Cotton vs Acrylic Yarn

The comparison

The one property everything else follows from

Cotton is hydrophilic and acrylic is hydrophobic. Cotton's cellulose structure carries polar groups that bond with water molecules, so water goes into the fiber. Acrylic's chains are non-polar, so water sits on the outside and in the gaps between stitches.

The textile industry quantifies this as commercial moisture regain, published for every fiber in ASTM D1909. Cotton's regain is several times acrylic's, which is why cotton is used almost exclusively for toweling and acrylic essentially never is.

Where cotton wins outright

• Dishcloths and washcloths. Absorbency, plus tolerance of a boil wash. See best yarn for dishcloths.
• Summer garments. Breathability. Acrylic worn in heat traps moisture against the skin.
• Market bags and totes. No stretch, so a loaded bag does not sag to the floor.
• Amigurumi. Crisp stitch definition, so you can see and count your stitches - see best yarn for amigurumi.
• Anything that will be ironed or washed hot. Acrylic will glaze.

Where acrylic wins outright

• Large blankets. A worsted-weight cotton blanket is genuinely heavy, and heavy enough to be unpleasant to sleep under.
• Children's garments. Cheap, machine washable, tumble dryable, and replaceable when lost.
• Quantity. Charity knitting, gift knitting, learning. Cost per yard is the lowest of any fiber.
• Colorwork on a budget. Acrylic is produced in vast color ranges at a price that makes buying six colors reasonable.
• Anything worn by someone avoiding animal fiber. Along with cotton, it is the main alternative.

Weight, which people underestimate

Cotton is denser than acrylic, so at the same yarn weight and the same gauge, a cotton fabric weighs more. Over a scarf that is irrelevant. Over a blanket it is the difference between cozy and oppressive.

It also drags. Cotton has no elasticity at all, so a heavy cotton garment stretches downward under its own weight and stays stretched. That is why cotton sweaters are usually knitted at a tighter gauge than wool ones and why cotton cardigans grow at the front edges.

The mercerized question

Not all cotton yarn behaves the same. Mercerizing treats cotton with caustic soda under tension, which swells and straightens the fiber permanently.

If a cotton yarn has been unpleasant to crochet with, it was probably untreated. A mercerized cotton is a noticeably different experience, and it is why best hook for cotton yarn treats them separately.

Where neither is the answer

Both fibers share one weakness: neither insulates when wet. Cotton absorbs water and then holds it against your skin; acrylic keeps it on the surface, in the same place. For anything worn outdoors in cold or wet conditions, wool is the fiber that solves the problem - see acrylic vs wool and best yarn for mittens and gloves.

They also share a virtue worth stating plainly: both are very low allergy risk. If a garment has to be worn by someone who reacts to wool, either fiber is a reasonable answer, and the choice is about the project rather than the person.

Blends

Cotton-acrylic blends exist and they behave more like the majority fiber than like a compromise. A 60/40 cotton-acrylic still absorbs; a 30/70 mostly does not. Read the percentages, not the name - the same advice our wool-acrylic blends page gives for the other combination.

The genuine advantage of adding acrylic to cotton is weight: an acrylic content lightens the fabric, which is why summer blanket yarns are so often blends.