Breathability and what the word actually covers

Short answer: Breathability is two things: how much air can pass through the fabric, and how well the fabric moves moisture. The two do not always go together.

Air permeability

A loosely woven or knitted fabric lets air through and cools by moving warm air away from the skin. A dense fabric does not, whatever fibre it is made from. Construction matters more than fibre here.

Moisture transport

The other half is about moving sweat. Here the fibre matters most. Bamboo viscose absorbs moisture into the fibre and releases it to the air, while polyester carries it along the surface. See bamboo underwear for women.

Why a garment can be both

A densely knitted bamboo fabric can move moisture well and still feel warm, because no air gets through. A loosely woven fabric can do the opposite. Look at both fibre and density. See bamboo t-shirts for women and bamboo clothing for women.

Frequently asked questions

Is bamboo viscose breathable

On moisture transport yes. On air permeability it depends on how densely the fabric is knitted.

What is most breathable in summer

A loosely woven fabric in a fibre that absorbs moisture, meaning linen or a light bamboo fabric.

Can a fabric be too breathable

In cold weather yes. It then carries heat away faster than the body can replace it.