September 2017: Re-Posting this because today I just read a simple comment in a FB group that explained so well, why patterns are sometimes graded so “jumpy”. The question was “Can someone teach me about proper pattern grading. I hear some people saying that sizes need to be graded even amounts through the sizes.”
And the best answer ever came from Sandra Bryans , owner of Sewanista Fashion Workshops in Western Australia and previously a professional pattern grader at a childrens-wear firm. She explained “There’s a difference between a raw measurements chart and a grading chart. Sometimes there are uneven jumps because that’s how the data panned out, but for grading it’s much better to be consistent.”
This is what I’d been trying to explain: the raw data is the body measurements chart, which can have jumps between sizes. If the pattern grader follows each size measurement too literally, you can end up with a jumpy pattern. It’s far better, for the purposes of sewing or shopping, to have a smooth, consistent grade between sizes. As Sandra says “If the grading is consistent then the parent can buy the next size when the child needs it rather than according to a hypothetical growth chart.” The same is true of adult apparel: if we change sizes, it’s helpful when sewing or shopping to have consistency between sizes so that each size up is larger by a consistent amount.
Thanks so much, Sandra!
This is the original post (February 2017):
Have you ever used a pattern that “jumps up and down” in the grading between sizes? Recently I was trying a pattern that had grades jumping between 1/4″, then 1/8″, then 3/8″:
Since I come from an industrial background where this would never happen, it makes me wonder not only why this is, but how did it happen? Grading is a simple matter of sliding the master pattern up-and-over by a consistent measurement “rule”, so why are there inconsistencies? After all, garment industry patterns have consistent grading, Big Four paper patterns have consistent grading…..the grade may be smaller within the smaller section of sizes, and larger within the larger sizes, but never jumping up and down. Why does this happen so often in indie pdf patterns? I have a theory…..
First of all, why this is even important? If patterns are made for the home-sewist who is making a single garment, not making a size-range to sell, it is less critical that the grading be accurate than it would be for mass-production. I’ve read many a FB post where home-sewists say they could not care less if a pattern is graded correctly because they are only making one outfit for one person, and I understand that…especially if it’s for a person who has finished growing, and doesn’t gain or lose weight.
But if you sew for a growing child, or for siblings (and you want their clothes to be proportionate) it does matter. And for those of us who sew to sell, having consistency in the full size range is important.
….or using a $20,000 Gerber machine/AccuMark® or Optitex CAD software professional system, the theory is the same: from a fit-approved pattern in a middle size, the pattern is shifted up-and-over on the X and Y axis according to the established grade rule to create the next size larger …or down-and-over to make the next size smaller. The shape remains the same, the angles remain the same, the only thing that changes is the size.
But now many indie designers draft patterns directly on a computer screen using generic software such as Illustrator:
Instead of sliding a master pattern, the designer can plot measurement points on the screen directly from the size chart. Unfortunately, the further away the designer gets from the basics of drafting with a French curve and hip curve, the greater the possibility that the resulting product can be inconsistent in shapes and angles (which I’ve discussed many times). But what about the inconsistencies of measurements (not shapes) in grading ? Where is that coming from?
I have an idea: there may be a possibility that some grading is done with the size chart taking priority over the grade rule.
Grading patterns is a process aimed at fitting the largest variety of people adequately. It is the opposite of couture, which aims to fit one person perfectly. Commercial pattern grading involves compromise; it doesn’t let perfection (for one person) dominate over the good (of the most people):
If pattern grading aims to fit the widest variety of customers, this involves compromise, including the connection between the Size Chart and the pattern grade. For example, look at this portion of the above graded pattern piece, just sizes 1/2 to toddler 4:
Here is the BODY SIZE chart info for those sizes (in descending sizes to match the pattern piece shown above), and the corresponding grades between sizes, and then the coordinating quarter-grades (total chest circumference divided by left/right/front/back):
That shows how the pattern grade jumps around from 1/4″ to 1/8″ to 3/8″ to 1/4″. The graded pattern does correspond to the size chart, and the size chart itself is fine: kids often do grow more from size 1 to 2, than they do between 2 and 3.
However by following the size chart so literally, there’s no garment to fit the child whose size is halfway between size 1 and 2. The pattern doesn’t fit the largest number of customer adequately. The perfect has become the enemy of the good.
An apparel production company would smooth the grades evenly, with a 1/4″ grade for every size:
Now this part may be confusing but here goes: a garment manufacturer might keep the original standard SIZE CHART as before, and STILL grade this style evenly between all sizes:
Does this mean that the size 2 garments are going to slightly tight, comparing garment to size chart? Yes. This is a compromise made to reach the goal of fitting the most number of customers, with a consistent grade between sizes.
The bottom line is this: if a pattern designer is marketing to home sewists who are going to make single garments, then having a smooth grade between sizes may not matter. It would be nice to know, however, which patterns are suitable for home-sewing only…and which can be used to create a smoothly graded set of garments for selling.
Postscript 2/20: I received a question about why a size chart (especially for such small sizes) have a 1 and 1/2″ grade between sizes. Two reasons:
Children may grow quite a bit between sizes 1 and 2, and many patterns have an in-between size (18 months), but in a loose-fitting garment like this, possibly the designer decided to skip the 18 month size.
Size charts are often rounded to the nearest half-inch, for the consumer’s sake (it’s difficult for some people to measure a body to the quarter-inch). So while the designer’s “in-house” size chart (for manufacturing) might have a consistent 1 and 1/4″ grade between sizes, the compromise is to make one of the grades 1″ and the next one 1 and 1/2″ on the published size chart (for the manufacturer’s website, or on hang-tags).
The goal: a consistently graded rack of apparel that makes shopping as easy as possible:
Update 9/24/01: I received the following reader comment: “But this supposition of “jumpy ” grading cant be applied to the designer of the above sizing chart as further analysis of their patterns has not been completed.” So I printed out Lauren, Rose, Brooklyn, Sophie, and Evie. They all have the same size chart, and the same jumpy grading.