Alpaca vs merino wool, with cashmere as the third option

The short version

If the recipient says wool makes them itch, buy alpaca. If the blanket is going to be used hard, washed often and sat on by a dog, buy merino. If neither of those is soft enough and the budget reaches it, buy cashmere and accept that it is the most delicate of the three.

That is the whole decision, and the rest of this page is the evidence behind it, because almost every claim made for these fibers in a product listing is either unverifiable or quietly wrong. The numbers below come from the sources listed at the bottom, not from a brand's own copy.

The one number that matters: fiber diameter

Softness is not a vague quality. It is almost entirely a function of how thick the individual hairs are, measured in microns, because a thicker hair is stiff enough to press into the skin rather than bend against it. Roughly 25 microns is where most people start to feel prickle. Everything else about these three fibers is secondary to that one number.

Read that table carefully, because it does not say what the marketing says. Good alpaca and good merino overlap almost completely. A fine merino at 19 microns is finer than a lot of commercial alpaca, and a top-grade alpaca is finer than a standard merino. Neither fiber is inherently softer than the other — the grade within each fiber matters more than the choice between them.

The itch question, and why alpaca usually wins it

Two separate things make wool itch, and people conflate them constantly. The first is diameter, covered above. The second is lanolin, the grease in sheep's wool, which is the usual culprit when somebody reacts to wool rather than merely finding it scratchy. Alpaca fiber is described as having essentially no lanolin, and that absence is where the hypoallergenic claim comes from.

Be precise about what that does and does not mean. It means alpaca is a sensible first try for someone who has given up on wool, because the most common irritant is simply not present. It does not mean alpaca is hypoallergenic in a tested, clinical sense — the claim rests on the absence of lanolin rather than on allergy data, and nobody has shown that no one reacts to alpaca.

The practical move is cheap: buy a scarf before you buy a blanket. A neck is the most sensitive place a fiber will ever touch, so a scarf settles the question for the price of a takeaway rather than the price of a bed blanket.

What alpaca marketing gets wrong

You will read everywhere, including in older copy on this site, that alpaca fiber is hollow and that this is why it insulates so well. The documented position is narrower than that. Medullated fibers — ones with a central core — do occur in alpaca, and when that core contracts it leaves air pockets that assist insulation. But medullation is mostly found in the coarser guard hairs, and it is treated as an undesirable trait in quality products, not a selling point. The fine fiber in a good alpaca blanket is largely not the hollow kind.

So the honest version is this: alpaca is described as warmer than sheep's wool and not prickly, and it insulates even when wet. Those are real properties. The tidy hollow-fiber explanation attached to them in product listings is an overstatement, and we would rather say so than repeat it. If a listing leans on the hollow-fiber story as its main claim, it is selling you physics it has not checked.

Warmth, weight, and which one you actually want on a bed

Alpaca

Warm for its weight and warm when damp, which is the property that matters in a cold house rather than on a mountain. The practical result is a blanket that feels lighter than it performs.

Merino

The all-rounder. Slightly heavier for the same warmth, far more available at every price, and the fiber with the deepest range of grades, so a merino blanket can be anything from scratchy to superb depending on the grade.

Cashmere

The softest and the most temperature-neutral: it is hygroscopic, absorbing and releasing moisture from the air, which is why it suits a person who overheats as much as one who is cold.

For a bed blanket, the number to look for is GSM — grams per square meter — and almost no listing gives it. When one does, it is telling you something real: around 350 GSM and above is a genuine winter weight, while a decorative throw is often half that. A listing that states the fiber and the GSM has told you more than a page of adjectives.

Durability, pilling, and the thing nobody mentions

This is where the ranking inverts, and it is the single most useful reason to choose merino over the other two. The finer a fiber is, the less abrasion it takes before it breaks and tangles into pills. Cashmere, being the finest by definition, is the first to pill where it rubs — the arm of a sofa, a seatbelt, a bag strap. Alpaca sits in the middle. Merino, especially at the medium grades, is the one that takes a decade of being sat on.

Construction matters as much as fiber here. A tightly cabled Aran knit is dense and holds its shape; a loosely spun giant-yarn blanket snags on a ring the first week. If the gift is going to a house with children, a dog, or furniture with wooden arms, weight the decision toward merino and toward a tight knit or a close weave.

Washing, which is where most of these blankets die

Every fiber on this page is protein, not plant, and protein fibers felt when you combine heat, water and agitation. That is the whole mechanism behind a three-figure blanket coming out of a machine at doll size, and it is not reversible.

1. Do not put any of them in a hot wash. If the label says hand wash or dry clean, that is a load-bearing instruction rather than a legal disclaimer.
2. Wash rarely. Wool is naturally odor-resistant and most blankets need airing far more often than they need washing. Hanging one outside on a dry day does most of the work.
3. Dry flat, never hung. A wet wool blanket is heavy enough to stretch itself out of shape over a line.
4. Spot clean first. Nine times out of ten a mark comes out with cool water and patience, and that avoids the risk entirely.

Wool and fiber care is the full routine, including what to do about moths, which are a bigger threat to all three of these fibers than any amount of normal use.

Price, and what you are actually paying for

The supply side explains most of the pricing. Cashmere comes from the undercoat of a goat, combed out by hand, at roughly 150 grams per animal per year. That is why a cashmere throw costs what it does: the raw material is measured in handfuls per goat per season. Merino is shorn by the fleece and farmed at enormous scale, which is why merino is the fiber with a genuine budget end. Alpaca sits between the two, with far less global production than merino and far more than cashmere.

In qualitative terms: at the price of one cashmere throw you can usually buy a merino bed blanket, and at the price of one fine alpaca bed blanket you can buy two or three merino throws. All three are objects that should last fifteen years, so the sensible way to compare them is cost per year rather than cost per blanket — and on that basis the most expensive mistake is not choosing the dearer fiber, it is choosing a blanket that gets folded into a cupboard because the color was wrong.

How to read a fiber listing

Four checks, in order, and they will filter out almost everything dishonest in this category.

1. Is there a percentage? US law requires wool products to carry their fiber content. A listing that says alpaca blend without a number is usually mostly acrylic, and a listing that says merino-style or cashmere-feel contains neither.
2. Is there a measurement? Dimensions in inches or centimeters, and ideally a GSM. Throw and blanket are not sizes.
3. Does the price make sense for the fiber? A three-figure fiber cannot be sold as a two-figure blanket at sofa size. When it is, the fiber is not what the title says.
4. Who made it, and does it say where? Hand woven in Nepal, knitted in Ireland, woven by a Guatemalan cooperative — specific provenance is checkable and vague provenance is not. The same test runs across every craft on this site: see spotting resold mass production.

Which one, for which gift

A summary for the person who scrolled to the bottom. Alpaca for someone who has decided wool is not for them, for a cold sleeper, and for a gift that should feel like a serious object. Merino for a household rather than a person: it is the one that survives being used by everybody, and it is the only one of the three with a credible budget end. Cashmere for a reader, a sofa, and someone who notices textiles, and not for a house where it will be sat on by something with claws.

If you are buying a blanket as a gift for a couple rather than a person, engagement gifts covers how a large textile fits alongside the smaller things, and knit blankets and throws and handwoven throws are the full product lists once you have settled on a fiber.