Why Not Brand Sizing: Does It Run True to Size?

By Ella Blake — Fashion Stylist | Tellar Fashion Hub — Always honest, unbiased, & unsponsored

Why Not Brand runs small — as Italian sizing tends to — and you should, as a rule, size up at least one size from your usual UK size. The brand uses standard Italian numerical sizing (36–46), and if you're used to shopping British high street, those numbers will look unfamiliar at first. Don't panic. Once you know the conversion, it's actually pretty straightforward — and the clothes themselves are genuinely good.

I first came across Why Not Brand through a wholesale buyer I know — she'd discovered it at Centergross in Bologna and couldn't stop raving about the dresses. Founded in 2015 by two brothers from Naples, the brand started with a single showroom in Aversa and quickly expanded across Italy and into Europe. They now stock in over 250 Italian boutiques and 70 outlets across Europe, which tells you the product is resonating. The aesthetic is unapologetically feminine — think bold prints, stretchy ponte fabrics, bodycon silhouettes, and occasionwear with real personality. It sits in that sweet spot between high street and premium, which makes getting the sizing right absolutely essential before you buy.

Understanding Why Not Brand's Sizing System

Why Not Brand uses Italian sizing, which is a numerical system that runs approximately 2 sizes higher than the equivalent UK number. So an Italian 40 is broadly a UK 10, and a 44 is roughly a UK 14. However — and this is important — Italian brands are cut for a slimmer, more tailored silhouette than UK brands. The waist and hip proportions are generally narrower, and there's far less built-in ease. That's why, even once you've converted your size, you'll often find it pays to size up one further if you have a fuller bust, generous hips, or simply prefer a bit of comfort room.

The brand's garments are primarily made from stretchy knit fabrics and structured ponte, which does give a little more forgiveness than woven pieces. But don't rely on stretch alone — I've seen women get caught out assuming stretch means they can stick to their normal size, and then end up in something that's technically on but looks a size too small. On Italian stretch fabrics, size up. Always.

Why Not Brand: Size Conversion Table

IT SizeUK SizeUS SizeBust (cm)Waist (cm)Hips (cm)366280638738848466904010688709442128927498441410967810246161210082106

Use this as your starting point — always measure your bust, waist, and hips before ordering, and compare those measurements directly to the brand's size chart rather than relying on a label conversion alone.

Fit by Garment Type

Not all Why Not Brand pieces behave the same way, so it's worth knowing how sizing plays out across different categories:

Dresses: This is where Why Not Brand really shines — vibrant prints, body-skimming cuts, and stretch knit construction. That said, the dress silhouettes are designed for a slim Italian figure. If you're a UK 12 with fuller hips, you'll want to size to the hips (an IT 44) and accept that the waist may be slightly loose — easily nipped in with a belt. I wouldn't size down hoping stretch will save you. It won't.
Tops and blouses: The brand's tops tend to be fitted through the shoulders and bust. Shoulder width is the hardest thing to alter, so if you're between sizes, always size to the shoulder. A UK 12 will generally sit comfortably in an IT 42, but if you have broader shoulders, consider going to a 44.
Trousers and skirts: These tend to be the most challenging Italian pieces for UK shoppers. The waist measurement runs true to Italian standard, but the hip-to-waist ratio assumes more of a continental silhouette — which is often narrower through the hips relative to the waist. If you're apple-shaped, size to the waist. If you're pear-shaped, size to the hips and belt the waist.
Occasionwear and fitted blazers: For anything structured, I'd recommend measuring your bust carefully and going up one size from your standard conversion if you're in any doubt. You can always tailor in; you can't add fabric.

My Honest Take on the Brand

Why Not Brand is the kind of label that a certain type of Italian woman wears and looks absolutely sensational in — and then British shoppers see it online, order in their normal size, and wonder why it feels tight. It's not that the brand runs dramatically small compared to other Italian labels; it's that the cut is unapologetically Italian. Once you've cracked the sizing, though, there's genuine style here: the occasionwear prints are bold without being garish, the fabrications are far better than the price point suggests, and the silhouettes photograph beautifully.

If you're a UK 10–12 on the high street and you're ordering from Why Not Brand for the first time, I'd start with an IT 42 and treat it as your benchmark. If that fits well through the bust and shoulders, you've found your size.

High Street Brands to Shop for a Similar Vibe

If you love the feminine, print-led aesthetic of Why Not Brand but want more sizing certainty — or you're after the same energy at a more familiar fit — here's where I'd point you:

Zara — Comes closest to the Italian aesthetic at high street prices. Their occasion dresses and knit bodycon styles have a very similar energy to Why Not Brand, with Spanish/European sizing conventions that are broadly comparable. Size up one from your usual Zara size if you're between.
Mango — Another Iberian label with a sleek, continental cut. Their stretch midi dresses and fitted blazers are excellent alternatives. Generally runs slightly small, so size up if in doubt.
Massimo Dutti — For the more polished, tailored end of the Why Not Brand aesthetic. Quality fabrication, sophisticated prints, and European sizing. A great option when you want something that feels considered.
Phase Eight — One of the best UK high street options for occasion-forward dressing. Sizes in UK standard, runs true to size, and they understand how to cut for British body shapes. Particularly good for midi dresses and occasionwear.
Hobbs — More classic in its approach but with the same attention to fit and quality fabrication. Their occasion dresses are beautifully cut and run reliably true to UK sizing.
Reiss — Sits at the premium end of high street and delivers Why Not Brand's fitted, feminine silhouette in a UK-friendly cut. Their bodycon and shift dresses are consistently well-reviewed for fit.
Anthropologie — If you love bold prints and personality-led occasionwear, Anthropologie is your friend. More relaxed in its fit philosophy than Italian brands, and brilliant for floral and abstract prints.
Me&Em — For the elevated everyday version of this aesthetic. Brilliant tailoring, generous proportions that actually work for UK bodies, and a colour palette that's mature without being dowdy.
Coast — Underrated. Genuinely excellent for occasion dressing in UK sizing, with a similar feminine print language to Why Not Brand. Often on sale, which makes the quality feel like a steal.

Two Independent Labels Worth Knowing

Never Fully Dressed — A London-based independent label that does bold prints, wrap dresses, and stretch knit bodycon silhouettes in a way that's very much in the spirit of Why Not Brand — but with UK sizing and inclusive sizing that goes up to a size 26. Their print game is genuinely exceptional, and their wrap dresses in particular are a brilliant alternative. Find them at neverfullydressed.co.uk.

Aligne — A contemporary UK womenswear label with a European sensibility, particularly strong on structured occasionwear and feminine tailoring. They use the same kind of slim, figure-forward silhouettes as Italian brands but cut for UK bodies with realistic proportions. Consistently excellent quality for the price. Browse at aligne.co.uk.

Stop Guessing Your Size — Use Tellar

Navigating Italian sizing shouldn't be a guessing game. Tellar.co.uk is the UK's leading free sizing tool — match your exact measurements to 1,500+ brands instantly. No downloads. No subscription. Always free.

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Plus, the Tellar Fashion Hub is a growing library of honest, unsponsored style advice from our team of stylists. If you're trying to decode European sizing or build a wardrobe that actually fits, it's all there — free, unbiased, and independent.

→ Visit Tellar.co.uk → Store Size Lookup Tool