grams/square meter to pounds/ream
by Cathy on 06/14/05 at 14:23:37

Any help would be appreciated.  (A ream is 432,000 square inches)

Re: grams/square meter to pounds/ream
by Robert Fogt on 06/16/05 at 06:42:20

There is no direct conversion between the density of paper and pound weight. They are just measuring different things.

A good place for paper information is here:
http://palimpsest.stanford.edu/don/don.html

They do have a Feedback form, so perhaps they can directly answer your question.

Re: grams/square meter to pounds/ream
by essbee on 07/11/05 at 18:40:39

Here is an interesting relationship that might me useful.

1 ream (500 sheets) of 8.5" x 11" has a total area of 46 750. square inches.

In metric:
1 ream (500 sheets) is  216mm x 279mm = 30.132 square meters.

Now the ream of paper I have is 24 lb paper.  It also gives the weight as 90 grams / square meter.

24 lbs = 10 886.2169 grams

So I wanted to know how many sheets of 24 lb paper actually weigh 24 pounds ...

10 886.2169 grams / (90 grams / sq meter) = 120.957965 sq meters.

120.957965 sq meters / (0.216 x 0.279) = 2007.13469 sheets.

That means that ABOUT 4 reams of paper actually weigh 24 pounds.

It's not exact because "24 lbs" is a nominal size (that's the name we call it) not an exact size.  Like we call a standard piece of lumber a two by four (meaning 2 inches by 4 inches) but the actual measurement is not 2.00" x 4.00".

I'm going to guess that there is a historic explaination to why paper is measured that way.

24 lb paper means "24 pounds per 187000 square inches.

I thought that was Cool !

Martin

Re: grams/square meter to pounds/ream
by Wilfred on 10/07/05 at 20:02:32

There is an easy way to understand paper sheet size, and paper weight.

The sheet size 8.5 inches x 11 inches is nearly the same as the A4 sheet size which is part of the metric system.

The metric system of page sizes is based on the area of one square metre for a sheet which is described as size A0.

If you fold a sheet of A0 paper in half, you get a sheet size of A1, where each A1 page has an area of half a square metre.

If you fold an A1 page in half, you get two pages with sheet size A2, and each page one quarter of a square meter in area, or 4 sheets per square meter.

If you keep repating this folding process, you get to size A4 (which is approximately the size of "American quarto").  If you follow through the above explanation, you will see that there are exactly 16 sheets of A4 paper to a square meter of paper.

Now for the weight of paper, for example 80gsm.  (This paper is commonly used for photocopy machines).  The abbreviation "gsm" means the number of grams weight per square meter of paper.

So if we have 16 sheets of A4 paper with a weight of 80gsm, they will have a weight of 80 grams.

A ream of paper is 500 sheets.  It does not matter what size those sheets are, but there are always 500 sheets in a ream.

So a ream of 80gsm A4 paper would weigh:
(500 / 16) * 80 = 2500 grams, (or approx 5.5 pounds).

The size of an A4 sheet, 210mm by 297mm
(or 8.27 inches by 11.69 inches)
may puzzle many people.

The adavantage of this metric series of page sizes, A0 - A1 - A2 - A3 - A4 - A5, is that every size maintains the same ratio of width and height.

If the width of a page is "w", and the height of a page is "h", then the relationship of "w" and "h" is given by the formula:
h = w * 1.4142
(where 1.4142 is the square root of 2)  

You may be interested in information on the following websites:

http://www.canon.com.au/products/papers/paper_bw_laser/624.html

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdrawingprintingpaperkindclasstopic.asp

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