GSM refers to grams per square meter and allows one to assess the density and hence quality to the touch of various paper types. To find the GSM of a ream containing 500 sheets of a given size in centimeters and kilogram wight per ream the following calculation is used:

Weight per ream * 20,000/(length * width)

Standard GSM/Weights for sheets 56*76 cm size:

40 kg ream = 188 GSM               100 GSM = 21.29 kg

60 kg ream = 282 GSM               200 GSM = 42.58 kg

70 kg ream = 329 GSM               300 GSM = 63.87 kg

80 kg ream = 376 GSM               400 GSM = 85.16 kg