Calculating Weight in Relation to Height

[Gadrin]

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.

[thastygliax]

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.

[Anthony]

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

[Ze'Manel Cunha]

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

[Gadrin]

Originally Posted by Ze'Manel Cunha

So a 6 foot, 200 lb man has a BMI of (200*705/72^2) = 27.2
(clinically overweight)

clinical observations are irrelevant, and BMI would force a table to be onhand.

Originally Posted by thastygliax

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.

thanks, I'll use this formula.

[Ze'Manel Cunha]

Originally Posted by Gadrin

clinical observations are irrelevant, and BMI would force a table to be onhand.

*shrug*
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 pseudo-realism isn't a big issue.

[Bathawk]

Originally Posted by thastygliax

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.

er how do I input that into my comps calculator? (particuarly "cubing" a number)

[whswhs]

Originally Posted by Bathawk

er how do I input that into my comps calculator? (particuarly "cubing" a number)

Is it a scientific calculator, or does it just add, subtract, multiply, and divide? And do you have Excel or another spreadsheet as an option?

[Brandy]

Originally Posted by Bathawk

er how do I input that into my comps calculator? (particuarly "cubing" a number)

With any calculator, cubing is just repeated multiplication.

(7/6)^3, if you don't have an explicit raise-to-power feature for some reason, is just (7/6)*(7/6)*(7/6).

Holy thread necromancy, Batman!

[Fred Brackin]

Originally Posted by Bathawk

er how do I input that into my comps calculator? (particuarly "cubing" a number)

For what I find to ne the simplest (but not necesarily most direct) calculations find the percentage of increase and cube that.

For example going from 6 to 7 ft is a 1,16 percent increase in height. so 1.16 x 1.16 x 1.16 equals 1.56 percent increase in weight. That would take you from 200 lbs to 312 lbs.