Most frequently used1 materials for t-shirts are cotton, polyester, viscose.
T-shirts are usually manufactured in China, Bangladesh, Vietnam, Turkey or India. 2
The average carbon footprint of a t-shirt is 7 kg CO2 equivalent (kgCO2e)3. The lowest is Cotton (recycled), made in Vietnam (5 kgCO2e), the highest is Cotton, made in India (10 kgCO2e).