You will find everywhere discussions of ease in clothes design. Basically, if you want to be able to move in your clothes, or layer them, you need to add certain basic dimensions to your own. Beyond that, there is design ease, which is added (or not) in order for things to look good in a fashionable way :-). But alas ease is an art, not totally a science, and nothing makes a garment look bad like calculating the ease wrong.

Proportional ease

At first glance ease would seem to be a straightforward concept. Any patternmaking or design textbook comes with tables that tell you in a very scientific-looking way what to add to what body part in order to have the whole thing work. That is, you don't add as much to your biceps as to your butt, which makes sense. Best of all, they generally agree with each other, you won't find any book in print varying from the usual 3-4" of basic butt room. So why is it that many of us get clothes that look horrifyingly off by these guidelines? We spend weeks to years slaving away on a sweater, having carefully checked our gauge, and end up swimming in a potato bag, or at the other end of the scale poured into a sausage casing.

The reason is something that's almost never mentioned in these books: these numbers apply to what's considered 'average', in the US a size 10 set in the 40s. Let's not get into a deep discussion of why this is still the case in design circles while the real average US woman has demonstrably grown to a size 14, or why the models that show these supposed average clothes are on the whole 30lb less than they were half a century ago, well below any reasonable vision of health. The fact is that not only fat women are oppressed by these idiocies, talk to any normal tiny little bird-boned Vietnamese woman for example and they'll tell you that they too have an awful time buying grown-up clothes, and have to adjust their patterns to the point of complete redrafting. So most of the population is in this boat by now, very few of us are average.

These design tables for ease are actually gross over-simplifications. They're a condescending gesture toward generalized innumeracy - they assume you'd have a hard time calculating a simple percentage, and feed you the hard numbers as they would be for the mythical average. But they really should be a table of percentages, and you should calculate each value for your own measurements! It only makes sense if you think about it that a little person would need less fabric to be able to sit down than a large one, and that we all should get ease according to the size of what we're trying to sit on.

The real guideline should be that a classic fit has about 7-10% of ease for the measurement in question. That percent can vary from -10% for a really body-hugging fit to +20% for a really loose item. Now obviously you can just figure out what sort of fit you want, and then use that percentage of your own measurements. Or alternatively you can look at a certain recommended amount of ease for a specific design, calculate what proportion that would be for the average, ie what percentage of the standard measurement for a size 10, and then adjust the ease for your size using the same percentage, thereby getting the same design effect.

 3 inch ease7% ease
small too loose for small not much for small
medium just right for medium enough for medium
large too tight for large plenty for large

There are rough approximations you can use that will allow you to eyeball what you should be using in any context. For instance, I know I'm about 50% larger than a size 10, and my friend Priscilla is about twice as much, while her niece Trinh is on the other side of the scale, at about 2/3 of the same size 10. So if I were say making a surprise present, considering recommended classic butt ease of 3-4", I'd make sure that Trinh gets roughly 2-3", I get 6-8", and Priscilla gets 12-16". If I wanted to make a loose-fitting Miyake design, which uses about 12" of ease for a size 10, I'd give Trinh 8-10", myself 18", and Priscilla a generous 24". And we'd all get our very own measurements for a skin-tight camisole :-). It sounds simplistic, but it works for me.

Ah, and if you do run into math nightmares trying to figure all this out to minute fractions of an inch, just try using the metric system...

Fabric thickness

Another important factor in determining ease needed is fabric thickness. We measure a piece of fabric (knit or otherwise) on the flat. If that fabric is reasonably thin, we get a good enough mathematical approximation of a plane, and when we fold it up and sew it we get a circle with a diameter very close to the flat measurement of the piece.

But if the fabric is thick, as often happens in sweaters, we run into problems. Because the flat piece is the size what we want, we have to seam so the outside is the right dimension, and the extra thickness gets all bunched up inside the sweater. Suddenly that same outside dimension has to encompass not only our selves and our needed ease, but also what can be a considerably bulky amount of extra fiber. Boom! We're a sausage again.

So you need to adjust the percentage of ease that you're using from the preceeding section to reflect the heaviness of your fabric. Say you want the very same look of classic fit. Sewing a normal cotton blouse? Use 7%. Knitting a bulky sweater? Go for the full 10%. You need to adjust for fabric thickness independently of what proportion you want for design ease, usually within a range of 3-5%.

regular ease
outside is size
thickness ease added
inside is size
thickness makes it too tight thickness is out, ease is good

Another way to think of this: ease is the difference between your body and the inside of the garment. Say you know what you want the inside to be, and the fabric is nearly 1/2" thick (1cm), common for sweats, fleeces, winter coats, sweaters... Since circumference is equal to 2*pi*radius, if you add 1cm to the radius, you're adding more than 6cm to the outside circumference, or roughly 2 ½ inches. That could be almost double your ease if you're small, but even a very large person would feel the loss of 2 inches of ease. So it's hard to measure the thickness of a swatch, especially if it's very fuzzy, but think of it roughly in terms of allowing at least 6 times the thickness of the fabric as extra ease.


In addition to all this, you should probably give a thought to drapeability of your fabric. Something that drapes well can be made looser than the very same thickness of fabric that doesn't without making a big design statement. Think crisp 50s fabrics in fitted styles, versus loose flowing drapes of the 80s.

And don't confuse drapeability with the thickness we were discussing above. A plush alpaca knit drapes much better than a thin crisp silk. Although as a general rule thicker fabrics drape less well, some fibers drape better than others (alpaca better than merino for instance), and loose weaves drape better than tighter ones. Drapeability is the result of a complex interplay of all these factors. The only real way to know is to look at what you have. Put a largeish piece of fabric over a round object, like your bust or a fist - does it hug the object and puddle around it, or does it merely skim over the top? This is the best argument for making a large gauge swatch in knitting, so you can evaluate the drape of your fabric properly.

In any case, you might tend toward the lesser amount of ease in designing with a stiff or crisp fabric, and toward the larger with a drapey one. But keep in mind that firm fabrics are less forgiving of ease mistakes on the smaller side than stretchy ones, obviously you aren't as likely to be popping seams in knit skirts :-).

Confused yet? Do keep practicing, and thinking about all this... your clothes will be all the better for it in the long term.

First published: 01/10/03

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