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One of the biggest challenges when preparing to knit a garment is choosing which size to make. It’s complicated, because not all patterns provide information the same way, in the same format—and because the right answer is also a matter of preference!

A few tips on how to get it right.

Measure yourself. For sweaters, vests, and cardigans, measure the circumference around your torso under your arms; if you have a generous bustline, also measure around the full circumference of your bust.

Measure a similar garment. It doesn’t even have to be a sweater, it might be a t-shirt or a jacket. What’s important is choosing a garment with a similar structure and weight of fabric.

Check the pattern to see if there’s a fit recommendation.

Sometimes it’s phrased casually: “Choose a size close to your body measurement.” Sometimes it’s phrased more formally in terms of ease: “The model is wearing the sweater with 8″ of ease.”

Let’s look at the sizes for the Crowberry Sweater in Field Guide No. 26: Moss.

For each size, there’s a range of bust measurements. You’ll choose your size based on your bust measurement.

How big should the garment be, compared to your body? The term for this is ease.

What’s Ease?

There’s a formula: ease equals garment circumference minus body circumference.

If you’re wearing a garment with positive ease, the garment is bigger than you. Your winter coat fits this way.

If you’re wearing a garment with negative ease, the garment is smaller than you and stretches to fit. Tights, leggings, women’s swimwear, and underwear fit this way.

If you’re wearing a garment with zero ease, the garment is the same size as you. Think of a camisole that is designed to fit under another top.

A garment on its own doesn’t have any ease. Ease is about the relationship between the body and the garment that’s on it. Think about taking your favorite cardigan to your next family reunion. A load of people of different ages and body shapes and sizes could wear it, but it will fit differently based on the size of the person wearing it.

The schematic tells you what the measurements are when the garment is done.

For Field Guide patterns, choose the size based on your underarm circumference: for example, if you fit into the first listed range, make the first size; if you fit into the sixth range, make the sixth size.

For patterns that provide a suggested amount of ease, choose the size based on your underarm circumference plus that suggested amount of ease. For example: If your body measures 46″ around under the arms, and the pattern suggests 4-6″ of positive ease, look for a size with a finished torso circumference of about 50-52.”

If you have a generous bustline, compare the finished measurements of the suggested size to the circumference of your body at the fullest part of your bust. You want to make sure that the garment at that point is the same measurement at this point, or a bit larger.

You actually don’t need a lot of clearance around your full bust—if the garment is too big around the fullest part of your bust it will tend to look sloppy or droopy. Choosing the size based on your underarm circumference gets a better fit in your shoulders and neckline.

If the recommended size doesn’t clear your full bust circumference, there are three possible solutions.

  • Consider going one size up.
  • Add bust shaping or darts.
  • Find another garment with a shape that works better with your body shape.

There is a little bit of play in these numbers. If you want the garment to fit slightly bigger or smaller than recommended, or if you don’t fit the range, then you can absolutely go one size bigger or smaller. To get a sense of how it will work, compare the measurements of the size to your own body, and to garments you already own.

Note that different garments are designed to be worn different ways. Just as you wouldn’t want your winter coat to be skin tight and you wouldn’t want a swimsuit to be baggy, you need to stay fairly close to the recommended fit.

It’s worth spending a few minutes with a tape measure and reviewing the pattern’s size information before you cast on to make sure that the garment turns out exactly the way you want! After all, knitting a sweater is a big investment of time and love, and you want to make sure it fits you well.

About The Author

Kate Atherley is a teacher, designer, author and technical editor. She’s also the publisher of Digits & Threads, a magazine all about Canadian fibre and textile arts.


  • It took me a long time to realise that one needs to think about hips as well. If the garment is straight down and your hips are bigger than your bust or underarm measurement you will want to add some a line shaping if you want the amount of ease to be consistent all the way down the garment.

    • I have to fit my hips, as well! For the Crowberry vest I just completed, there was no pattern at the bottom. So I cast on enough stitches to fit my hips (mine was longer than pattern), and decreased my way up and had the right amount of stitches for the pattern when I got to the top. For top down sweaters, I make the size to fit my top portions, and increase on the side seams going down. I put sweaters on a string and try them on a lot to get this right. Lots of math to get the right ease and of course ripping when it’s not right…but they fit better now.

    • This is part of why I haven’t made a sweater for myself, only for my kids when they were little. My hips are larger enough to need the additional shaping. The other reason is because I wear XL in store bought clothing, but in many patterns my measurements are 2XL or even 3 XL. So it would be a big investment of yarn and time.

  • Oh mercy! I thought when it said designed with “x” amount of positive ease, that if I picked the range I fit in, the ease was built in to that size. Explains a lot of not quite fitting like I thought. Sheesh.

    • It’s complicated, as Kay says, because (annoyingly!) not all patterns express it the same way, and we see numbers for both “size” and “finished” or “actual” measurements. “Finished” or “actual” measurements (and those listed on the schematic), are the measurements of the *garment*. If there’s a corresponding body measurement/size listed, then that’s suggesting the size of the body that might wear that particular garment of that measurement. And the difference between those gives you a sense of how much ease the garment is designed to be worn with.

