03072006, 12:29 PM  #1 
Join Date: Jan 2006

Calculating Weight in Relation to Height
having a brain cramp and I've seen this posted on various RPG forums over the years.
I'm trying to get a rough formula to calculate a persons weight based on their height. so a 6 foot, 200 lb man growing 1 foot will be 7 feet tall and approx ? same with shrinking by the same amount. thanks. 
03072006, 01:29 PM  #2 
Join Date: Sep 2004
Location: Lexington, KY

Re: Calculating Weight in Relation to Height
Assuming proportionate change in all three dimensions, growing 1 foot will result in a weight of (7/6)^3 * 200 lbs., or roughly 318 lbs; shrinking 1 foot will result in a weight of (5/6)^3 * 200 lbs., or roughly 116 lbs.
Last edited by thastygliax; 03072006 at 01:32 PM. 
03072006, 02:33 PM  #3 
Join Date: Feb 2005
Location: Berkeley, CA

Re: Calculating Weight in Relation to Height
Note that typically creatures do not grow in all dimensions equally. For a human, it's closer to the 2.5 power of height

03072006, 03:44 PM  #4 
Join Date: Jan 2005
Location: Stuttgart, Germany

Re: Calculating Weight in Relation to Height
And of course, you could go by BMI (Body Mass Index).
BMI is calculated by dividing a person's weight (in kilograms) by his or her height (in meters, squared). BMI can also be calculated by multiplying weight (in pounds) by 705, then dividing by height (in inches) twice. So a 6 foot, 200 lb man has a BMI of (200*705/72^2) = 27.2 (clinically overweight) A 7 foot man with a BMI of 27.2 would weigh (27.2*84^2)/705 = 272 lbs A 5 foot man with a BMI of 27.2 would weigh (27.2*60^2)/705 = 139 lbs 
03072006, 04:05 PM  #5  
Join Date: Jan 2006

Re: Calculating Weight in Relation to Height
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03072006, 04:18 PM  #6  
Join Date: Jan 2005
Location: Stuttgart, Germany

Re: Calculating Weight in Relation to Height
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Just offering a formula which is tailor made for human body masses at different heights. You wouldn't need a table, you'd just have to calculate BMI for base form, then derive final weight as I showed above, just two very basic calculations. Then again, you should just go with whatever you find easier to use, especially if pseudorealism isn't a big issue.
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Violence, naked force, has settled more issues in history than has any other factor, and the contrary opinion is wishful thinking at its worst. RAH 

03082006, 07:22 AM  #7  
Join Date: Jun 2005

Re: Calculating Weight in Relation to Height
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If you're assuming height and weight change within a single species, Homo sapiens, you might want to use the BMI. You convert height to meters (or take height in meters, if you're not an American); square it; and multiply by the BMI, where 25 is a typical value for humans. Weight increases as the square of height. So you have a height increase by a factor of 7/6; you take weight increase as the square of that: 200 x (7/6) x (7/6) = 272. If you simply scale up geometrically, so that all body proportions are unchanged, then you take weight increase as the cube of height increase: 200 x (7/6)^3 = 317. If you assume interspecies size changes, the actual scaling law for land animals has body weight going nearly as the fourth power of height (perhaps because the formula for buckling of a column gives this result): 200 x (7/6)^4 = 370. By using this you are reflecting the observable fact that bigger animals tend to have thicker legs. 

03082006, 10:47 AM  #8  
Join Date: Jan 2005
Location: Stuttgart, Germany

Re: Calculating Weight in Relation to Height
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(I definitely need to work on my clarity, possibly my tact too, though I don't know why a clinical observation would be taken the wrong way.)
__________________
Violence, naked force, has settled more issues in history than has any other factor, and the contrary opinion is wishful thinking at its worst. RAH 

03092006, 12:03 AM  #9  
Join Date: Jun 2005

Re: Calculating Weight in Relation to Height
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03092006, 12:14 AM  #10  
Banned
Join Date: Jan 2005
Location: Gothenburg, Sweden

Re: Calculating Weight in Relation to Height
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