How To Lengthen or Shorten The Sleeves On A Top Down Knitted Sweater

Have you ever knitted a garment and the sleeves have turned out either too long or too short? Or perhaps you’ve tried to lengthen or shorten the sleeves but the fit hasn’t been right afterwards? I’ve got you sorted – here’s a handy explanation of how to adjust the sleeve length, as you’re knitting, to ensure a perfect fit!

Whether you’re lengthening or shortening the sleeves on a top down knit, it’s a good idea to have knitted the body first and to have blocked your knitting (if you’re not sure what this means, read this blog post here). This is super helpful because we’ll measure the sleeve length from the underarm of the sweater and doing this once the body is blocked, will be much more accurate than unblocked.

Firstly, try on your sweater and using the measurement in the pattern’s schematic, work out if the sleeve is going to fit. If not, measure roughly how much longer or shorter you need the sleeves to be to get the fit that you’d like. Make a note of this number (cm or inches), remembering to take account of the cuff depth.

Secondly, find the gauge information in your pattern and look at the row/round gauge. For this example, I’ve used my Corra Linn Sweater pattern (link to Ravelry), where the round (row) gauge is 33.5 rounds to 10cm in garter stitch, worked in the round.

To work out how many rounds you need to add (to lengthen) or take out (to shorten), you need to do a little bit of maths:

  • Round Gauge is 33.5 rows to 10cm
  • Firstly, work out the number of rounds that there are in 1 cm of knitting: divide the number of rounds by 10cm; in this example 33.5 / 10 = 3.35 (I.E. 1cm = 3.35 rounds)
  • In this example, you’re going to add 5 cm to the length of my sleeve, so you multiply 3.35 rounds by 5cm = 16.75 rounds, which you can round up to 17 or down to 16 depending upon my pattern.

Thirdly, you now need to distribute these extra rounds throughout the sleeve decreases. If you just add extra rounds on the end of the sleeves after all the decreasing has happened, then the sleeves may be too narrow on your forearms.

Likewise, if you need to make the sleeve 5cm shorter, you need to knit 16 rounds less, but they need to be ‘taken out’ evenly across the length of the sleeve, so that the sleeve is kept in proportion with your arm.

Have a look at how many decrease rounds you need to work in your pattern. For this example, the pattern says you need to work 14 decrease rounds, each with 5 non-decrease rounds between them, and then 2 decrease rounds with 11 non-decrease rounds between (16 decrease rounds in total).

You need to knit 16 extra rounds so it would make sense to add 2 extra rounds into every second sets of decreases, meaning you’d work as so:

  • 1 dec round, 7 non-decrease rounds
  • then …
  • 1 dec round, 5 non-decrease rounds
  • then …
  • rep those two sets of decreases 7 times in total = 14 decreases, 14 extra rounds worked
  • then …
  • 1 dec round, 13 non-decrease rounds
  • then …
  • 1 dec round, 11 non-decrease rounds
  • In total = 16 decreases (as per pattern), with 16 extra rounds worked = approximately 5cm added to length

Likewise, if you were going to make the sleeves shorter by 16 rounds, you would work 2 less non-decrease rounds in-between every second decrease, to make sure that you’re keeping the proportions of the sleeve in place.

As you knit, keep trying on your garment and adjusting the sleeve if you need to. Remember that your gauge might change once you block the sleeves and that when you start moving around a sleeve will often shift up your arm, thereby appearing shorter. If you’re not sure whether the length is right, then you might like to thread the sleeves stitches onto a waste piece of yarn and block it to check. Then you can always knit a bit more, or take it back, before adding the cuff.

Looking for top down sweater patterns? The featured pattern here is Corra Linn, which is coming out soon – sign up to my mailing list to receive 15% off when it’s released!

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