    • @Nancy; I believe that IS what that means; “designed with “x” amount of ease” does mean you supposedly don’t have to calculate ease when you pick your size, its already calculated in. Someone please correct me if I’m wrong!

      • You’re correct. But as pattern writing can differ in our non-standardized knitting world, I always compare the size to the finished measurements of the garment, that shows definitively how much ease is built in. If it’s a 40 inch bust size, and the finished measurement of the bust is 44, the finished sweater has 4 inches of positive ease.

  • This is the best explanation I’ve ever seen! Thanks.

  • I like positive ease in most of my sweaters, but I just learned that I’ve been doing the measurements all wrong! Thank you for this article! My next sweater will fit better!

  • No wonder my daughter’s new sweater is huge! I did the measure-around-the-largest-part-of-the-bust thing and then added the recommended ease. Yikes! Thanks for this very thorough explanation.

  • Oh My! I think you have answered my issues with getting the right fit! Thanks so much!

  • Schematics are essential! If it isn’t clear whether ease is built-in or whether to use my high bust or full bust measurement, a good schematic tells me everything I need to know, especially which areas I might need to tweak (hem, upper arms, bust, etc). After a few sweater disasters, I no longer knit any garment pattern without a schematic. I know I can find the various stitch counts and figure out the measurements for myself, but the lack of schematic is often a sign of other problems and usually not worth the risk.

    • It would be nice if designers would note on their pattern description “schematic included” !

  • Kate –

    As always, your posts are very clear, informative and helpful. Thank you. I appreciate what you do.

  • Great lesson. Thank you.

  • This was written so clearly, thank you Kate!
    I completely agree about the importance of a schematic in the pattern instructions, so helpful. And many of the knitting “gurus” state this in their classes too, Patty Lyons, Kim McBrien Evans, Franklin Habit for ex.

  • I found that a good well-fitting bra makes a big difference in fit and comfort. Worth investing in one! (Especially considering the time and resources involved in knitting a sweater.)
    The description of ‘ease’ in this article are priceless by the way! Thanks! Will save forever!

  • So what exactly does it mean when the pattern reads lets say 42 bust with positive ease? The ease is included in the size or not?

    • You can also do the math based on the gauge. Take the total number of stitches at the spot in the pattern that is after the sleeve divide for top down or before for bottom up. It should be written in the pattern at that point. Then divide the total by the gauge per INCH to get how many inches at that point.

    • You can know this by comparing the finished measurements (on the schematic or written out in the pattern) to the size. If the size 42 bust shows that the finished garment has 44 inches at the bust, there is 2 inches of ease built into the pattern instructions.

  • I have been wondering about this mystery for so long! Thank you! This is so helpful.

  • Thank you – this will save me from some of my kinda fails..

  • Oh my goodness! This is the first time I actually understood ease. Excellent explanation, thank you!

  • Thanks for clarifying this; sizing has been a big issue for me! I just finished my fabulous Crowberry (in a record 10 days!) and happily I got this one right! And I love it!!

  • As a cotton sweater knitter, I’ve learned to knit with less ease. Because cotton yarns stretch out as worn (and by the weight of the yarn itself), I make a smaller size than I would expect to make. And I always check the measurements of commercially-made garments with similar design features (cables, modified drop shoulders) to create my own schematic, and adapt the pattern to my needs. Some of my first cottons sweaters have “grown” over the years.

  • The other missing link in fitting is whether one’s total high bust (the real name of underarm measurement) is divided evenly between front and back by the side seams (or where they would be if knitting in the round). Most people of either sex over age 12 are not well served by front and back segments being the same size. We have rounded upper backs, narrow or wide shoulders, etc. Use the “crease to crease” upper chest front and back measurements to accurately place where shoulder joint really is, and if needed, knit a size larger or smaller for front, compared to back. Yeah, same can apply to hip area. Sweaters hang off the shoulders of bodies, so get the placement of the shoulder joint right and even a drop shoulder sweater will be comfortable and look good.

  • Very good information. The notion of ease has always confused me, and this answers my questions on that front. Because I’m pear shaped, I generally go by hip size and then scale down as I work my way up to the bust line so it fits well, especially across my narrow shoulders. It took a few tries before I got that method right, but then had to totally rethink it when knitting top down. After reading your article, I’m going to knit my next pullover based on my bust measurement and increase as I head toward my hips. Thanks for your insight!

  • Very helpful, thanks! I’ve always thought the bust measurement should be measured around the fullest part of the bust (in fact, many patterns state just that) but have scratched my head over the difference between the recommended size and what seem to be the measurements of my favorite actual garments. This would explain the discrepancy. Just to make sure–when you say underarm circumference, and make a distinction between that and the circumference at the fullest part of the bust, what part of the bust does the tape measure run across? Is it underneath the bust, or above it, nearer the shoulders?

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