Mercari’s Positive Impact (Avoided Greenhouse Gas Emissions)

According to the results of calculating the reduction contribution across six categories², researchers discovered that through Mercari transactions in both Japan and the US, we avoided approximately 610,000 tons of greenhouse gas emissions annually. The categories³ examined were Clothing; Sneakers; Electronics; Books, Magazines & Comics; CDs, DVDs & Blu-rays; and Bags (added to the calculations this year). This is equivalent to the volume of approximately 250 covered baseball stadiums⁴ or the amount of CO2 absorbed by approx. 69M cedar trees in one year⁵.

The life cycle of a new product generates environmental burden in many steps, from gathering the raw materials to disposing of the product. At Mercari, we believe that utilizing secondhand items in place of new items reduces this environmental burden. As such, we estimated the amount of purchases of new items that were avoided by transactions on Mercari and calculated roughly how much this contributed to reducing the environmental burden across society. We call this “avoided greenhouse gas (GHG) emissions.”

We use life cycle assessment (LCA) to calculate avoided emissions. LCA is a method of quantitatively evaluating the environmental burden of a product or service throughout its life cycle (production, distribution, consumption, and disposal).
We define avoided emissions as the difference in greenhouse gas emissions between two scenarios: one in which a consumer purchases a new item, and one in which a consumer purchases the same item secondhand on Mercari. Specifically, we calculate the environmental burden of the entire life cycle for a new item and the environmental burden of distribution and consumption for a secondhand item purchased on Mercari. We then calculate the difference between the two. Additionally, not all transactions of secondhand items contribute to reducing the amount of new items produced, so we incorporate the concept of a displacement rate. This rate is an estimate of the percentage of transactions on Mercari in which an item is purchased in place of a new item. The number is calculated based on the results of a user survey.

These calculation methods were designed by our R&D organization Mercari R4D in collaboration with These calculation methods were designed by our R&D organization Mercari R4D in collaboration with the University of Tokyo RIISE’s collaborative research division “Value Exchange Engineering.” ^6,7

In Japan alone, users avoided approximately 52,000 tons of apparel waste (by weight) by listing items they no longer needed on Mercari. This is equivalent to approximately 10% of the total 480,000 tons of apparel thrown away annually in Japan⁸.
By buying and selling no-longer-worn apparel on Mercari instead of throwing it away, users can reduce the burden on the environment and move closer to creating a circular economy.

1. US numbers were calculated independently for by referencing the calculations used as the basis for analyzing data for the Mercari app in Japan.
2. The calculation includes secondhand items purchased on the Japan and US Mercari marketplace apps for which transactions were completed from April 2023 to March 2024 in the following categories: Women’s Fashion, Men’s Fashion, Babies & Kids (the preceding three categories include the Sneakers category); Computers, Smartphones, and Tablets; Books, Comics & Graphic Novels, and Magazines; CDs, DVDs, and BDs; and Bags.
3.
– The amount of greenhouse gas (GHG) emissions avoided by reusing items in place of buying new items = Amount of GHGs generated by using new items – Amount of GHGs generated by reusing items = (Number of new items equivalent to secondhand items x GHG emissions generated by new items) – (Number of secondhand items x GHG emissions generated by secondhand items)
– The effect of greenhouse gas (GHG) emissions avoided by reusing electronics (extending their product use life) = Amount of GHGs generated by using only new items – Amount of GHGs generated by reusing items = (Number of devices when only using new items x GHG emissions generated by new items) – (Number of devices when using both new and secondhand items and extending the product use life x GHG emissions generated through using new and secondhand items)
4. Volume of CO2 equivalent to one covered baseball stadium: Approx. 2,436 t -CO2 (Volume of Tokyo Dome: 1.24M m3 = 1.24M kL, 1 mol = 22.4 L = 44 g – CO2, Source: Tokyo Dome webpage https://www.tokyo-dome.co.jp/faq/dome/)
5. From “How Much Carbon Dioxide Do Forests Absorb?” published on the website of the Forestry Agency (available only in Japanese) https://www.rinya.maff.go.jp/j/sin_riyou/ondanka/20141113_topics2_2.html
6. Summary of Mercari user survey
Apparel and Sneakers categories
– Period: January 30 to February 3, 2023
– Target: Users who listed or purchased items on the Mercari marketplace app in the apparel categories
– Method: Mercari app survey
– Number of respondents: Listers: 18,137, Buyers: 13,696
Electronics category
Period: January 19 to January 25, 2023
– Target: Users who listed or purchased an item on the Mercari marketplace app in an electronics category
– Method: Mercari app survey
– Number of respondents: Listers: 16,174, Buyers: 10,699
Books and music categories
– Period: June 26 to July 2, 2023
Target: Users who listed or purchased an item on the Mercari marketplace app in a books or music category
– Method: Mercari app survey
– Number of respondents: Listers: 4,264, Buyers: 2,812
7. The amount of GHG emissions generated from materials and energy used to calculate the amount of GHG emissions cited in this release were based on figures referenced mainly from the “IDEA v3.4” LCI database.
8. Calculated based on the number of items listed in the Women’s Fashion, Men’s Fashion, Babies & Kids categories for Mercari in Japan from April 2023 to April 2024. Figures for weight of apparel were referenced from Ministry of Economy, Trade and Industry data (Source: Ministry of Economy, Trade and Industry “Survey on Measures to Revitalize the Textile and Clothing Industry” https://warp.da.ndl.go.jp/collections/info:ndljp/pid/1621320/www.meti.go.jp/report/downloadfiles/g20523b01j.pdf)