Cotton T-Shirt

Product Profile

The cotton T-shirt is a single-layer knit garment weighing approximately 250 g, made from conventional (non-organic) cotton. This is the most produced garment type globally, with an estimated 2 billion units manufactured annually.

At 8.1 kgCO2e per unit, this is a conservative estimate assuming worst-case plausible conditions: conventional cotton grown in water-intensive regions, dyed with conventional reactive dyes, and manufactured on high-carbon grids.

The Cotton Supply Chain

Unlike electronics where semiconductors dominate, apparel emissions are spread more evenly across the supply chain:

1. Cotton cultivation (30% of total): Field emissions from irrigation energy, nitrogen fertilizer application (producing N2O, a potent GHG), and pesticide production. Conventional cotton uses ~150-200 kg N fertilizer per hectare.
2. Dyeing and wet processing (22%): The most energy-intensive stage of garment manufacturing. Heating large volumes of water for dye baths, washing, and finishing consumes significant thermal energy, often from coal or natural gas boilers.
3. Yarn spinning (15%): Ring spinning or open-end spinning of cotton fibers into yarn. Electricity-intensive process typically powered by the local grid.
4. Fabric production (12%): Circular knitting for jersey T-shirt fabric. Lower energy than weaving but still significant at scale.

Organic Cotton Comparison

Organic cotton reduces field-level emissions by eliminating synthetic fertilizers and pesticides, but the net benefit is smaller than commonly assumed:

• Organic cotton typically yields 20-30% less per hectare, requiring more land
• Reduced fertilizer eliminates N2O emissions but organic alternatives have their own footprint
• Net reduction estimated at 15-25% on the cultivation phase, or roughly 5-8% on total garment footprint

This is not reflected in the default score. Suppliers using certified organic cotton may submit evidence for a provenance override.

Provenance Override

Brands may override the default score by submitting:

• Verified organic cotton certification (GOTS, OCS)
• Factory energy audits showing renewable energy use
• Bluesign or OEKO-TEX certification for wet processing
• ISO 14067-compliant PCF covering the full garment supply chain