In short:
- Cashmere is the finer of the two: 14 to 17 microns average diameter depending on the goat breed, against 15.6 to 20 microns for superfine and fine merino.
- With the same knit thickness, warmth is close: fibres conduct heat 5 to 20 times better than air, and the trapped air is what insulates.
- A cashmere goat yields 150 to 250 g of down a year, a merino sheep 3 to 6 kg of raw wool: that is where the price gap comes from.
- Merino copes better with daily wear and comes in machine-washable versions; cashmere pills sooner because its fibres are short.
Cashmere vs merino for a sweater comes down to how you will wear it. For the softness and lightness of a winter sweater worn with care, pick cashmere. For an everyday sweater that handles sweat and washing, pick merino wool. Both are natural fibres made of keratin. What separates them can be measured in microns, in grams per animal and in minutes spent on care.
Cashmere and merino in figures: comparison table
| Criterion | Cashmere | Merino wool |
|---|---|---|
| Animal | cashmere goat (undercoat down) | merino sheep (fleece) |
| Harvest | combing or shearing during the spring moult (March to May in the Northern Hemisphere) | shearing once a year, sometimes more |
| Average fibre diameter | 14 to 17 µm depending on breed; 19 µm at most for the name in the United States | 15.6 to 18.5 µm (superfine), 18.6 to 20 µm (fine), up to about 24 µm |
| Yield per animal per year | about 150 to 250 g of down | 3 to 6 kg of greasy wool (Saxon merino) |
| Water vapour absorption | hygroscopic fibre | almost a third of its weight |
| Pilling | more frequent, linked to short fibres | rarer, staples of 65 to 100 mm before spinning |
| Care | hand wash or cold wool cycle, flat drying | same; machine wash possible if the wool is “superwash” treated |
| Name on the label (EU) | “cashmere”, with or without “wool” or “hair” | “wool” |
| Price | high | more affordable |
Sources: Regulation (EU) No 1007/2011 for fibre names, 16 CFR § 300.19 for the US definition of cashmere, and the studies cited below for measurements.
Cashmere goats and merino sheep: two fibres, two origins
Cashmere comes from the down of the cashmere goat. It is the very fine undercoat that protects the animal through winters on the high plateaus of Central Asia. In spring, during the moult, herders comb it out, then the down is separated from the guard hairs, long stiff hairs that never end up in a sweater. China and Mongolia lead world production, according to the encyclopedia entry on cashmere.
Merino wool comes from the fleece of merino sheep. The breed originated in the Iberian Peninsula in the Middle Ages; Australia turned it into its great speciality from the 19th century onwards. Unlike the goat, the merino grows a fleece that never stops growing and must be shorn every year.
What the label tells you
In Europe, Regulation (EU) No 1007/2011 reserves the word “wool” for fibre from sheep’s fleece. Cashmere sits on another line, with the fine animal hairs (alpaca, camel, mohair, which comes from the angora goat, and others), and may be labelled “cashmere”, “cashmere wool” or “cashmere hair”. The terms virgin wool and fleece wool only apply to wool never used in a finished product before; in a blend, it must make up at least 25% of the weight.
In the United States, the rule is more precise about fineness: the name cashmere requires an average diameter of 19 microns or less, with no more than 3% by weight of fibres over 30 microns (16 CFR § 300.19).
Fineness and softness: what the microns say
The softness of a sweater depends first on the diameter of its fibres, given in microns (thousandths of a millimetre). A study published in 2025 in Frontiers in Veterinary Science measured an average of 14.13 µm for cashmere from the Alpas breed in Inner Mongolia, and 17.29 µm for ordinary cashmere (Frontiers, 2025).
On the sheep side, the merino wool grades run from ultrafine (up to 15.5 µm) to superfine (15.6 to 18.5 µm) and fine (18.6 to 20 µm), then medium and strong grades above that. Crossbred wools go to 27 µm and beyond.
In practice, a superfine merino at 17 µm and an ordinary cashmere at 17 µm feel very close under the fingers. The number matters more than the name of the fibre.
Itchy wool and sensitive skin
The feeling of itchy wool comes from thick fibres that prick the skin instead of bending. A Deakin University study of 177 knitted garments from shops found that mean fibre diameter had the strongest effect on this sensation, and that rib knits felt pricklier than single jersey (Deakin, International Journal of Clothing Science and Technology). For sensitive skin, go for cashmere or superfine merino, knitted in jersey rather than rib.
