Worsted weight yarns and aran weight yarns are often thought to be interchangeable, but they’re actually different yarn weights.
Aran weight yarn is thicker and often loftier than worsted yarn. It’s often knit on 5mm needles with a gauge between 4-4.5 stitches per inch.
To make matters more confusing, aran yarn is sometimes called “heavy worsted” or “10-ply yarn.”
Another consideration is that in the UK, the term “aran” is more widely used than “worsted” to refer to medium weight yarns. So, a worsted yarn may be categorised as aran weight in the UK.
For this reason, if you’re using a UK knitting pattern, consider trying worsted weight yarns even if the pattern calls for aran weight.
Can You Substitute Aran for Worsted Weight Yarn?
An aran weight is generally heavier than worsted weight yarn, resulting in a smaller gauge. For instance, an aran yarn may have a gauge of 16 sts = 4” while worsted yarn could have a gauge of 18 sts = 4”.
This difference may not seem like a big deal, but if you’re knitting a large number of stitches, the two-stitch difference will start to compound.
For instance, let’s say a baby blanket pattern calls for worsted weight yarn with a gauge of 18 sts = 4”.
The pattern requires casting on 200 stitches. Using the correct gauge, the finished measurement will be 44.5”.
Let’s say you’re looking to substitute aran yarn with a gauge of 16 sts = 4”
Using aran yarn, the blanket will be larger than the pattern’s finished measurements. Because of the gauge difference, it will be 50” instead of 44.5”. That’s almost a 12% difference!
For items like blankets, sizing may not matter very much. But when it comes to garments or accessories for the body, a few inches is the difference between one or two dress sizes.
Ultimately, the best way to decide on yarn for a pattern is to swatch the yarn. Ensure that your gauge matches the pattern’s gauge, troubleshooting with different sized needles or yarn weights if needed. The other option is to re-work the pattern to fit the gauge you have.
What is Worsted Yarn Used For?
Medium weight yarns like worsted and aran yarns are the most popular among knitters. It’s not hard to see why!
These yarns knit up quickly and provide both warmth and drape. Worsted and aran weight yarns are ideal for garments like sweaters and cardigans as well as accessories like scarves and mittens and home decor like pillows and blankets.
Worsted and aran are true all-purpose yarns!
Favorite Worsted and Aran Yarns
I’ve worked with a lot of medium-weight yarns in my time, and I have a few firm favorites. Allow me to share them with you!
Malabrigo Worsted is my go-to choice for single-ply worsted yarn. Spun with Uruguayan merino, it’s as soft as a cloud and a total joy to knit with. The yarn is kettle-dyed in beautiful tonal and variegated colors. This is the iconic yarn that started my love affair with Malabrigo. 10/10 would recommend!
Debbie Bliss Cashmerino Aran combines super soft merino with the lusciousness of cashmere. It’s gentle on the hands and glides through needles like a dream. This gorgeous yarn is machine-washable and comes in a range of beautiful colors, from pretty pastel pink to deep charcoal and rich aquamarine.
My favourite budget-friendly worsted yarn is Knit Picks Swish Worsted. Spun in fine superwash merino, it’s super soft, machine washable and comes in a large selection of colors.