Which is warmer — cashmere or merino wool?

1. The Science of Warmth (Loft & Crimp)

Warmth comes from trapped air, not the fiber itself.

• Cashmere: The fibers are extremely fine (typically 14–16 microns) and have a high degree of natural “crimp” (zigzag shape).³ When spun, these fibers interlock to form millions of tiny air pockets.⁴ This creates a high-loft “dead air” barrier that traps body heat very efficiently without adding weight.⁵

• Merino Wool: The fibers are thicker (typically 18–24 microns) and smoother. They pack down tighter, trapping less air than cashmere of the same weight.

2. The “Weight” Advantage

Because of its efficiency, a thin, lightweight cashmere sweater can keep you as warm as a thick, chunky merino sweater.

• The Selling Point: Cashmere allows you to layer without looking bulky.⁶ Merino requires more bulk to achieve the same insulation rating.

3. The “Active” Exception (Where Merino Wins)

While cashmere is warmer, Merino is the superior performance fiber.⁷

• Moisture Management: Merino wool is hydrophilic (water-loving) and moves sweat away from the body faster than cashmere.

• Durability: Merino fibers are more elastic and durable.⁸ If you hike or ski in cashmere, you will sweat, the fiber will get heavy, and the friction will cause it to pill or tear. Merino handles abrasion and moisture much better.⁹

Comparison Table for Your Customers

Summary

• If the goal is maximum warmth with minimum weight (standing at a bus stop, sitting in a cold office), Cashmere is the winner.¹⁰

• If the goal is warmth while moving (walking to work briskly, hiking), Merino is better because it regulates temperature without overheating or getting clammy.¹¹