Warmth, breathability and temperature regulation
Which sweater keeps you warmer? With the same knit thickness and density, the gap is small. Fibres conduct heat 5 to 20 times better than air, and the air held in the yarns and the knit is what makes a garment insulating (Materials, 2023). A chunky merino sweater will therefore be warmer than a fine cashmere one.
Cashmere wins on lightness: being finer, it makes a fluffier yarn for a given weight, which explains its reputation as warm and light at once.
Merino stands out for breathability and temperature regulation. Wool can absorb almost a third of its weight in water vapour, which reduces the clammy feeling when you move from a cold street to a heated office. Cashmere is hygroscopic too. On odour resistance, work by Rachel McQueen’s team at the University of Alberta found much stronger odour in worn polyester than in wool and cotton, a result recalled in a 2018 paper (Clothing and Textiles Research Journal, 2018).
By season, a fine merino in light jersey works from autumn to spring, alone or as a base layer, while cashmere comes into its own in the depths of winter.
Pilling and durability
Pills form when short fibres migrate to the surface of the knit and roll up under friction. A study published in Fibers and Polymers on cashmere knits attributes pilling mainly to fibre length, especially fibres under 7.5 mm, more than to yarn twist or knit density (Li and Zhou, 2006).
Cashmere down is short by nature. Merino staples measure 65 to 100 mm before spinning, according to the entry on merino sheep. The result: with comparable yarn, merino offers better durability against the rubbing of a bag strap, a seat belt or a chair back.
To remove pills, use a sweater comb or a fabric shaver, held flat on the knit, and never pull the pills off.
Care: hand washing, wool cycle and flat drying
Cashmere and merino react the same way to hot water and agitation. Their fibres are covered in scales that slide more easily in one direction than the other: with friction, water and heat, they lock together and the knit shrinks for good. This is felting. Triggered on purpose, the same process produces boiled wool, dense and wind-resistant. Industrial chlorine-Hercosett treatments, known as “superwash”, coat these scales and make wool machine-washable; a 2019 review describes them as the most effective but polluting (Journal of Advanced Research, 2019). You mostly find them on merino.
The safest care routine for both fibres:
- Read the care label: its symbols follow the international standard ISO 3758.
- Prefer hand washing, in cold or lukewarm water (30 °C at most), with a wool detergent, without rubbing or wringing.
- Only use the machine’s wool cycle if the label allows it, with the sweater inside out in a mesh bag and the lowest spin.
- Rinse at the same temperature as the wash: a temperature shock on wet wool speeds up felting.
- Press the sweater in a towel, then dry it flat, away from a radiator. Never tumble dry unless the label says so, never hang it (the knit stretches).
- Store it folded, clean and dry, between seasons.
Price, production and ethics
The price of cashmere comes first from the animal’s yield. A cashmere goat produces 150 to 250 g of down a year depending on the breed (encyclopedia entry on the cashmere goat), while a Saxon merino sheep gives 3 to 6 kg of greasy wool. It takes the down of several goats to make a single sweater. World sheep wool production reached about 1.98 million tonnes of greasy wool in 2024 (entry on wool), on a different scale altogether from cashmere volumes. That small volume explains the luxury image of cashmere.
On ethics and animal welfare, merino raises the question of mulesing: removing strips of skin around the sheep’s breech, practised in Australia to prevent flystrike. New Zealand has banned it since 1 October 2018 (entry on mulesing). If this matters to you, look for a “non-mulesed” mention or an animal welfare certification on the product page.
At the end of their life, both fibres are biodegradable: keratin breaks down in soil, and a 2022 study measured the drop in keratin content of buried wool fibres (Journal of Ecological Engineering, 2022). Dyes and anti-felting treatments can change that speed.
Which sweater to choose for your use
- Everyday sweater (office, commuting, frequent washing): a fine merino of 18 to 20 µm, in jersey, ideally treated for the machine.
- Sensitive skin: cashmere or a superfine merino under 18.5 µm, in jersey.
- Winter weekend sweater, for softness and lightness: cashmere, in a thick knit if you want warmth.
- Travel or physical activity: merino, for how it handles moisture and odour.
- Wool and cashmere blend: read the percentage. With 5 or 10% cashmere, you are mostly wearing a wool sweater.
To compare specific models, our guide to the best wool and cashmere sweater brands for women lists the compositions each brand publishes. Before ordering a cashmere sweater from a foreign site, keep the women’s size conversion chart for France, the UK and the US at hand: a sweater that cannot go in the machine is a hassle to send back. And to style it, a fine cashmere tucks neatly into wide-leg or palazzo trousers, whose loose line balances a close-fitting knit.
One last rule of thumb: if you plan to wear the sweater more than two days a week, go for merino.