Members of the platform have expressed outrage after an update resulted in items being listed as the wrong size.
This online marketplace has revised its size classifications for women's and children's garments but did not contact all users about the change.
Countless users and merchants have taken to social media saying Vinted listings now show an altered size classification versus the original listing due to the recalibration.
Vinted explained the updated approach better aligns with other platforms.
They have suggested members to check their listings and adjust the sizing manually if necessary, resulting in member annoyance.
Earlier, the measurements included one number and one letter, such as S/8 or M/10.
The new system has an alphabetical indicator and numerical range like S/UK 8-10.
For certain items, the measurements have been reclassified - such as a large size was formerly size 12 but now shows as UK 16-18.
One content creator, who creates plus-size fashion videos, explained the modification "makes transactions more difficult".
"Few clothing companies classify XL as 20-22," which is what Vinted now does.
Stephanie Gallen, from Glasgow, said garments she listed with size 14 tags were showing in the marketplace as size 20–22.
"If buyers measuring 20-22 acquire them they're going to be very disappointed," she stated.
Charlotte Lunn, based in Derby, stated she felt frustrated due to the update requiring manual adjustment the measurements for "each individual item".
"Personally, this is quite irritating, because of my ongoing medical condition and platform income has been essential following partial earnings loss," she said.
The service features exceeding 100 million shoppers, with 18 million British users.
It has emerged as a preferred choice compared to resale services such as eBay and Depop.
This isn't the first time where an unanticipated change within the service has received backlash: last year, Vinted reversed a change to its shipping options after backlash from users.
Maya Chen is an urban planner and writer with over 10 years of experience in sustainable city development projects across North America.