Adeodatus Posted January 18, 2012 Report Share Posted January 18, 2012 We almost always buy watches online and sometimes upon receiving the watch you realize it is too big for your wrist or too small. Knowing the diameter works well enough, but we all have different wrists of different shapes, so I've been thinking of a more (pseudo) scientific way to tell if the watch you are buying will fit your wrist. This is what I've been thinking about: j=a/b a = your wrist perimeter b = your wrist width j = your wrist constant k=(x+((y-x)/2))/2 x = watch diameter y = watch width including the lugs k = your watch constant Q=j/k 0.12<Q<0.15 - the watch is right for you Q<0.12 - the watch is too large for your wrist Q>0.15 - the watch is too small for your wrist I've tried this formula with a few watches I have and it seems to work. Can you please help me verify this (if you are interested of course). Man... I have too much free time on my hands 1 Quote Link to comment Share on other sites More sharing options...
seeaye Posted January 18, 2012 Report Share Posted January 18, 2012 why do you think that k should be that? rather than just y/x or x/y.. would just give you a different normal range for Q?great thought though I like the way u think Quote Link to comment Share on other sites More sharing options...
ninjagaiden Posted January 18, 2012 Report Share Posted January 18, 2012 I would try and squeeze a PI in there somewhere, given that wrist perimeter and wrist surface are related! Of course, you would need to perform a regression analysis of your formula by being given hundreds of different gen watches to try out and see how well they conform to your formula. Then, to validate your regression analysis, you would need to be given hundreds of rep watches and repeat the exercise. Man - I feel a grant application coming along. <tongue firmly in cheek> N Quote Link to comment Share on other sites More sharing options...
Bardamu Posted January 18, 2012 Report Share Posted January 18, 2012 (edited) I'm not sure that we can define a formula that could calculate accurately if the size of the watch will fit with our wrist. Your formula is a good start, but you cannot be sure before you try it on. Other points, more difficult to estimate, have to be taken into account. I have two points in mind : - Do you use to wear large watches or not ? This will be important to decide if you feel comfortable or not with it. - What is the weight and thickness of the watch ? This point can be important. A large and flat watch can be wore easily. But if the same case is very thick and heavy (diver watch like DSSD, for instance), you will feel it very different. Each time you move your hand, the watch move much more than a flat one. So, at the end of the story, I would say that my personal formula would be "you like it ? take it ! " Paul PS : I just see that this is my 69th post. Coooooooooooooool ! Edited January 18, 2012 by Bardamu Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted January 18, 2012 Author Report Share Posted January 18, 2012 ... given hundreds of different gen watches to try out .. Then... you would need to be given hundreds of rep watches.. Damn, I like the sound of it! Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted January 18, 2012 Author Report Share Posted January 18, 2012 I'm not sure that we can define a formula that could calculate accurately if the size of the watch will fit with our wrist. Your formula is a good start, but you cannot be sure before you try it on. Other points, more difficult to estimate, have to be taken into account. I have two points in mind : - Do you use to wear large watches or not ? This will be important to decide if you feel comfortable or not with it. - What is the weight and thickness of the watch ? This point can be important. A large and flat watch can be wore easily. But if the same case is very thick and heavy (diver watch like DSSD, for instance), you will feel it very different. Each time you move your hand, the watch move much more than a flat one. So, at the end of the story, I would say that my personal formula would be "you like it ? take it ! " Paul Absolutely, I need to add +/- 0.01 for "likability" Quote Link to comment Share on other sites More sharing options...
Jmabshir Posted January 18, 2012 Report Share Posted January 18, 2012 Pretty interesting, I calculated and found that for most of my watches i'm at either of the boundaries you have exactly (.12 and .15) with the PAM111 at Q=.12. Quote Link to comment Share on other sites More sharing options...
TeeJay Posted January 18, 2012 Report Share Posted January 18, 2012 I'm no good with math, but I really like that idea Quote Link to comment Share on other sites More sharing options...
Ronin Posted January 18, 2012 Report Share Posted January 18, 2012 Please clarify your terminology. What is a wrist perimeter? Width? I think I know what you mean, but it is a bit unclear. You also mention watch width with lugs, so I assume you are talking about a 12-6 'length' measurement and not a 9-3 'width' measurement. Should crown width be considered? Put this into an Excel spreadsheet once we shore up the definitions. Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted January 19, 2012 Author Report Share Posted January 19, 2012 Perimeter is the wrist size ie 7", 6 1/2" etc in mm Wrist width is the actual width of your wrist The watch width is indeed the 12-6 measurment Here is the excelwatch_size_formula.xls 1 Quote Link to comment Share on other sites More sharing options...
Ronin Posted January 20, 2012 Report Share Posted January 20, 2012 Excellent. The Excel Spreadsheet worked great. Proved what I already knew, that Rolex 40mm watches are perfect for me. Quote Link to comment Share on other sites More sharing options...
wiesn089 Posted January 20, 2012 Report Share Posted January 20, 2012 Thanks, that's very interesting! I checked some watches and it seems to be almost spot on for me. I adjusted the values a little bit to fit my taste (<0.13 too large) since a Speedmaster is about the biggest I am comfortable to go and it sits at 0.13, but that's about it, great work, thanks! Quote Link to comment Share on other sites More sharing options...
frankt Posted January 20, 2012 Report Share Posted January 20, 2012 Dial size vs overall case size needs to be considered also...For instance compare a Big Pilot to a Ploprof to see what I mean!! Quote Link to comment Share on other sites More sharing options...
