I am looking for a translation of an American ring size 25, I know
this is big but all the charts that I have only go to 15. So what
should the diameter/circumferance be?
Thanks in advance, Neil KilBane, Longford Ireland
Neil KilBane:
One American ring size = .032" (0.813mm).
American size 12 = .843" (21.396mm)
American size 25 = size 12 + (13 X .032" or 13 X 0.813mm) = 1.259"
(31.954mm)
Hope this helps.
Ray Grossman
Ray Grossman Inc.
Manufacturers of Jump Ringer
Neil,
I am looking for a translation of an American ring size 25, I know this is big but all the charts that I have only go to 15. So what should the diameter/circumferance be?
A size 25 would be 1.259" in diameter, 3.956" in circumference.
Ring sizes vary from 0.493" for size 1 to 0.940" for size 15.
Plugging these into a formula for deriving size versus diameter, a
simple slope calculation, would be done thus:
ratio of size to diameter equals ( 15 - 1 ) / ( 0.940 - 0.493 ) =
31.32
diameter of a size 1 is 0.493", so there is an offset of -14.441
diameter = (size - offset) / ratio
Example: diameter of a size “25”
[ 25 - ( - 14.441 ) / 31.32 ] = [ 39.441 / 31.32 ] = 1.259
This is probably more than you wanted to know. The reason I went
through all of this for myself was that I have to use a formula to
figure out how much wire to expect to use for one of my knots, and it
involves the circumference and width of the ring or bracelet. Everyone
uses American sizes, here, so I had to crank out a formula to
translate “size” to “diameter”, which I then incorporated directly
into my overall calculations. If someone tells me they want a ring,
size 11, and it should be half an inch wide, I can set aside 14" for
each complete iteration of the knot and be fairly sure I won’t end up
short. (In practice, of course, it’s better to waste a couple of extra
inches than it is to come up to the last turn and realize I’ve just
wasted the last ten or twenty hours. 
Loren
Here’s a ring size conversion chart. I got it from David Geller, one
helpful guy.
Wayne Emery
USA British French German Japan Swiss
1 B ... ... 1 ...
1 1/4 B-1/2 ... ... ... ...
1 1/2 C ... ... ... ...
1 3/4 C 1/2 ... ... ... ...
2 D 41 1/2 13 1/4 2 1 1/2
2 1/4 D 1/2 ... ... ... ...
2 1/2 E 42 3/4 13 3/4 3 2 3/4
2 3/4 E 1/2 ... ... ... ...
3 F 44 14 4 4
3 1/8 F 1/2 ... ... ... ...
3 3/8 G 45 1/4 ... 5 5 1/4
3 1/2 ... ... 14 1/2 ... ...
3 5/8 G 1/2 ... ... 6 ...
3 3/4 H 46 1/2 ... ... 6 1/2
4 H 1/2 ... 15 7 ...
4 1/4 I 47 3/4 ... ... 7 3/4
4 1/2 I 1/2 ... 15 1/4 8 ...
4 7/8 J 49 ... ... 9
5 J 1/2 ... 15 3/4 9 ...
5 1/8 K 50 ... ... 10
5 3/8 K 1/2 ... ... 10 ...
5 1/2 L 51 3/4 16 ... 11 3/4
5 7/8 L 1/2 ... ... 11 ...
6 M 52 3/4 16 1/2 12 12 3/4
6 1/4 M 1/2 ... ... ... ...
6 1/2 N 54 17 13 14
6 3/4 N 1/2 ... ... ... ...
7 O 55 3/4 17 1/4 14 15 1/4
7 1/4 O 1/2 ... ... ... ...
7 1/2 P 56 1/2 17 3/4 15 16 1/2
7 3/4 P 1/2 ... ... ... ...
8 Q 57 3/4 18 16 17 3/4
8 1/4 Q 1/2 ... ... ... ...
8 1/2 ... ... 18 1/2 17 ...
8 5/8 R 59 ... ... 19
8 7/8 R 1/2 ... ... ... ...
9 ... ... 19 18 ...
9 1/8 S 60 1/4 ... ... 20 1/4
9 3/8 S 1/2 ... ... ... ...
9 1/2 ... ... 19 1/2 19 ...
9 5/8 T 61 1/2 ... ... 20 1/2
10 T 1/2 ... 20 20 ...
10 1/4 U 62 3/4 ... 21 22 3/4
10 1/2 U 1/2 ... 20 1/4 22 ...
10 5/8 V 63 3/4 ... ... 23 3/4
11 V 1/2 ... 20 3/4 23 ...
11 1/8 W 65 ... ... 25
11 3/8 W 1/2 ... ... ... ...
11 1/2 ... ... 21 24 ...
11 5/8 X 66 1/4 ... ... 26 1/4
11 7/8 X 1/2 ... ... ... ...
12 Y 67 1/2 21 1/4 25 27 1/2
12 1/4 Y 1/2 ... ... ... ...
12 1/2 Z 68 3/4 21 3/4 26 28 3/4
12 3/4 Z 1/2 ... ... ... ...
13 ... ... 22 27 ...The diameter listed is the inside dia. for all ring sizes. To get the
length you must add the dia. of the wire, or the thickness or of the
bar stock, to the dia. listed and multiply by Pi or (3.14).
Circumference = Ring Size dia. + wire dia. or bar thickness X 3.14
The reason for this is in bending to a circle the neutral axis which
is in the center does not elongate. You add to the inside dia. 2 X
wire dia./2 to get the neutral axis. Or the inside dia + wire dia. =
neutral axis dia. It would be better to draw a diagram, but I don’t
want to add an attachment.
John Burton - Boy Engineer
Wayne, Thank you for sending along the ring size conversion chart on
Aug 8, from David Geller. I did not realize that there were so many
"size versions" world wide.
I tried to put it into a table format but the problem I have is I
knowing where the divisions are. Example from the list:
7 1/2 P 56 1/2 17 3/4 15 16 1/2
I realize that 6 countries are represented by these numbers but with
only spaces between I am confused as to what goes with what.
Can you provide the list with comma dividers for clarity? I only gave
one example but had the confusion throughout the chart.
Orchid Rules!..Karla from So. California