ x 26″ cover paper = 80 lb
    • 80 lb Bristol paper: 500 sheets of 22″.5 x 28.5″ Bristol paper = 80 lb
    • 80 lb index paper: 500 sheets of 25.5″ x 30.5″ index paper = 80 lb
    • 80 lb text paper: 500 sheets of 25″ x 38″ text paper = 80 lb

    You may find that the same amount of 80 lb cover paper is heavier than 80 lb text paper. Because 80 lb cover paper is calculated with 20″ x 26″ size paper and 80 lb text paper is calculated with 25″ x 38″ size paper.

    different types of 80 lb paper

    Why Does Paper Weight and Thickness Matter?

    The weight—and therefore the thickness—of the paper you select for your print project makes a huge difference in the following areas:

    • Technical—a certain special technique such as a foil stamp or a die-cut won’t work with all papers, and some books may need heavier paper to suit the binding
    • Aesthetic—a luxury catalog will need a thicker, glossier paper than, say, a comic
    • Practical—the heavier or thicker a paper is the bulk it will add to your product, which could make it unwieldy or if it’s not thick enough, it could be too flimsy and tear or bend too easily
    • Economic—heavier paper costs more to ship and distribute, thinner paper can keep costs down

    So, as you can see, paper thickness is an important decision. And if you’re working with a major international printer such as QinPrinting, then you’ll often need to convert paper weights from gsm to lb so you’re sure that you know what you’re choosing. Well, you’ve got our conversion calculator above to make that much as easy as it can be. But if it’s helpful to know, here’s the mathematical formula that it uses:

    LBS to GSM Formula

    Cover paper and inner paper need different conversion formulas, so make sure to be clear about which you need.

    1 lb of Text paper = 1.48 gsm. So, multiply each pound of text paper by 1.48.

    1 lb of Cover paper = 2.708 gsm. So, multiply each pound of cover paper by 2.708.

    For example:

    80 lb. Text paper =118.4 gsm (80 x 1.48)

    80 lb. Cover paper =216.64 gsm (80 x 2.708)

    Common Lb to Gsm Conversions

    Cover Text
    LB
    GSM
    LB
    GSM
    60
    162.5
    60
    88.8
    70
    189.6
    70
    103.6
    80
    216.6
    80
    118.4
    90
    243.7
    90
    133.2
    100
    270.8
    100
    148.0
    110
    297.9
    110
    162.8
    120
    325.0
    120
    177.6
    130
    352
    130
    192.4

    Gsm to Lb Conversion Formula

    1 gsm = 0.676 lb Text paper. So, multiply each gsm by 0.676.

    1 gsm = 0.369 lb Cover paper. So, multiply each gsm by 0.369.

    For example:

    157 gsm = 106.1 lb Text paper (157 x 0.676)

    157 gsm = 57.9 lb Cover paper (157 x 0.369)

    Common Gsm to Lb Conversions

    Cover Text
    GSM
    LB
    GSM
    LB
    157
    58.0
    80
    54.1
    200
    73.9
    100
    67.6
    250
    92.4
    105
    71.0
    300
    110.8
    120
    81.1
    350
    129.3
    128
    86.5
    140
    94.6
    157
    106.1
    200
    135.2

    Paper Thickness Charts

    Using GSM measurements, paper with higher GSM is thicker. But different types of paper with the same weight are different thicknesses. For example, with the same GSM weight paper, the uncoated type is a little thicker than the coated version. In USA, the measurement of paper thickness is also called ″Caliper″ and 1 inch=25.4mm.

    Offset Paper Thickness Charts

    GSM Thickness for reference (mm) Caliper for reference (inch)
    80
    0.097
    0.0038
    100
    0.118
    0.0046
    120
    0.140
    0.0055
    140
    0.160
    0.0063
    180
    0.200
    0.0079
    250
    0.335
    0.0132

    Gloss Art Paper Thickness Charts

    GSM Thickness for reference (mm) Caliper for reference (inch)
    80
    0.065
    0.0026
    105
    0.086
    0.0034
    128
    0.105
    0.0041
    157
    0.136
    0.0053
    200
    0.178
    0.0070
    250
    0.225
    0.0088
    300
    0.270
    0.0106
    350
    0.410
    0.0161

    Matte Art Paper Thickness Charts

    GSM Thickness for reference (mm) Caliper for reference (inch)
    80
    0.072
    0.0028
    105
    0.090
    0.0035
    128
    0.110
    0.0043
    157
    0.140
    0.0055
    200
    0.200
    0.0079
    250
    0.250
    0.0098
    300
    0.285
    0.0112

    Coated One Side Paper Thickness Charts

    GSM Thickness for reference (mm) Caliper for reference (inch)
    210
    0.30
    0.0118
    250
    0.35
    0.0138
    300
    0.41
    0.0161
    350
    0.50
    0.0197
    400
    0.55
    0.0217

    Grey Board Thickness Charts

    Thickness for reference (mm) GSM Caliper for reference (inch)
    1
    600
    0.0394
    1.5
    900
    0.0591
    2
    1200
    0.0787
    2.5
    1500
    0.0984
    3
    1800
    0.1181

    Grey Board (One Side White) Thickness Charts

    Thickness for reference (mm) GSM Caliper for reference (inch)
    1
    700
    0.0394
    1.5
    1000
    0.0591
    2
    1300
    0.0787
    2.5
    1600
    0.0984
    3
    1950
    0.1181

    Talk to Us!

    The choice of paper affects the quality and impact of the finished printed product, the design process, and the price. When you have a print project in mind, the best thing to do is to talk to us first. With over 25 years’ experience under our belts, the latest offset printing technology at our fingertips, a vast range of paper options available, and a genuine commitment to customer service, we’ll be happy to give you the best advice to help you choose the perfect paper for both your print project and your budget. Get in touch today for an informal chat or a no-obligation quote. On request, we can also send you our comprehensive paper samples manual. It’s free; you only pay the cost of mailing it to your chosen address. We can’t wait to work with you!

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