H&M is to bring its women's clothes sizes into line with the UK standard following complaints from customers.
The high street chain said it was changing its measurements after listening to "valuable feedback" from customers.
An H&M spokeswoman said: "Following customer feedback, we are taking the steps to change our womenswear measurements to be in line with UK sizing, for example the previous measurements and fit of a size 12 will now be the measurements of a size 10.
"Customers will experience a transition period and are encouraged to use our sizing guides online or ask our store staff for advice when shopping.
"We believe this transition will improve our overall customer experience and we hope our customers will feel encouraged we have listened to their valuable feedback."
Many shoppers have previously complained that H&M sizes are too small.
In March, shopper Rebecca Parker wrote an open letter after she struggled to fit into a size 14 at H&M despite being a 12 to 14.
She wrote: "The more I thought about it, and those jeans, I realised it wasn't my failure that prevented me from pulling on a pair of trousers, but yours.
"I am very proud of my body. It has taken a long time but I am thoroughly content with my large hips, squishy thighs and little tum, thank you very much.
"When I tried on your jeans I was annoyed, hot and frustrated. The pair of jeans clearly were not made for a woman who is a size 14. Why is that?"
The Swedish firm is the world's second-biggest clothes group after Zara owner Inditex.