For example, one eBay Guide (written by sugar_creek_leather), first makes a correct statement (that the "ounce" rating of a piece of leather is based upon how much one square foot of it weighs). But then he goes on to illustrate this by claiming that (therefore) a piece of 2oz leather that's 10 sq.ft. in size would weigh 10 ounces on a scale. He shows his calculation as: "10 ft X 2oz = 10 ounces".
That's just plain wrong -- mathematically wrong, which should be obvious to anyone who remembers their 3rd Grade multiplication tables.
Here on planet Earth, 10 x 2 = 20, (not 10) !!!. So that 10 ft piece of leather placed on a scale would actually weigh 20 ounces.
Can you spell MULTIPLY, boys & girls?
Another error frequently seen in conversion charts is the claim that there is equivalence between leather weights (in ounces), and leather thickness (in 64ths of an inch). You may encounter conversion charts which claim that 1oz leather = 1/64" thickness, and 2oz = 2/64", and 3oz = 3/64", etc. That is also wrong. According to such charts, 11oz leather is 11/64" thick; but in fact, 11oz leather = 4.4mm = 0.1732 inches thick -- which equals an uncommon fraction, 13/75" (which you'll never find on your ruler or tape measure). [Psst -- quickly, who can tell me... is 13/75" larger or smaller than 3/8" ? I.E., conversions from ounces to weird fractions like that are not very meaningful to those of us who think in terms of inches and feet, and the little marks between them on a ruler. ]
Going in the other direction (from a familiar fraction of an inch, to ounces), 11/64" leather thickness is NOT equal to 11oz weight. 11/64" = 0.1719 inches = 4.37mm thickness, which would weigh in at 10.91 oz. Which is not 11oz. Not quite. Close perhaps, but no cigar today for whoever published that error in their conversion table, boys & girls.
The purpose of this guide is to finally publish some *correct and accurate* Leather Weight Conversions information -- first converting from leather weight in ounces to mm, then to inches, and then going in the reverse direction, from inches to ounces.
Tables for the latter type of conversion, starting with thickness measurements in common fractions of an inch, then converting that to mm and then to weight in ounces, are uncommon (or perhaps non-existent) but they are needed. For many Americans at any rate, who use rulers marked in inches, not centimeters, and who (for better or worse) are more familiar with common fractions such as 1/16" or 3/32" than with the decimals and millimeters of the metric system (or with "weird" fractions, such as the 13/75" from the above illustration), this chart should be helpful.
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