PaperCatalog.com - Formulas, Weights and Measures

Formulas, Weights and Measures

This chapter sets forth formulas and tables that may be used to determine the relationship of various weights, sizes and thicknesses of paper. The text is divided into the following sections.

Basis Weights
Weight of Sheets of Various Dimensions
Bulk of Sheets of Various Weights and Calipers
Economical Use of Paper Sizes
Weight and Square Footage of Rolls

Basis Weights

The weight of a given square area of paper is called its basis weight. This measure could have been established as the weight of 1000 square feet, or some other convenient dimension. In countries using the metric system of measurement, it is shown in grams per square meter.

However, historically, the U.S. paper industry linked the weight to a ream (500 sheets) based on the most suitable size of the type paper involved. For example, the dimension of 17" x 22" (four sheets of 8 1/2 x 11") was established for writing papers. The dimensions used to state the basis weight for various types of paper are as follows:

	Dimensions	Square Inches in one sheet
Writing Paper	17" x 22"	374
Printing Paper	25" x 38"	950
Cover	20" x 26"	520
Printing Bristol	22 1/2" x 28 1/2"	641
Index Bristol	25 1/2" x 30 1/2"	778
Newsprint, Tag & Tissue	24" x 36"	864

The following table shows the equivalent weights of various types of paper based on the respective dimensions used.

	BOND 17" x 22"	PRINTING 25" x 38"	COVER 20" x 26"	BRISTOL 22 1/2" x 28 1/2"	INDEX 25 1/2" x 30 1/2"	NEWSPRINT, TAG & TISSUE 24" x 36"
BOND LEDGER MIMEO DUPLICATOR WRITINGS	13 16 20	33 41 51	18 22 28	22 27 34	27 38 42	30 37 46
	24 28 32	61 71 81	33 39 45	41 48 55	50 58 67	56 64 74
	36 40 44	91 102 112	50 56 61	62 69 75	75 83 92	83 93 102
BOOK OFFSET TEXT	12 16 18	30 40 45	16 21 24	20 27 30	25 32 37	27 36 41
	20 24 28	50 60 70	27 32 38	34 40 47	41 49 57	45 55 64
	31 35 39	80 90 100	43 48 54	54 60 67	66 74 81	73 82 91
	47 59	120 150	65 80	80 100	98 123	109 136
COVER	29 36 43	73 91 110	40 50 60	49 62 74	60 75 90	66 82 100
COVER	47 58 65 72	119 146 164 183	65 80 90 100	80 99 111 124	97 120 135 150	108 134 149 166
MILL BRISTOL	58 70 82	148 176 207	81 97 114	100 120 140	121 146 170	135 162 189
MILL BRISTOL	93 105 117	237 267 296	130 146 162	160 180 200	194 218 243	216 242 269
PRINTING BRISTOL	52 59 71 83 95	133 151 181 211 241	73 83 99 116 132	90 102 122 143 163	109 123 148 173 198	121 137 165 192 219
INDEX BRISTOL	43 53 67	110 135 170	60 74 93	74 91 115	90 110 140	100 122 156
INDEX BRISTOL	82 105	208 267	114 146	140 182	170 220	189 244
TAG	43 54 65	110 137 165	60 75 90	74 93 111	90 113 135	100 125 150
TAG	76 87 109 130	192 220 275 330	105 120 151 181	130 148 186 222	158 180 225 270	175 200 250 300

Weights of Sheets of Various Dimensions

The weight of any size sheet is equal to the ratio of its square area to the square area of the base size for that type paper.

For example:

Assume that the sheet of interest is 70 lb. printing paper in the size 42" x 58".

As noted previously, the size on which the 70 lb. basis weight is based is 25" x 38". The square area of the basic size is equal to 25" x 38" = 950 square inches.

Determine the square area of the sheet of interest
42" x 58" = 2436 square inches.

Divide the square area of the sheet of interest by the square area of the base —
2564 by 950 =2.564

Since the 42" x 58" sheet is 2.564 times bigger than the 25" x 38", it must weigh that much more. Therefore, multiply 70 lbs. by 2.564 to determine the weight of 500 sheets 42" x 58".

70 x 2.564 = 179 lbs.

If the weight for 1000 sheets is desired, multiply the 500 sheet weight by 2.

Tables showing the weight per thousand sheets of the various types of printing and writing papers are provided on the following three pages.

PRINTING PAPERS—Weights Per M Sheets
Basis 25" x 38"

BASIS	30	35	40	45	50	60	70	80	90	100	120	150
17-1/2 x 22-1/2	25	29	33	37	41	50	58	66	75	83	99	124
19 x 25	30	35	40	45	50	60	70	80	90	100	120	150
23 x 29	42	49	56	63	70	84	98	112	126	140	169
23 x 35	51	59	68	76	85	102	119	136	152	170	204
22-1/2 x 35	50	58	66	75	83	99	116	133	149	166	199	249
24 x 36	54	64	72	82	90	110	128	146	164	182	218	272
25 x 38	60	70	80	90	100	120	140	160	180	200	240	300
26 x 40	66	76	88	98	110	132	154	176	198	218	262	328
28 x 42	74	86	100	112	124	148	174	198	222	248	298	372
28 x 44	78	90	104	116	130	156	182	208	234	260	312	390
30-1/2 x 41	78	92	106	118	132	158	184	210	236	264	316	396
32 x 44	88	104	118	134	148	178	208	238	266	296	356	444
33 x 44	92	106	122	138	152	184	214	244	276	306	366	460
35 x 45	100	116	132	150	166	198	232	266	298	332	398	498
36 x 48	108	128	144	164	180	220	254	292	328	364	436	544
38 x 50	120	140	160	180	200	240	280	320	360	400	480	600
41 x 54	140	164	186	210	234	280	326	372	420	466	560	700
44 x 64	178	208	238	266	296	356	414	474	534	592	712	888
35 x 46	102	118	136	152	170	204	238	272	306	338	406
38 x 52	124	146	166	188	208	250	292	332	374	416	500
41 x 61	156	184	212	236	264	316	368	420	472	528	632
42 x 58	154	180	206	230	256	308	358	410	462	512	615
44 x 66	178	208	238	266	296	356	414	474	534	592	712
46 x 69	201	234	267	301	334	400	468	534	602	668	802
52 x 76	250	292	332	374	416	500	582	666	748	832	998

