An unhappy shopper has hit out at clothes store H&M over its sizing after she tried and failed to squeeze into a pair of its jeans.

In a Facebook post shared more than 10,000 times and commented on nearly 8,000 times, Ruth Clemens complained her experience “did not go well” even through the trousers should have fitted her.

A photo shows the size 16 jeans were significantly too small for her body, which she said usually suits size 14 trousers and medium tops.

Calling out the high street fashion giant for its "unrealistically small" sizing, the 25-year-old student wrote: "I'm normally a size 14 on my hips (occasionally 16 if buying trousers) so I thought I'd try them on. It did not go well.

"I am not overweight (not that that should matter) and although I'm 5 foot 11 my body is pretty average shape-wise. It's already difficult enough for me to find clothes that fit well because of my height, why are you making jeans that are unrealistically small?

"Am I too fat for your everyday range? Should I just accept that accessible and affordable high street and on-trend fashion isn't for people like me?"

She added: "You might recognise the top I'm wearing - it's one of yours and it's a size medium. Sort it out would you."

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A small selection of the comments in response to Ms Clemens' post

In a reply to Ms Clemens, H&M wrote: "We are sorry to hear about your experience in store recently. We always want our customers to have an enjoyable time when shopping in store and to leave feeling confident in themselves.

"At H&M we make clothing for all our stores around the world, so the sizing can vary depending on the style, cut and fabric. We value all feedback and will take on board the points you and other customers have raised."

An H&M spokeswoman said: "H&M works with the same measurements and sizes within all concepts, across all 62 markets and online; however, the fit of a garment may vary depending on the style, cut and fabric."

Ms Clemens' experience follows numerous debates on social websites such as Mumsnet about H&M's sizing.

In its online guide, H&M advises that a medium equates to a UK size 14-16 for a waist measuring from 29 inches, while large equates to a UK 18-20 or a waist measuring from 32 inches.

Marks and Spencer advises that its size 14 is for waists measuring 31 and three quarters inches, a size 16 is for 34 inch waists and a size 18 fits a 36 and three quarters waist.

Have you had similar problems with sizing in H&M or other clothes stores? Should stores all use the same sizing or would it better to drop the numerical system altogether? Add your comments below and vote in our poll.