Calculation formulas
Initial purchase CO2 emissions saved
Average weight of garments (kg) × average carbon emissions of material types (kg CO2-eq) × replacement rate (0.3)
Re-donation CO2 emissions saved
Average weight of garments (kg) × average carbon emissions of material types (kg CO2-eq) × donation and use cycles (5) × replacement rate (0.3)
The saved carbon emissions formulas were created using a replacement approach. These calculations assume that every reuse of a garment avoids a proportion of the manufacturing of a new garment. They use literature-backed approximations while preserving accuracy, allowing the saved carbon emissions from each Worthwhile Wardrobe garment purchase to be communicated transparently.
The calculations take place in two stages: the carbon emissions saved through the initial purchase and the cumulative carbon emissions saved through the re-donation of garments. The initial purchase formula calculates the emissions avoided through a single garment purchase from Worthwhile Wardrobe. The re-donation formula calculates the additional emissions avoided by keeping a garment in circulation for a total of five donation and use cycles.
Calculation parameters
Replacement rate
The replacement rate is set at 0.3, reflecting the assumption that 30% of second-hand garment purchases from Worthwhile Wardrobe directly replace the production of a new garment. This figure was selected towards the lower end of the ranges presented in existing literature, including Jučienė et al. (2025), to reflect the scope for improvement within the second-hand formalwear market.
Donation and use cycles
Each garment is assumed to complete a maximum of five donation and use cycles. This assumes that a garment can remain in good condition and be used by five different people. This figure reflects the life cycle of garments and highlights how re-donation preserves their potential for future reuse. Although existing literature shows that casual dresses may be used more than five times by their first owner, including Klooster et al. (2024), this project focuses on second-hand occasion wear and therefore uses a conservative estimate. In practice, the number of uses could be higher.
Average weight of garments
Two different tags were created for this project: one for occasion and formal dresses and one for wedding dresses. This separation reflects the significant difference in the average weight of these garment types.
- Occasion and formal dresses: 1 kilogram
- Wedding dresses: 4 kilograms
These figures were obtained through industry-informed approximations.
Table of materials
| Material type | Cradle-to-grave emissions, including use and end-of-life |
|---|---|
| Silk | Approximately 80.9 kg CO2-eq per kg |
| Wool, worsted | Approximately 50 kg CO2-eq per kg |
| Cotton | Approximately 20 kg CO2-eq per kg |
| Wool-polyester blend | Approximately 25 kg CO2-eq per kg |
| Polyester | Approximately 40 kg CO2-eq per kg |
| Viscose, or rayon | Approximately 20 kg CO2-eq per kg |
To provide a realistic assessment, the carbon emissions associated with the production of different material types were quantified using a life cycle assessment approach based on data from existing literature. The materials commonly used to manufacture formalwear, occasion wear and wedding dresses were identified before the associated emissions data were gathered.
The calculations use a weighted average of the emissions associated with these materials, which is 39.40 kg CO2-eq per kg. Other materials commonly used in formalwear and wedding dresses, including lace and chiffon, were not listed separately because they can be produced from several of the materials included in the table.
Bibliography
Sources for the table of materials
- Bianco, I. et al. (2023). Environmental Impacts in the Textile Sector: A Life Cycle Assessment Case Study of a Woolen Undershirt.
- Demirdelen, T. et al. (2023). Investigation of the Carbon Footprint of the Textile Industry: PES- and PP-Based Products with Monte Carlo Uncertainty Analysis.
- Fonseca, A. et al. (2023). Systematic Insights into a Textile Industry: Reviewing Life Cycle Assessment and Eco-Design, Literature Review.
- Petchchedchoo, P. et al. (2024). Analysis of the Carbon Footprint of Academic Gowns: A Case Study of Thai University.
- Rosa, A. D. L. et al. (2019). Comparative Life Cycle Assessment of Cotton and Other Natural Fibers for Textile Applications.
- Tekin, P. et al. (2024). A Life Cycle Analysis of a Polyester-Wool Blended Fabric and Associated Carbon Emissions in the Textile Industry.
- Wang, C. et al. (2015). Carbon footprint of textile throughout its life cycle: a case study of Chinese cotton shirts. Journal of Cleaner Production.
- Wiedemann, S. et al. (2020). Environmental impacts associated with the production, use, and end-of-life of a woollen garment.
Sources for comparisons
- Greenhouse Gas Emissions from a Typical Passenger Vehicle, US Environmental Protection Agency (2025). https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle
- Bernet, R. (2024). How much CO2 does a tree absorb? https://onetreeplanted.org/blogs/stories/how-much-co2-does-tree-absorb
- Carbon Emissions Saving Tool. https://carbon.manchester.ac.uk/
