Shoppers are voicing their frustration following a change that caused listings displaying inaccurate size information.
The second-hand shopping app has revised its size classifications for female and kids' apparel but did not contact all users about the change.
Numerous buyers and vendors are expressing on platforms claiming that product pages now present a modified sizing category compared to what was initially listed due to the recalibration.
The platform stated the revised method more closely matches similar services.
They have suggested members to check their listings and update the measurements by hand where appropriate, causing user dissatisfaction.
Earlier, the sizes had both one number and one letter, such as S/8 or M/10.
The updated approach includes a letter and a range such as S/UK 8-10.
For certain items, the sizing has been recategorised - for example a size L was previously a 12 but currently displays as UK 16-18.
A fashion influencer, who creates plus-size fashion videos, explained the modification "makes transactions more difficult".
"Not many brands say XL is a 20-22," as the platform currently indicates.
Stephanie Gallen, from Glasgow, stated items she posted on Vinted with size 14 labels were displaying on the service as larger sizing 20-22.
"If buyers measuring 20-22 acquire them they may become frustrated," she stated.
A different user, located in England, said she had been left angered because the modification necessitated personal updates the sizes on "every single listing".
"This situation is especially annoying, because of my ongoing medical condition and platform income has been essential for me since losing part of my income," she said.
The app has more than 100 million shoppers, including 18 million in the UK.
It has proved a popular alternative compared to resale services such as eBay and Depop.
This is not the initial instance when a surprising modification to the app has proved unpopular: last year, Vinted reversed a change regarding delivery choices following member complaints.
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