Mum horrified to find dress she ordered online fits her 4-year-old

We've all had one or two dodgy online shopping experiences, but one UK mum was left appalled when an outfit she ordered barely fit her four-year-old.

Kirsty Dee had ordered a $19 little black dress from online retailer PrettyLittleThing, a popular UK fast fashion site, to wear to a friend's birthday the next day.

But when the outfit arrived, Kirsty was horrified to discover that the size 8 t-shirt dress was less than half the size she expected.

She called out the brand, via Twitter, for the outrageous sizing writing: "So I bought this in a size 8 from @OfficialPLT [and it] wouldn't even go over my head."

In fact the dress was so tiny that it barely even fit her four-year-old daughter Molly, Kirsty sharing a snap of the little girl modelling the miniscule outfit.

"It just fits my 4 year old daughter! Really?????" Kirsty tweeted alongside the photo.

Speaking with The Sun, the UK mum explained that she was left without a dress for the event and was frustrated by the mistake.

"I just think it's disgusting how they promote body confidence and then send me a dress not fit for a size 6 – 8," she said.

Though she saw the funny side when she got little Molly in the outfit, admitting that she was able to laugh it off.

After sharing her tweets, PrettyLittleThing responded to Kirsty's comments and admitted something had gone wrong.

"So sorry to see that there is an issue with the dress you bought," they wrote, advising her to get in contact with her order number so that they could resolve the issue.

It's not the first time the fast fashion brand have had trouble with their orders, with several other women having complained about the retailer's sizing issues.

Just last week a woman ordered a size 8 dress that barely fit over one leg, while another woman a few years back ordered pants that were so long when they arrived they could have covered her from ankle to shoulder.