A cotton sock takes 1 to 5 years to decompose. Pure cotton is a natural fibre that microbes can break down, but a sock is never pure cotton.
Why does it take this long?
The elastane in the cuff, synthetic reinforcement in the heel and toe, and the dyes all resist decomposition. In a wet environment the process slows further, and the stretchy parts can outlast the cotton by years.
Where it sits on the timeline
2 months
🍎 Apple core
20 years
🛍️ Plastic bag
1–5 years
🧦 Cotton sock
4,000+ years
🍾 Glass bottle
Greener alternative
Choose organic, undyed socks
Socks made from organic cotton without synthetic blends break down cleanly and skip the microplastic problem.
Frequently asked questions
How long does a cotton sock take to decompose?
A cotton sock takes approximately 1–5 years to decompose in nature.
Do cotton socks biodegrade?
The cotton portion does, but the elastic and synthetic reinforcements do not fully break down and leave microplastics behind.
Can old socks be recycled?
Yes — textile recycling programs accept worn socks. It's far better than sending them to landfill or nature.
Sources and methodology
Decomposition times are approximate and vary substantially with material composition and environmental conditions. See the methodology and primary references used for this guide.