The imperial system of measure has a reputation for being unwieldy and complicated -usually deservedly- in all respects save one, that of drafting for the human body. While I can’t prove it, I think that it was precisely due to the particular suitability of inches in drafting for human bodies that are what made the imperial system so prevalent. While the system isn’t infallible, it can be a great rule of thumb for troubleshooting. In the forum we’d been discussing whether one’s instructor was using a good method. Said instructor was not grading for length in the neckline but was adding 1/4 to the armhole length and then again, nothing from armsyce (armpit) to the waist so it was easy for graders to see, without having a pattern for comparison, that this wasn’t the best way to go about it.
Most adult human bodies can be broken into eight head heights. Off to the right is an illustration from the Art of Drawing the Human Body.
Using this sketch, it is apparent that for every 1″ in height increase (or decrease if that applies), the pattern is lengthened according to these fixed points. For example, a cropped waist length top would grow 1/8th from nape to armpit and another 1/8th to the waist -and in precisely these locations. It wouldn’t do to add the 1/4″ of total length to just one area but must be spread according to the breakdown of dimensions of human height. Another example is a pair of shorts. Shorts would grow a total of 1/4″ in length with half going from waist to hip and another 1/8th from hip to mid thigh. Obviously styles will vary but this is a simple way you can check a pattern grade for people who are height and weight proportionate in that the patterns should grow commensurate to these guidelines.
In other words, to check a grade, you can’t compare over all length of two sizes relative to each other. First you have to line up the shoulder at the neckline to see the rate of grow to just the arm pit. Then you’d reposition the pieces to match at the arm pit to check the percentage of grow of each to the waist.
Last are two caveats. The first is, this applies to adults; children are “morphing” as they mature. Here is an illustration from pg. 170 of my book (right). An infant’s body is broken into fourths meaning one head length is one quarter of their total body length. Their trunks are disproportionately long, about half their total height with total leg length being about the same length as their heads.
The second caveat is that this applies to people who are height and weight proportionate. As people get heavier, the distance from point to point cannot be determined by strict x-y cartesian coordinates with a length caliper but are more accurately triangulated, “growing” disproportionately to the standard discernible pattern. This applies regardless of height as it is dependent upon girth. Moreover, as people gain weight, parts of their bodies will become disproportionate to each other which is why grading for plus sizes is a challenge.
Anyway, I just thought you’d appreciate a down and dirty method of comparing length grades if you have any doubts about the results you’ve either rendered or hired out.
Off topic:
I collect archaic mensuration depictions among other weird things. I don’t think I’ll ever have cause to publish this illustration below in another context but I think it’s fun. It’s from an ancient Egyptian text and even subtracting the overly elaborate headdress from total divisible height, doesn’t break down according to any scale we use today except perhaps one. It roughly approximates the scale of centimeters as expressed in terms of inches. I’m probably not saying that right (1″ =2.54cm) but I’ll have my math guy correct my oversight this evening.
Said instructor was not grading for length in the neckline but was adding 1/4 to the armhole length and then again, nothing from armsyce (armpit) to the waist so it was easy for graders to see, without having a pattern for comparison, that this wasn’t the best way to go about it.
It amazes me that anyone does this. How can you not tell that different heights have a different length between armpit and waist? I’ve known that since I began drafting, adjusting for height/proportion was one of the first things I was taught (I was assisting a custom bridal designer and seamstress, so perhaps that would be why the emphasis was so much on this factor).
I, novice-at-grading that I am, sort of instinctively know this; seems common sense to me. I have only just recently begun to study grading (thanks to all the posts here with good info too), but, have done custom clothing. Like Maura, when you are making clothing for a variety of heights and sizes this is just something you learn.
Certainly this instructor should know better. Maybe the instructor needs a refresher course, or a continuing education class or two.
I’m always amazed at how you often seem to write a post that’s exactly relevant to one of my current projects. I’m testing as many of my drafting methods as I can (I collect them) as preparation for a class I’ll be teaching soon. One of the texts is a method developed in the 1970’s for use in the New South Wales technical training system. (It was, I suspect, an in-house textbook, and so I’ve never seen another copy, or even heard of it before.) At the time, this was acknowledged as the best in Australia. It uses 1/4 height for the nape to waist, as you’ve said, and that does generally work. (I really like this book, it explains proportions so simply) Then FW Morris, available at vintagesewing.net, gives a formula for how much is added when the flesh size is disproportionate to frame size. From memory, it’s 1/8th inch per 2 inches of bust size over 34″. Most other methods give a set of standard measurements, with no explanation of why they are anything other than the results of averaging lots of direct measures into a table. The more drafts I test, the more I appreciate the proportionate systems over the direct measurement methods.
I agree completely about using imperial for body measurements. Even born and bred with the metric system, I prefer to measure in inches. The inch, I understand, was based on the length of the last thumb joint, so it makes sense that it relates to the human body. Wasn’t the metre more or less an arbitrary length originally?
I read once that the foot is a standardization of the biblical cubit. A cubit was the measurement from the wrist bone to the elbow, which is also equal to your foot. I don’t have anything to cite, but perhaps you can find something. That would also make sense about the inch being the thumb joint.
I really enjoyed this post, even though I have no knowledge of grading. That thing I find interesting about it is that I DO NOT FIND that many of the clothing I try on is grading appropriately! Pants are longer, but sit too low on the hips, so they fit incorrectly; short sleeved blouses fit everywhere besides the shoulders & chest; and tank tops can be too short.
Maybe it’s just me though!