WatchUSeek Watch Forums banner
1 - 20 of 203 Posts

·
Registered
Joined
·
4,888 Posts
Discussion Starter · #1 · (Edited)
I'm sure that some mathematician has worked this out before but I worked out the following ratio system for assessing the appropriate size for a watch on a wrist.

Its pretty simple

1/ Convert wrist size into mm

2/ Divide total wrist size in mm by the size of the watch

eg A 7 inch watch and a 38 mm watch = 178mm divided by 38mm= Ratio of 4.7

This brings me to the controversial part. What is an acceptable ratio? I think using this formula, that an acceptable ratio falls between 4.0 and 5.0. Anything below 4.0 is too big and anything above 5 is too small.

Here is an example using a 44mm watch which should be too big for some with smaller wrists

6.5 inch ( 165 mm) Ratio=3.75 Too big
7.0 inch (178mm) Ratio=4.0 Just ok- acceptable
8.0 inch (203 mm) Ratio=4.6 Great fit


This brings me to interesting observation that wearing a 39 mm watch on a 7 inch wrist has a a very similar Ratio as wearing a 44mm watch on an 8 inch wrist. That is, a ratio of about 4.6.

For reference, here are the conversions for wrist size
6 inch = 152.5 mm
6.5inch = 165mm
7inch = 178mm
7.5inch= 190.5mm
8.0inch = 203mm
8.5 inch = 216mm

I realize I am opening myself up to ridicule for being too analytical but I think it's a pretty useful way to work out a rough guide and obviously does not take into account lug shape etc. What do you think? Has someone worked this out before? Have I got too much time on my hands? Can this concept be improved on?

Cam
 

·
Registered
Joined
·
13,784 Posts
Interesting...

I like it!

I did it for my watches and there may be some truth to it.

My wrist size: 7.25 inches = 185 mm

Ratios:
Seiko Monster - 4.40
Citizen BN0000-04H - 4.51
Bulova Precisionist Claremont - 4.20
Casio G-Shock Mudman - 4.02
 
  • Like
Reactions: MCT

·
Registered
Joined
·
23,771 Posts
Makes sense to me. Let's assume the human wrist is approximately an ellipse with major axis say twice the minor axis (ie twice as wide as thick.)Then assume that the watch diameter is approx the same as the width of the wrist (major axis). Then if you work out the circumference of the ellipse you'll find that the ratio of circumference to major axis is approx. 5. You'd probably want the ratio to be less than that as you don't want the watch to overhang your wrist.
 

·
Registered
Joined
·
241 Posts
I think you have too much time on your hands !!! you need another hobby or part time job !! Haha !
 
  • Like
Reactions: Laso1 and Sodiac

·
Registered
Joined
·
5,144 Posts
I like it.

A 4.5 ratio on my 7 1/8 inch wrists puts me at a 40-41mm watch which is exactly what I prefer.

Furthermore your upper and lower range would equate to 36mm to 45mm, which would be extremes for me.

Well done.
 

·
Registered
Joined
·
4,888 Posts
Discussion Starter · #10 ·
I like it.

A 4.5 ratio on my 7 1/8 inch wrists puts me at a 40-41mm watch which is exactly what I prefer.

Furthermore your upper and lower range would equate to 36mm to 45mm, which would be extremes for me.

Well done.
i was just in the shower where i do all my best thinking and it dawned on me that dividing the total wrist by the ratios 4 and 5 gives you a minimum and maximum ! You just beat me to pointing that out!

eg 7 inch (178mm) gives me a minimum of 35.6mm and a maximum of 44.5 mm
 

·
Registered
Joined
·
2,215 Posts
No No No No!!! It's Length times diameter plus weight over girth............
 

·
Registered
Joined
·
4,956 Posts
I think you can impose certain conditions to account for various watch styles.

1. Dive watches should use bezel diameter should be used instead of case diameter. Some divers have tapered cases so a 44mm Oris Diver wears like a 40mm due to the 40mm bezel.
2. Cushion cased watches should use vertical case length rather than the formal 4 to 10 measurement for case diameter.
 

·
Registered
Joined
·
2,612 Posts
for a 6.5 inch wrist (165.1), the max is 41mm, minimum is 33. The minimum feels a bit small, but maximum is dead on. I prefer anything between 36-41.
 

·
Registered
Joined
·
14,861 Posts
But . . . What about watches that wear bigger or smaller than what their measurements would indicate? ;-)
 

·
Registered
Joined
·
1,450 Posts
What about rectangular watches?
 

·
Registered
Joined
·
4,888 Posts
Discussion Starter · #20 ·
I have a 7.5 wrist and I should prefer 45-50. I dont like it when the case diameter is too small.
According to the theory your range is from 38 to 47.5mm. If you show me a wrist shot of you with a 50mm watch and it looks like it fits, id be happy to to proved wrong. ;-) But you wear what you like, this is just a guide.
 
1 - 20 of 203 Posts
Top