BONDS and WRITING PAPERS—Weights Per M Sheets
Basis 17" x 22"

BASIS	13	16	20	24	28	32	36	40	44
8-1/2 x 11	6.50	8.00	10.00	12.00	14.00	16.00	18.00	20.00	22.00
8-1/2 x 13	7.68	9.44	11.81	14.18	16.54	18.90	21.27	23.63	26.00
8-1/2 x 14	8.26	10.18	12.72	15.26	17.81	20.36	22.90	25.45	28.00
11 x 17	13.00	16.00	20.00	24.00	28.00	32.00	36.00	40.00	44.00
16 x 21	23-1/2	29	36	43	50-1/2	57-1/2	65	72	79
16 x 42	47	58	72	86	101	115	130	144	158
17 x 22	26	32	40	48	56	64	72	80	88
17-1/2 x 22-1/2	27	34	42	51	59	67	76	84	93
17 x 26	31	38	47	57	66	76	85	95	104
17 x 28	33	41	51	61	71-1/2	81-1/2	92	102	112
18 x 23	29	35-1/2	44-1/2	53	62	71	80	89	97-1/2
18 x 46	58	71	89	106	124	142	160	178	195
19 x 24	32	39	49	58-1/2	68-1/2	78	88	98	107
20 x 28	39	48	60	72	84	96	108	120	132
21 x 32	47	58	72	86	101	115	130	144	158
22 x 25-1/2	39	48	60	62	84	96	108	120	132
22 x 34	52	64	80	96	112	128	144	160	176
22-1/2 x 22-1/2	35	43	54	65	76	87	97	108	119
22-1/2 x 34-1/2	54	66	83	99	116	133	149	166	183
22-1/2 x 35	56	67	84	101	118	134	152	168	186
23 x 36	58	71	89	106	124	142	160	178	195
24 x 38	64	78	98	117	137	156	176	196	214
24-1/2 x 24-1/2	42	51-1/2	64	77	90	103	116	128-1/2	141
24-1/2 x 28-1/2	49	60	75	90	105	119-1/2	134-1/2	149-1/2	164-1/2
24-1/2 x 29	49-1/2	61	76	91	106-1/2	122	137	152	167
24-1/2 x 38-1/2	66	81	101	121	141-1/2	161-1/2	182	202	222
24-1/2 x 39	66	82	102	122	144	164	184	204	225
25-1/2 x 44	78	96	120	144	168	192	216	240	264
26 x 34	62	76	94	114	132	152	170	189	208
28 x 34	66	82	102	122	143	163	184	204	224
34 x 44	104	128	160	192	224	256	288	320	352
35 x 45	109	135	168	202	236	270	303	337	371

COVER PAPER—Weights Per M Sheets
Basis 20" x 26"

BASIS	50	60	65	80	90	100	130
20 x 26	100	120	130	160	180	200	260
22-1/2 x 28-1/2	123	148	160	197	222	246	320
23 x 29	128	154	167	205	231	256	334
23 x 35	155	186	201	248	279	310	402
26 x 40	200	240	260	320	360	400	520
35 x 46	310	372	402	496	558	620	804

INDEX BRISTOL—Weights Per M Sheets
Basis 25-1/2" x 30-1/2"

BASIS	90	110	140	170	220
20-1/2 x 24-3/4	117	144	182	222	286
22-1/2 x 28-1/2	148	182	230	280	362
22-1/2 x 35	182	223	284	344	444
25-1/2 x 30-1/2	180	220	280	340	440
28-1/2 x 45	296	364	460	560	724

PRINTING BRISTOL—Weights Per M Sheets
Basis 23" x 35"

BASIS	47	80	100	120
22-1/2 x 28-1/2	134	160	200	240
23 x 35	168	201	252	302
26 x 40	216	260	—	—

TAG—Weights Per M Sheets
Basis 24" x 36"

BASIS	90	100	125	150	175	200	250
22-1/2 x 28-1/2	134	148	186	223	260	297	371
24 x 36	180	200	250	300	350	400	500
28-1/2 x 45	268	296	372	446	520	594	742

Bulk of Sheets of Various Weights and Calipers

The thickness of the sheet can be an important factor in the production, delivery and use of paper. This property influences the strength of the sheet and the height formed when a series of sheets are placed top of each other.

This section presents procedures and tables that may be used to determine the bulk of papers of interest to the reader.

Bulk Determination

Micrometer Reading	Pages Per Inch	Micrometer Reading	Pages Per Inch	Micrometer Reading	Pages Per Inch
.007	1142	.019	420	.031	258
.0075	1066	.0195	410	.0315	254
.008	1000	.020	400	.032	250
.0085	942	.0205	390	.0325	246
.009	888	.021	380	.033	242
.0095	842	.0215	372	.0335	238
.010	800	.022	364	.034