The thickness of a sheet of watercolor paper is measured by weight. The greater the weight, the thicker the sheet. It is measured either in pounds per ream (lb) or grams per square meter (gsm). This scale may be helpful to you:
Watercolor
22″ x 30″ (Sheet size)
500 (Sheets/ream)
2292 (Sq. ft./ream)
GSM (metric)Grams per square meter
Pounds
75
85
95
105
115
190
250
300
335
355
365
435
620
35
40
45
49
54
90
117
141
157
167
171
204
300
GSM = Grams [...]
