Members of the platform have expressed outrage due to a modification that led to products showing incorrect sizing.
This online marketplace has altered its measurement guidelines for female and kids' apparel without notifying all users about the change.
Numerous buyers and vendors are posting online saying Vinted listings now show an altered size classification than originally posted due to the recalibration.
Vinted explained the updated approach better aligns with similar services.
It has advised users to review their products and manually change the size where appropriate, causing user dissatisfaction.
Earlier, the sizes had both numerical and alphabetical indicators, for instance S/8 or M/10.
The new system has a letter with a size spectrum for example S/UK 8-10.
For certain items, the sizing has been recategorised - such as a large size was previously a 12 but is now a UK 16-18.
One content creator, who produces content about larger sizing, stated the update "complicates both purchasing and selling".
"Rarely do manufacturers list XL as sizes 20-22," which is what Vinted now does.
Stephanie Gallen, located in Scotland, stated items she posted featuring size 14 markings were appearing on the platform as larger sizing 20-22.
"If anyone [who is] size 20-22 buys them they may become frustrated," she explained.
Charlotte Lunn, located in England, said she had been left angered because the modification necessitated personal updates the measurements for "each individual item".
"For me this is particularly frustrating, as I'm chronically ill and selling on Vinted has been paramount for me since losing part of my income," she explained.
The service features exceeding 100 million members, comprising 18 million UK members.
It has proved a popular alternative versus similar marketplaces including eBay and Depop.
This is not the initial instance when a surprising modification to the app has proved unpopular: earlier, the platform withdrew an update concerning shipment methods due to shopper criticism.
A London-based journalist with a passion for uncovering hidden stories and sharing authentic British experiences.