Ronin Posted January 21, 2012 Report Share Posted January 21, 2012 Other Variables: -Dial Color (White wears Bigger, Black wears smaller) -Case Thickness (Thicker / Top heavy wear bigger. Slimmer (on a large diameter) wear smaller) Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted January 21, 2012 Author Report Share Posted January 21, 2012 You're probably right, Ronin. The only question is how to sum it up mathematically, especialy the colour. Quote Link to comment Share on other sites More sharing options...
Nanuq Posted January 21, 2012 Report Share Posted January 21, 2012 This is fine pre-purchase. For post-purchase empirical analysis, I believe one can make the observation that WD ~ k•(1/[Mp]) where WD is watch diameter, k is a constant and Mp is phallic mass. Quote Link to comment Share on other sites More sharing options...
RobT Posted January 22, 2012 Report Share Posted January 22, 2012 wow, surprised someone came up with a formula! Ill give it a try Quote Link to comment Share on other sites More sharing options...
OldCorvette Posted January 27, 2012 Report Share Posted January 27, 2012 (edited) Unfortunately, computing this formula sounds like the perfect job for.... the Casio Data Bank !! Seriously, If you: 1. Know the width of your wrist in Millimeters 2. Find the Lug to Lug width specs and case diameter specs of the watch you are considering You're at 95% of this formula without relying on a Casio. Edited January 27, 2012 by OldCorvette Quote Link to comment Share on other sites More sharing options...
alexfilipov Posted February 2, 2012 Report Share Posted February 2, 2012 This formula is indeed ingenious and works for me. Tested it on all my watches. Million thanks! Now I know I need a 42 mm Omega PO Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted February 2, 2012 Author Report Share Posted February 2, 2012 Great! Glad you find it useful, mate. Get that PO, you won't regret it. Quote Link to comment Share on other sites More sharing options...
SlipperyPete Posted February 3, 2012 Report Share Posted February 3, 2012 What's the best way to find the lug to lug width? Say, I'm deciding between a 42mm & 45.5mm Planet Ocean, how can I find the width? This would be a sweet online calculator if there was a database with watch specs! Quote Link to comment Share on other sites More sharing options...
Adeodatus Posted February 3, 2012 Author Report Share Posted February 3, 2012 Omega PO 42 lug to lug size: 47.7 mm Omega PO 45.5 lug to lug size: 52mm Quote Link to comment Share on other sites More sharing options...
horolophile Posted February 19, 2013 Report Share Posted February 19, 2013 (edited) Alas there's a problem with the math here: Imagine for a moment your wrist was perfectly round. Now, for the formula as stated: a = circumference ( c ) b= diameter ( d ) j = circumference/diameter Now, we know the classic 'c = 2πr', or alternately 'c = πd', which can be rearranged to 'c/d = π'. So, were your wrist a perfect circle, j would *always* = π, no matter how big or small your wrist actually *is*. Now, true, nobody's wrist is perfectly circular, but in measuring the equivalent of 'c/d' (in our case 'a/b') we are only measuring how 'out of true', or how 'flat' someones wrist is, and the resultant 'j' tells us nothing about the actual size of the wrist, which is kinda' important when determining watch size. Just my 2¢ Pax -Aaron Edited February 19, 2013 by horolophile Quote Link to comment Share on other sites More sharing options...
horolophile Posted February 19, 2013 Report Share Posted February 19, 2013 Alas there's a problem with the math here: Imagine for a moment your wrist was perfectly round. Now, for the formula as stated: a = circumference ( c ) b= diameter ( d ) j = circumference/diameter Now, we know the classic 'c = 2πr', or alternately 'c = πd', which can be rearranged to 'c/d = π'. So, were your wrist a perfect circle, j would *always* = π, no matter how big or small your wrist actually *is*. Now, true, nobody's wrist is perfectly circular, but in measuring the equivalent of 'c/d' (in our case 'a/b') we are only measuring how 'out of true', or how 'flat' someones wrist is, and the resultant 'j' tells us nothing about the actual size of the wrist, which is kinda' important when determining watch size. Just my 2¢ Pax -Aaron Just as a quick example: I've got big wrists, and (roughly) have a = 19.5, and b = 7, so my j = 2.79. Meanwhile, my daughter has a = 17.25, and b = 5.75, so her j = 3.00. Now, to compare to one of the watches above (the 45.5mm Planet Ocean, since I have one to test with) which ends up having k = 24.38 once you crunch the numbers. For me, 2.86/24.38 = .11, so this watch is too big for me (according to the formula) For my daughter, 3.00/24.38 = .12, so the same watch fits her significantly smaller wrists (again, according to the formula). Having just tried the watch on, and then having her try it on, I assure you, it looks just about perfectly sized on me and laughably large on her. Quote Link to comment Share on other sites More sharing options...
martijnp Posted February 20, 2013 Report Share Posted February 20, 2013 Perimeter is the wrist size ie 7", 6 1/2" etc in mm Wrist width is the actual width of your wrist The watch width is indeed the 12-6 measurment Here is the excel Thanks that just looks great! Will try it when I'm back home Quote Link to comment Share on other sites More sharing options...
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