We all have different arm lengths. In my patterns, I make sure to offer you the possibility to easily adapt this length to your measurements. The technique might be a bit surprising at first glance, which is why I decided to write this article so you can better understand the principle. And what’s more, it might make you want to use the technique on other patterns!
The principle: respecting the natural curve of the arm
An arm is not a cylinder. It tapers gradually from the underarm to the wrist, and it’s the forearm that tapers the most. So for classic sleeves with regular decreases, this is exactly where the decreases make the most sense visually: the sleeve hugs the shape of the arm instead of simply narrowing linearly over its entire length.
So between the underarm and the elbow (A), there isn’t much difference, but between the elbow and the wrist (B), that’s where it all happens.
In practical terms, this means that the entire decrease sequence must end at the wrist to follow the natural curve of your arm. For the same size, we aren’t going to vary the length of the section with decreases because that is a bit complex; instead, we vary the length of the section knitted just before, without decreases (part A of the diagram).
Often in a pattern, you’ll be told to knit after the decreases until X cm less (X being the wrist cuff), but that results in a straight length at the end of B.
The sentence you see in my patterns
For sleeves worked from the top down, right after the underarm, I will give you an instruction like:
Knit until 36 cm less than the desired length, then begin decreases.
This sentence has already left more than one person perplexed (hello to my testknitters!):
36 cm, isn’t that a lot before starting decreases? -> we are indeed talking about 36 cm less than the desired length
But then, what do these famous 36 cm less correspond to?
Well, in reality, it is the length including the decreases AND the cuff, part B of our diagram.
So if you follow your gauge correctly and you know your arm length from the underarm, you will have the best-fitting sleeves of all your knits!
How to measure your desired sleeve length
Measure the arm length from where your underarm falls down to the wrist (or to where you want the sleeve to end). Note: to get a good fit for your underarm, I recommend finishing the neckline first.
It is this measurement, yours, that replaces the “standard” length that might be indicated in the pattern measurements.
A good habit: measure directly after putting your sweater on.
This measurement corresponds to measurement A+B in the diagram.
How to apply the calculation
The number of centimeters indicated in the pattern (the “36 cm less”), as we said, corresponds to the entire portion containing the decrease sequence, down to the wrist (B). This is a fixed value, given by the pattern; it does not change.
What changes is the part you knit just before (part A), without decreases:
Section without decreases A = your desired sleeve length A+B − the desired length less indicated in the pattern (B)
An example to make it concrete: if the pattern says “knit until 36 cm less than the desired length” and your desired sleeve length is 42 cm:
42 (A+B) – 36 (B) = you knit 6 cm straight after the underarm
ATTENTION! Don’t forget your gauge. If you know that after blocking, your number of rows/rounds changed significantly per 10 cm, do a quick cross-multiplication:
6 cm desired x number of rows/rounds per 10 cm / 10 = the number of rows/rounds you will knit before the decreases
Once you have knitted the 6 cm and your decreases, only the cuff remains. I indicate here how much length is left to knit. If you feel like your sleeve won’t end exactly at your wrist, there are 2 possibilities: blocking will work its magic, or you can add or remove a few rounds as needed, this will be an adjustment after the decreases, but so much more discreet than if it were over several centimeters!
I deliberately choose a fairly short length compared to standards for the entire decrease section. The goal is that even if your arm length is short, you can still complete the entire decrease sequence while having room to adapt to your body shape.
Why it works for everyone
This method works regardless of arm length because you never touch the decrease sequence itself: it remains identical to the pattern. You only adjust the length of the straight section, the one at the top of the arm, which doesn’t need to follow a precise curve. It’s the easiest part to shorten or lengthen without disrupting the shape of your arm.
This is also what gives a more natural drape to a fitted sleeve. Having a straight section, without decreases, from the underarm to the start of the decreases, allows the sleeve to follow the natural volume of the upper arm before hugging its curve toward the wrist. A sleeve that decreases over its entire length tightens the knit from the start and gives a more artificial look, less faithful to the shape of the arm.
In summary
- Measure your desired sleeve length, from the underarm to the wrist (A+B)
- Locate the “X cm less” indicated in your pattern (B), right after the underarm
- Knit straight for: desired length − X cm = A
- Start the pattern’s decrease sequence. It ends at your wrist.
Once you understand the principle, it’s a reflex that applies to any pattern built on this model, not just mine. You identify how many rows/rounds you are asked to decrease, and using the gauge, you find the length that represents. Same with the cuff. And presto, you have everything you need to adapt to your arm length.
Any questions about adjusting your sleeves on a particular pattern? Write to me, I’m always up for helping you find the right fit.