Shoppers are voicing their frustration after an update resulted in items being listed as the wrong size.
The popular resale platform has updated its measurement guidelines for women's and children's clothes but did not contact all shoppers about the modification.
Many shoppers and sellers are posting online stating that platform listings now display a modified sizing category versus the original listing because of the remapping.
Vinted explained the updated approach better aligns with other platforms.
The platform has recommended to review their products and adjust the sizing manually where appropriate, which has left users frustrated.
Earlier, the measurements included one number and one letter, like S/8 or M/10.
The new system has an alphabetical indicator and numerical range such as S/UK 8-10.
In some cases, the size labels have been reassigned - like an L measurement was previously a 12 but currently displays as 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," the way the service now categorizes.
Another user, located in Scotland, explained products she uploaded with size 14 tags were displaying on the service as measurements 20-22.
"If buyers measuring 20-22 acquire them they will likely be quite upset," she explained.
A different user, based in Derby, said she had been left angered due to the update requiring manual adjustment the sizing for "all her products".
"Personally, this is quite irritating, as I'm chronically ill and platform income has been essential following partial earnings loss," she said.
The platform boasts over 100 million users, with 18 million British users.
It has proved a popular alternative compared to resale services such as eBay and Depop.
This is not the initial instance where an unanticipated change on the platform has faced criticism: last year, the service retracted a modification to its shipping options after backlash from users.
A tech journalist and digital strategist with over a decade of experience covering emerging technologies and their impact on business and society.