Understanding the Different Weights of Binding Cover Stocks

Our sales staff at MyBinding.com are commonly asked about the thicknesses of the binding covers that we carry on our site. Unfortunately, understanding the way that cover stocks are measured can be somewhat tricky since several different measuring standards are used. This article is designed to give you a quick overview of the different measuring standards used for the cover stocks that we carry.

  • Most of the clear binding covers and poly binding covers available from MyBinding.com are measured in Mil’s (also sometimes referred to as gauge). At first glance, it might appear that this is a measurement in millimeters. However, one mil actually equals 0.001 inch. Thus a 10mil clear cover has a caliper measurement of 0.010 inches and a 19mil poly cover has a caliper measurement of 0.019 inches.
  • The regency composition / leatherette covers that we carry are measured in points rather than mils. For instance, most of the regency composition / leatherette covers that we carry are rated as 17pt covers. Each point is equal to 0.001 inches (the same as mil’s or gauge). Thus the 17pt covers that we carry have a caliper measurement of approximately 0.017 inches.
  • Most of the paper covers that we carry are measured in weights. For instance, GBC’s linen weave paper covers are made from 80lb cover stock. This measurement is the actual weight of 500 master sheets (25” x 38” in size for cover stocks). Depending on the type of paper you use, the weight is based on different master sheet sizes, making it very difficult to compare weights of bond paper with offset paper or index stock with cover stock. However, to give you an idea, 80lb cover stock is approximately equivalent to 9.5 Mils, 90lb cover stock is approximately equivalent to 10 Mils and 100lb cover stock is approximately equivalent to 11 Mils.

We know that this can all be a little bit confusing but to help you compare apples to apples, here is a quick reference chart that shows several of the different types of paper and their approximate equivalents. If you have any other questions, please feel free to comment below or contact us at sales@mybinding.com or 1-800-944-4573. 

Paper Weights Table

Bond
Ledger

Offset
Text

Cover

Tag

Index

Points

*Caliper
(inches)

millimeters

Metric
(grams/sq meter)

Equivalent

16

40

22

37

33

3.2

.0032

0.081

60.2 gsm

Weight

18

45

24

41

37

3.6

.0036

0.092

67.72 gsm

20

50

28

46

42

3.8

.0038

0.097

75.2 gsm

24

60

33

56

50

4.8

.0048

0.12

90.3 gsm

28

70

39

64

58

5.8

.0058

0.147

105.35 gsm

29

73

40

62

60

6

.0060

0.152

109.11 gsm

31

81

45

73

66

6.1

.0061

0.155

116.63 gsm

35

90

48

80

74

6.2

.0062

0.157

131.68 gsm

36

90

50

82

75

6.8

.0068

0.173

135.45 gsm

39

100

54

90

81

7.2

.0072

0.183

146.73 gsm

40

100

56

93

83

7.3

.0073

0.185

150.5 gsm

43

110

60

100

90

7.4

.0074

0.188

161.78 gsm

44

110

61

102

92

7.6

.0076

0.193

165.55 gsm

47

120

65

108

97

8

.0078

0.198

176.83 gsm

53

135

74

122

110

9

.0085

0.216

199.41 gsm

54

137

75

125

113

9

.009

0.229

203.17 gsm

58

146

80

134

120

9.5

.0092

0.234

218.22 gsm

65

165

90

150

135

10

.0095

0.241

244.56 gsm

67

170

93

156

140

10.5

.010

0.25

252.08 gsm

72

183

100

166

150

11

.011

0.289

270.9 gsm

76

192

105

175

158

13

.013

0.33

285.95 gsm

82

208

114

189

170

14

.014

0.356

308.52 gsm

87

220

120

200

180

15

.015

0.38

312 gsm

105

267

146

244

220

18

.0175

0.445

385.06 gsm