Have you ever seen a pattern where every single size on the tissue paper has a bigger and bigger neckline? Or noticed how a shirt in a store has an incredibly long sleeve and an extremely wide shoulder, for no apparent reason?
Those, my friends, are common mistakes made in the world of grading from straight to plus size, and from straight to petite and tall. Necklines don’t need to increase for every single size. They also don’t need to decrease for every single size. Think about it: our skeleton isn’t actually growing for every single size in a range, only our body mass.
Any circumference growth that grading needs to account for is muscle and fat mass, and this grows on the body outwards and in curves. And that means that while you do have to account for some length increases (you will always need some length as well as width to adequately cover a curve), you don’t need the full grading amount (both ways) for every single measurement.
The only areas where we need to worry about skeletons growing are childrenswear and juniors. Otherwise, skeletons stop growing completely around 18-20 years old. Therefore, it doesn’t make sense to grade as if they keep getting bigger.
True body length grading is another story — there are standard rules based on heights and size ranges, and each measurement may need to be adjusted based on styling. (An empire seam placement versus a peplum seam placement, for example, or a body length for a size 12 versus a size 26).
This is why, if you are purchasing cheap apparel in plus sizes, the sleeves will usually be too long. The company has probably kept a standard grade at the shoulder width, as well as the sleeve length. For example: the average height of an American woman is only 5’4″; this is borderline petite by RTW height standards! Even for a size 22, the sleeve length does not need to increase the full grade amount if the entire grade is based on a size 8/10, and keeps the full shoulder width grade. You’ll also see on collared shirts that the necklines can be huge: the collar stand itself will stand away from the neck at least 1/2″ on each side. As a person increases, the neck may grow mass at the front under the chin, but I’d wager that for most women, the neck and shoulder widths don’t get as big as “standard grading” thinks they do. I’ve seen this neckline issue even on some better/bridge women’s labels, and can only assume it’s because the company won’t spring for size set* fittings.
*A size set fitting is where you arrange for a model in every size you carry (with a body shape that’s similar to your main fit model — apple, pear, etc.) to try on a specific style in each size, and evaluate the grade from smallest size to largest, all at the same time in the same room. They’re extremely helpful for issues like these. The best kind of size set fitting is when you get to try your styles on different body shapes, to get an idea of what kind of challenges you might have in a larger market share.
It is, of course, appropriate to grade for total body proportion on a style. However, many people don’t bother to see what that might look like, and simply rely on a standard grade rule.
Petite and Tall sizes are very poorly served in RTW: offerings are usually online-only and the selection is limited, especially for Petite Plus and Tall Plus. Home sewing pattern companies don’t usually account for these extended size ranges either, with a few exceptions. To help with this, I’ve created a spreadsheet for all you lovely sewists out there!
This sheet will help you figure out what kind of length adjustments you might want to make to a pattern before you cut your first muslin. You’ll pop in the pattern measurements of the size you’d usually make in the “Pattern Measurements” column, and then the spreadsheet will feed you suggested revised measurements! This includes inseams, sleeve lengths, and even rise lengths.
There are two tabs in the sheet — one each for tops and bottoms — and both inches and centimetres are served in the spreadsheet (if not in my numbers below). Keep in mind that these numbers are just suggestions for a starting point: you may need to make further adjustments based on your figure. It’s written for womenswear, but can be easily adjusted for men’s.
In the apparel industry, these numeric changes are called “conversions,” but for our purposes “Jump Numbers” sounds much more inclusive. 🙂
Additionally, here are some generalized shortening/lengthening reference positions that may be helpful: straight size is based on a RTW Missy 8/10, and plus size is based on a RTW Missy Plus 18/20, both for someone between 5’6″-5’8″. Again, you may find that these need to be adjusted for your particular pattern depending on the height the pattern was drafted for, but this should at least give you a good starting point to work from.
Straight size bust apex placement: 10 1/2 to 11″ below High Point Shoulder
Plus size bust apex placement: 11 1/2 to 12″ below High Point Shoulder
Straight size waist placement: 16″ below High Point Shoulder
Plus size waist placement: 17 to 17 1/2″ below High Point Shoulder
Straight size low hip placement: 24″ below High Point Shoulder
Plus size how hip placement: 26 to 26 1/2″ below High Point Shoulder
Bicep placement: 1″ below armhole
Elbow placement: 9″ below armhole
Thigh placement: 1″ below crotch (Leg placements may change based on how low the crotch fits on your particular style)
Mid-thigh placement: 6″ below crotch
Knee placement: 12 1/2 to 13″ below crotch
Calf placement: 18 1/2 to 19″ below crotch
Please note: if you are going from straight size to plus size, I would add an average of 2″ in the front body length to start. The front body length will be longer than the back body length; this will change based on you, but I would imagine a back length would be at least 3/4 to 1″ shorter than the front, based on standard sway-back adjustments. Otherwise, feel free to use the spreadsheets for any other lengthening / shortening needs you may have.
Another note: when you are making these adjustments for the tall jump ranges, you will want to maintain your circumference shaping. As an example: if you are increasing your rise length, add the same amount all the way across the waist to the outseam so that both rise and the outseam will increase by whatever amount you chose, and the waist shaping line and waist measurements will stay the same as the pattern. If you lengthen a sleeve, keep the sleeve opening as the pattern–just extend the length and re-blend the forearm shape. (Unless, of course, the sleeve opening is too wide). Petites may find that you would like to reduce your body circumferences as well. I’ll leave that up to your personal preference, since that will change based on your numeric size.
What questions about length adjustments and grading do you have? As always, and as an almost-shorter-than-average-person, I’m happy to help!
Gabby is a technical fashion designer, fit specialist, and prolific googler. She lives in Denver, raises tiny littles, reads, embroiders, makes, experiments, fails, learns, tries again. See her on instagram @ladygrift.