Standard Disclaimer: When I write a post like this, I think about the numbers and proportion. I would be heartbroken and shocked if my words were taken as a value judgement of some kind. I’m just playing with numbers here, seeing what turns up. I don’t care what size someone is, I just want to dress both the body and the person inside the body well.
When I set up the form for the Waist to Hip Survey, I set a goal of 300 entries and thought myself very ambitious and figured I might hit that number in a few weeks or a month. By Thursday, we had surpassed 300 and I realized I better start digging around in the numbers to see what turned up. I’m leaving the page open and in the sidebar for now because I have an even more ambitious number of sets I’d like us to reach: 1000.
I’ve been curious for quite some time about the relationship between waist and hip measurements and the resulting ratios, and how that might apply to pattern sizing and drafting. I do like to work through little puzzles like this to find my own answers when possible.
You can find the ratio by dividing the waist measurement by the hip. If you’re mathematically minded: ratio=waist/hip. The bigger the difference between the waist and the hip measurements, the lower the resulting ratio number.
The basic idea I wanted to test on real measurements is this: As waist size increases, the waist-to-hip ratio decreases. That’s pretty basic, but I wanted to check it. I also had a few secondary questions:
- .7 is considered the “ideal” ratio for waist-to-hip measurements, but what is the commonest ratio?
- How much does the waist to hip ratio decrease as size increases?
- Can I find body shape types from only these numbers?
- What ratios do some common pattern companies use?
I’ll show you what I found, question by question.
First I’ll run through the limitations of my survey. All numbers presented come from a sample size of 359. I am still greedily accepting measurements for the survey, but for the sake of this post I stopped on Friday morning at 359.
Secondly, all measurements are self-reported, which means there may be some variation on measuring tape tightness and whatnot.
Thirdly, the data set is limited to people who sew. I assume. I write a sewing blog and posted about this survey in sewing channels. It would be interesting to explore how sewists’ measurements relate to the rest of the population, but for now we’ll leave that.
And finally, I work in both cms and inches. I use cms in my spreadsheets because the decimal points make more sense than a fraction in that form. Let me know when I forget to write both.
As waist size increases, ratio decreases
This is true, and it’s common sense. A few months ago, I wrote about elements of good fit. One element of good fit involves fat/muscle distribution on the body. Another element involves bone structure.
A waist measurement is a “fat/muscle distribution” measurement. You don’t have waist bones. Waist measurements also depend on the way your guts are put together and the hormonal cocktail flowing through your veins, but that’s not within the realm of fitting clothing so I don’t know much about it.
A hip measurement may be a mixture of the two types. Someone with relatively low body fat may have a wide pelvis. Another person with a relatively small pelvis may be carrying greater mass in the hip area. To compound the hip problem, mass may be distributed more toward the back, toward the sides or distributed evenly around the hips. This makes the hip measurement somewhat “less reliable” from my point of view (too many variables), though when I pick a pants pattern I use my hip measurement to choose the size.
This shows the breakdown of the waist measurements I received. X=”waist measurements” so the commonest category is those measurements that are greater than 70cm but less than 80cm. That is, the commonest category is “greater than 28″ but less than 32″”.
And here are the hip measurements. In this category, “greater than 100cm and less than 110cm” was the largest category. To put it another way, the commonest range lie at “greater than 40″ but less than 44″” through the hips.
I separated the measurements into “60′s, 70′s, etc” and found the average ratios associated with each waist measurement. As expected, the ratio decreases as waist size increases. This is broad, but it shows the observation was correct. Ratio does indeed decrease as waist size increases. In inches- 24″, 28″, 32″, 36″, 40″ through the waist.
What is the commonest ratio?
By the numbers I have, the commonest ratio is greater than .75 and less than .8. Combined, the commonest ratio is greater than .7 and less than .8. Again, that’s pretty broad.
What do you think? I have some other questions to explore, but when I tried to put everything into one post it became very long reading indeed. Tomorrow I’ll look at my other questions: Can I predict the rate of ratio change from one waist measurement to the other?
What do you think so far? Would you like for me to ask the numbers some questions? Please, clever people, pick some holes. Also, I made a chart of ratios a few pattern companies use- which company would you like to see?
Tune in tomorrow for part 2 of the numbers breakdown and my idea for a shapes survey… And then it’s time to focus on this month’s hack! I’m inspired by collar shapes from the early 50′s and Tanit-Isis’ unwitting challenge to use polar fleece. I can’t stop thinking about working with it now she’s put it in my head, it should be very interesting!