How much carbon is a t-shirt?

A t-shirt is 7 kg of CO2 equivalent on average.

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).

50% of the carbon footprint comes from wet treatment.

Manufacturing a t-shirt involves different processes such as knitting & weaving, wet treatment or confectioning.
These processes require about 10 Kilowatt-hour (Kwh)⁴of energy. That is where the bulk of carbon emissions come from.

A t-shirt made in India has a carbon footprint 1.5x higher than a t-shirt made in Vietnam.

Countries rely more or less on fossil fuel to produce their electricity. That impacts the product carbon footprint.
For instance a t-shirt manufactured in India has a carbon footprint 1.5x higher than a t-shirt manufactured in Vietnam⁵.

Using recycled materials emits less carbon.

A t-shirt made of recycled materials tends to consume less energy and emits less carbon than a t-shirt made of non-recycled materials.
The difference is most notable between cotton and recycled cotton.

Footnotes

Draft PEFCR, Apparel and Footwear 2021, p. 58 ↩
UN Comtrade International trade in goods and services based, 2019 ↩
Carbonfact custom analysis, 2022 ↩
Base Impact, ADEME ↩
Our World in Data, 2021 ↩