Imagine you are a pattern maker. You have a great design all worked out. But what sizes should you include in your pattern?
You might start by looking at what other pattern makers are doing. Then you might look at what standard size ranges are being used by ready-to-wear clothing manufacturers and large commercial pattern makers. But a small pattern maker can’t always afford to make every pattern in every size, so how do you choose?
A Look at the Numbers
The body weight of adult women follows what is called a standard distribution. If you charted out the number of people by their body weight, it would make a curve. There would be a lot of people in the middle of the curve (around the average weight), but not many people out at the ends of the curve (with very low or high weights).
According to SizeUSA, as of 2004, the average bust size in the US was 40″. That translates to roughly a size EUR 44, or US pattern size 18. That’s the centre of the curve.
Indie Pattern Makers
What many independent pattern companies choose to do, is offer their patterns in sizes 6 to 18 (or average). If you chart that out, you can examine what is called “the area under the curve” and use this to calculate the percentage of the population in that range.
For independent pattern companies that offer their patterns in sizes 6 to 18 (the green area under the curve), that area is about 43% of the total population. That means that if you make a pattern available in that size range, only 43% of the general population can use your patterns.
That’s not a huge number, so you might think about extending your range of sizes. But in what direction? If you look at the chart you can see that by extending the range down, say two sizes, you make the area under the curve just a little larger, but if you extend the range up by the same number of sizes, you make that area much larger. In other words, you can find more buyers by adding sizes nearest the centre of the curve (size 18), then at the ends.
Big 4 Pattern Makers
That’s what commercial pattern companies do for their regular pattern range. Often, they offer patterns in sizes 6 to 22. With that range, about 63% of the population can use their regular patterns. They’ve just increased their population of potential buyers by about half. But instead of 7 sizes their range includes 9 sizes.
An Ideal Limited Pattern Range
When you produce a pattern, there is an additional cost for producing and grading each size. Not every pattern maker can add extra sizes. So lets assume that as an independent pattern maker, you can only afford to draft seven sizes. Which should they be? In order to include the largest number of potential buyers, you should centre your seven sizes around the average size. If you include sizes 12 t0 24, 56% of the general population can use your patterns. In other words, by shifting the range of patterns you are providing up by a couple sizes, you can make more money at no extra cost.
Our average weight has been increasing over the past several decades. In the 1940s and 1950s, when standard clothing sizes were developed, the average bust measurement was 35″, about a size 12-14.
If you look at the Big4 pattern makers, this is the centre of their current range of sizes. Most likely, they originally organized their pattern size range to centre around the average size (in the 1940s and 1950s), in order to maximize profits. But since then, our bodies have grown out of that ideal range, and the Big 4 pattern companies have not adjusted.
If you look at the small range that many small independent pattern companies are using (6-18), they are also centring their size range around this outdated average, just like the Big4 pattern companies. But they don’t have the historical reason to do so.
A Sample Extended Pattern Range
And what would happen if you matched the size range on both sides of the average? What would happen if you offered sizes 6 to 18, but then also offered sizes 18 to 30? You’re patterns could be used by 86% of the population. You would double your population of potential buyers (and presumably your profits). Of course now you would also have to draft an extra 6 sizes. And of course, you can always extend that range even further.
And would that extra segment of the population buy your patterns? It’s hard to predict. But assuming the patterns were well drafted, and fashionable, you would be adding a population of potential buyers that are underserved by both large commercial and small independent pattern makers, but also by the ready-to-wear clothing industry.
Statistical Caveats
This model of pattern sizing is approximate and depends on a number of assumptions.
Human body weight follows an approximately normal distribution, so it’s logical to assume that clothing sizes do as well, but they might not. That data has been compiled by private companies, but it isn’t publicly available.
This model assumes that clothing sizes vary by equal amounts along the curve, that measurements like bust size and body weight are perfectly correlated, but that isn’t necessarily the case.
Nevertheless, it’s logical to assume that the model would be a good approximation of size distribution in the population and the calculations shown here would hold up.
So what sizes should you include in your pattern?
Based on time and budget constraints, determine how many sizes you can draft, test, and print. Then centre those sizes around the average, size 18 (EUR 44 or L with bust 40″), with an equal number of sizes above and below that point. (And yes, size large, is in fact average).
Of course, this takes into account only cold hard economics of choosing a size range. There are many reasons, besides profits, that would lead to different choices. In a perfect world, all patterns would come in all sizes – and they would all look amazing! (perfect world right?)
Your thoughts are welcome in the comments!
The Finished Garment 