Shoppers are voicing their frustration following a change that caused items being listed as the wrong size.
The popular resale platform has updated its measurement guidelines for female and kids' apparel but did not contact every member regarding the update.
Social Media Backlash
Numerous buyers and vendors are posting online saying Vinted listings now show a modified sizing category than originally posted because of the remapping.
The company said the revised method more closely matches similar services.
It has advised users to review their products and manually change the size when needed, resulting in member annoyance.
Measurement Approach Changes
Before the change, the sizes had both one number and one letter, like S/8 or M/10.
The revised method features a letter and a range such as S/UK 8-10.
For certain items, the measurements have been reclassified - such as a large size used to be a 12 but now shows as UK 16-18.
Shopper Accounts
A fashion influencer, who creates plus-size fashion videos, explained the modification "makes transactions more difficult".
"Few clothing companies classify XL as 20-22," as the platform currently indicates.
A different member, located in Scotland, explained products she uploaded featuring size 14 markings were displaying on the service as larger sizing 20-22.
"If buyers measuring 20-22 acquire them they may become frustrated," she stated.
Necessary Adjustments
Another shopper, from Derby, stated she felt frustrated due to the update requiring manual adjustment the sizing for "all her products".
"Personally, this is quite irritating, as I'm chronically ill and Vinted sales have been crucial after experiencing income reduction," she stated.
Marketplace Information
The app has more than 100 million members, including 18 million in the UK.
It has proved a popular alternative to second-hand platforms like eBay and Depop.
This represents another occasion when a surprising modification to the app has proved unpopular: earlier, Vinted reversed a change to its shipping options after backlash from users.
