The Big Jimmy Jab knitalong is kicking off in just over a week, so I thought I’d share some handy tips on how to pick a size. For the Big Jimmy Jab is not, you see, like other circular yoked jumpers. (I’m trying and failing to resist the urge to say “it’s a cool jumper” here, because many, many jumpers are cool. But MEAN GIRLS REFERENCE. Got to be done.)

You see, I’ve always had a bit of an issue with circular yoked jumpers. Not such a big one that I’ve stopped knitting them, or a big enough one for me to attempt to start a campaign against them. But they’ve always just…got on my tits.

Specifically, they’ve got on my tits wrong.

Why don’t boobs and circular yokes get along?

There’s a simple problem with a circular yoked jumper; they’re the exact same width on the front and back. That may be fine for some, but if like me you are “blessed” (I use the quotation marks because of back pain) with what is referred to in polite company as a “full bust”, then you might find this fact a bit troublesome.

Because you choose the size to knit based on your full bust circumference, plus the intended ease, you often end up having to pick a size that will fit your boobs but not the rest of your body. It can make for a jumper that totally swamps you, which is…well, annoying. A bit of waist shaping might take it in and do away with some of the “boob tent” effect, but it’s never going to be a properly good fit.

And how does the Big Jimmy Jab jumper fit boobs better?

In short; because I’ve stolen a concept that has long been used in sewing and have decided to apply it to knitting. The bust adjustment.

The basic principle is simple: you knit a sweater that fits the rest of your body, and then make extra space for your boobs. It solves all your annoying fit problems in one; the shoulders are the right size. The upper back doesn’t gape. The sweater doesn’t make you look several months pregnant.

So how do I pick a size for the Big Jimmy Jab?

The simplest way to explain it is to give you a look at the size chart. Because while you’re often told to pick a size based on your bust measurement, things are a little different for the old Big Jimmy Jab.

See that second column there, “actual upper bust”? That’s the key measurement for the Big Jimmy Jab. You want to be measuring that on yourself (here’s a handy tutorial on how to do that), and then picking the size that’s closest to that. Obviously, the normal rules of fit apply here; if you’re between sizes and want a looser fit, then go for the bigger size. If you’re looking for something a bit more fitted, then go down.

Once you’ve got your upper bust measurement and picked a size, you need to decide whether to work the bust adjustment. I’ve put two measurements in for the finished chest circumference of the jumper – with, and without the bust adjustment. Think about whether you want/need the additional space that the bust adjustment gives you, and then you’re golden.

But what about wearing ease?

Well, that’s all factored into the sizing table; the jumper is designed to have 4-6in (10-15cm) of positive ease, so that it’s got a loose, comfy fit to it. That means the finished chest measurements for the jumper are that 4-6in (10-15cm) bigger than the actual chest measurement of the body they’re intended to fit.

So, let’s take me as an example. I have an upper bust measurement of ~39in, and a full bust measurement of 46-47in. So I’ve knitted myself both a size 5 without a bust adjustment to get a boxy, cropped sweater, and a size 4 with a bust adjustment to get a slightly more “classic” fit.

And when it comes to my jumper for the knitalong, I’m going completely rogue and knitting myself a size 3 with bust adjustment, for a close-fitting jumper that for once will be relatively close-fitting all over.

The lesson here? You can make pretty much whatever fit you want, but for once your boobs will have been factored into the equation. Nice, hey?

If you want to know more about adjusting jumper patterns to fit your boobs, I run an online workshop all about it.