Thread: razor sizing

Can anyone explain why razors are only sized in 8ths and 16ths of an inch. Anything else would be sized to the lowest common denominator, for example, a 4/8 is 1/2, a 6/8 is 3/4 and 8/8 is 1/1 or 1 inch.
I can understand the 16ths as they are between the 8ths, I included them so I didn't get posts saying that 16ths were used, so my question is why are 8ths of an inch the lowest denominator used?

Not sure when the metric system came to Europe. I'm guessing ....... just guessing, the inch system was universal back then, and using eighths and sixteenths as a standard was convenient.

Let me give you an example from another industry


12 gauge
20 gauge
16 gauge
10 gauge

This is a carry over from a very old system of measurement, in fact many shooters can't even tell you what the system is, but we have never varied from it and continue to use it today..

Want to have even more fun try and figure out Shot sizes in the shells

I think that keeping them all in 1/8's helps for comparison quickly. It's the common unit in the razor industry.

I work in a machine shop. 0.5 inches is read as "five hundred thousandths" .0005 is "half a thousandth" or "five tenths" since .001 is the common unit for the work we do.

In archery, aluminum arrows are measured in 64ths of an inch.

Like HNSB said, I think it's just an established interval and way to compare, like wood thicknesses being measured in quarters (3/4, 4/4, 5/4, 6/4...12/4). It's not actually 5/4 of an inch thick when dry, it's just close and bigger than a 4/4 piece of lumber and less than a 6/4 piece.

Originally Posted by K37

Like HNSB said, I think it's just an established interval and way to compare, like wood thicknesses being measured in quarters (3/4, 4/4, 5/4, 6/4...12/4). It's not actually 5/4 of an inch thick when dry, it's just close and bigger than a 4/4 piece of lumber and less than a 6/4 piece.

Yeah, these examples are a point of reference. As in a two by four. In the real world a 2x4 is actually 1 3/4 x 3 3/4 IIRC. Just a point of reference so we can all be on the same page.

Originally Posted by gssixgun

Let me give you an example from another industry


12 gauge
20 gauge
16 gauge
10 gauge

This is a carry over from a very old system of measurement, in fact many shooters can't even tell you what the system is, but we have never varied from it and continue to use it today..

Want to have even more fun try and figure out Shot sizes in the shells

The number of lead balls the Diameter of the barrel that equals 1 lb.

Originally Posted by HNSB

I think that keeping them all in 1/8's helps for comparison quickly. It's the common unit in the razor industry.

I work in a machine shop. 0.5 inches is read as "five hundred thousandths" .0005 is "half a thousandth" or "five tenths" since .001 is the common unit for the work we do.

In archery, aluminum arrows are measured in 64ths of an inch.

The ease of comparison makes sense, I just found the lack of lower (or would it be higher) denominations unusual.
I don't really use imperial anymore, though I did learn it at school, and used it for quite a while, particularly when I worked in a builder's merchants, timber in The UK was always sold in imperial sizes, though that may have changed over the last 7 years.