Lowri Bryne, 22, shared photos of her struggle on H&M’s Facebook page which she described as “absolutely ridiculous”.
The student from Swansea is a size 12 and describes herself as “small busted”, but she was overcome with frustration when the size 16 dress she tried on didn’t fit.
She said: “Today in a H&M store I had to ask if this dress came in a size 18 (it didn’t…). The dress I have on in these photos is a size 16, and I could barely breathe.
“Not only was this annoying because I wanted to buy this dress, but so many women take what size dress they buy to heart. If I was one of these girls (thankful I’m not) requesting a size 18 dress would seriously devastate me!
“When I asked if this dress came in an 18 the store assistant said ‘ahh yeah you have to go up a couple of sizes with these’. A couple?!? Going up 3-4 sizes surely should make you realise that you need to seriously sort out sizing!!!’.
Lowri’s post has been liked by thousands of women and hundreds of comments from shoppers agree that sizes aren’t true to life.
One woman who replied to Lowri’s post saying she had experienced the same problem.
She said: “I also tried this dress on in H&M a few weeks ago in two sizes above my actual size and couldn’t even get the zip up!! Then I tried (and brought) another dress in the same size that I actually am and if fitted perfect!?”
Another said: “I’m a size 10 and have to buy 16/18’s in H&M!”
Express.co.uk has contacted H&M for comment.
Another clothes shopper had a sizing issue when she bought a pair of size 14 jeans which turned out to be bigger than a size 18 in another retail store.
Lucy Horsely from East Yorkshire posted a picture on Facebook of two different jeans she had purchased from River Island and New Look.
The first size was a size 18 from River Island, and the other a size 14 from New Look.
The larger of the two pairs, which on the label read size 18, turned out to be smaller than the…