For those who might be interested, here is a quote from
a correspondence some time ago:
In The Imperial system, a certain paper size (not a certain paper!) was
measured in lb per ream – but a ream of writing paper contained 480 sheets
and a ream of posters/printing paper contained 516 sheets.
Paper size, then? Well, in Sweden an A4 sized paper is the same,
irrespective of what it is intended for. So was your
Elephant size. But your Royal sheet has one size when it is
intended for writing, and another when meant for posters/
> If it is considered bond, perhaps 90# is very close to the 300 gsm.
This exactly proves why the “Imperial” system for paper identification
is of no use whatsoever! In this particluar case (i.e. Arches), their
300gsm = 140lb and their 185gsm = 90lb.
It is much easier with our Metric system. Irrespective of how small/large a paper
sample you have, you can always tell the proper gsm for it, irrespective
of how many sheets per ream it is sold in and/or how large the base
An example: I have in front of me a very small paper sample.
It measures 97mm * 70mm.
To simplify calculations, we transform those mm into m:
0.097m* 0.070m. Multiply those two figures to get the area of
the sample in square meters = 0.00679sqm.
Weigh the sample: the scale reads 0.54g.
Insert these values into the simple formula
Xgsm = SampleWeightInGrams / SampleAreaInSqm.
X = 0.54 / 0.00679, which equals 80gsm.
Claes in Lund, Sweden