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 = gsm
lb Cover = gsm
GSM to LBS
| gsm | = lb Text |
| = lb Cover |
If you’re still here and interested to find out what lies behind the conversion that we just did for you, read on!
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 catalogue, 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 millimetres 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 1 m2. 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.
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″ |
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.
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 catalogue 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 |
0.095 |
0.0037 |
|
100 |
0.123 |
0.0048 |
|
120 |
0.140 |
0.0055 |
|
140 |
0.160 |
0.0063 |
|
160 |
0.170 |
0.0067 |
|
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 |
0.062 |
0.0024 |
|
105 |
0.095 |
0.0037 |
|
128 |
0.110 |
0.0043 |
|
157 |
0.150 |
0.0059 |
|
200 |
0.180 |
0.0071 |
|
250 |
0.240 |
0.0094 |
|
300 |
0.275 |
0.0108 |
|
350 |
0.410 |
0.0161 |
Matte Art Paper Thickness Charts
| GSM | Thickness for reference (mm) | Caliper for reference (inch) |
|---|---|---|
|
80 |
0.070 |
0.0028 |
|
105 |
0.100 |
0.0039 |
|
128 |
0.125 |
0.0049 |
|
157 |
0.160 |
0.0063 |
|
200 |
0.195 |
0.0077 |
|
250 |
0.234 |
0.0092 |
|
300 |
0.320 |
0.0126 |
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 |
0.47 |
0.0185 |
|
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!