But as one unlucky customer recently discovered, it doesnâ€™t always go according to plan.
Julia Magowan ordered the Â£18 Black Mesh Ruched Bodycon Dress from Pretty Little Thing in her usual size 8. But when the item arrived it, didnâ€™t quite fit.
In fact, the 21-year-old was shocked to discover that the dress didnâ€™t even pull up to her thighs, as she only managed to squeeze one leg in.
She took to Twitter to call out the fashion giant, writing: â€œPLT how do you expect me to fit my body into this supposed size 8 dress? Can just about fit my left leg in it, what a jokeâ€
plt how do you expect me to fit my body into this supposed size 8 dress?? Can just about fit my left leg in it, what a joke pic.twitter.com/knqtvK2PoG
â€” julia magowan (@_JuliaMagowan) March 12, 2019
â€œUpdate: fits nicely around my leg,â€ she joked, alongside an image of the number pulled over her left leg.
According to the website, the dress is a â€œweekend-worthy lookâ€ and is the perfect ensemble when styled with barely-there heels.
But itâ€™s not the first time high street sizes have been called into question by disappointed shoppers.
Back in June 2018, H&M finally pledged to make its UK sizes bigger after years of complaints.
Customer Rebecca Parker famously penned a candid letter to the company viaÂ FacebookÂ after struggling to fit into a pair of size 14 jeans â€“ despite being a size 12/14.
She wrote that although at age 25 she finally felt comfortable with her body, she worries about the damaging impact the brandâ€™s sizing could have on teenagers.
â€œMy thirteen-year-old self wasnâ€™t comfortable with being curvy. I felt fat, podgy and sad when I had to reach for a garment that was labelled with a number in the high teens,â€ she wrote. â€œWhy is it OK for a brand to label an item of clothing as a size which it clearly isnâ€™t?â€
After the backlash, it was revealed that the reason why so many of us end up buying larger-than-usual sizes at the high street chain is due to the way in which UK sizing matches up to its European equivalent.
In the UK, a size 10 correlates to a European size 38 but in H&M, size conversion means that clothes in this size were wrongly labelled as an EU 36 (which is a UK size 8).
Now, the Swedish chain is slowly rolling out more accurate sizes.