How to Find Your Size in ASOS When There Are So Many Different Brands

Finding your size in ASOS depends entirely on whether you're shopping ASOS's own label or one of the hundreds of third-party brands they stock — and the two can vary by a full size or more, which is exactly why so many of us end up drowning in returns. I've been there. I once ordered the same size in three different ASOS brands and none of them fit the same way. Here's how to actually crack it.

The Two Very Different Worlds of ASOS Sizing

The first thing to get your head around is that ASOS is essentially two things in one: their own in-house label (ASOS Design, ASOS Curve, ASOS Petite, ASOS Tall) and a marketplace for hundreds of independent and designer brands. These operate on completely different size charts, and mixing them up is where most sizing frustration comes from.

ASOS Design (own label) — generally runs true to size but can be slightly generous in jersey and relaxed styles. Their size guide is relatively consistent across their own garments.
Third-party brands — each one follows its own sizing logic. A size 12 in French Connection on ASOS is not the same as a size 12 in Reclaimed Vintage. Always check that specific brand's size guide, not ASOS's general one.

This sounds obvious when you put it like that, but ASOS doesn't always make it easy to spot which brands are own-label and which aren't — especially when you're scrolling fast. Always look at the brand name at the top of the product page before you trust any size recommendation.

ASOS Own-Label Size Conversion Table

For ASOS Design and their own-label ranges, this is a reliable starting point. Their sizing broadly aligns with UK standard sizing, though structured pieces (blazers, trousers) can come up slightly larger through the hip and waist.

UK SizeEU SizeUS SizeBust (inches)Waist (inches)Hip (inches)432030–3123–2433–34634232–3325–2635–36836434–3527–2837–381038636–3729–3039–401240838–3931–3241–4214421040–4133–3443–4416441242–4335–3645–4618461444–4537–3847–4820481646–4739–4049–50

Garment-by-Garment: What You Actually Need to Know

Even within ASOS Design, different garment types behave differently. Here's my honest take on each:

Dresses & jersey tops — Generally true to size. If you're between sizes, go with your usual. The stretch fabrics in their jersey pieces are quite forgiving.
Blazers & structured jackets — These can run a touch large through the shoulder, so sizing down is worth considering if you prefer a sharp, fitted look. I sized down in a blazer once on a whim and it was the best fitting one I owned.
Trousers & jeans (own label) — These can be generous on the waist but narrower through the thigh in slim cuts. Check if it says "relaxed" or "slim" fit — they're genuinely different. Measure your waist and hip before ordering.
Knitwear — Sizing varies wildly depending on the fabric. A fine-knit might come up smaller than expected; an oversized style will obviously sit large. Read the product description closely — ASOS usually specifies the model's height and which size they're wearing, which I find more useful than the size guide itself.
Coats & outerwear — True to size or size up by one to allow for layering. I always go up in coats.
Swimwear & lingerie — Their lingerie sizing is generally consistent with UK bra sizing. Swimwear varies more — check the specific brand, and if in doubt, order two sizes.

The ASOS Review Section Is Your Secret Weapon

Honestly? The single most useful tool ASOS gives you isn't their size guide — it's the customer reviews. Filter by your size and read what people with your measurements are saying. Comments like "came up small through the hips" or "length is much longer than expected" are pure gold and have saved me from more returns than I can count. It takes an extra two minutes and it's absolutely worth it.

Also look at the model dimensions listed under the product. ASOS are generally good at telling you the model's height and the size pictured, which helps enormously if you know your own measurements.

If ASOS Sizing Feels Like Too Much Guesswork…

I completely understand the appeal of shops where sizing is more consistent and you don't need to second-guess yourself every time. Here are my recommendations by category:

High street — reliable and size-consistent:

Cos — Minimal, Scandinavian-influenced pieces in a very consistent size range. If you know your Cos size, you know it for life. Their tailoring is especially reliable.
Mango — Excellent for current trends with sizing that stays broadly true across their ranges. Strong on tailored pieces and knitwear.
Whistles — A brilliant mid-market option that sizes consistently. Their workwear and smart-casual pieces are particularly well cut.
Reiss — Sits at the premium high-street end but their sizing is notably consistent season to season. Perfect for occasion wear where you can't afford a guess.
Me&Em — One of the most size-consistent British brands out there. Their fit guides are excellent, and the quality justifies the price point. A great ASOS alternative if you want a brand you can trust every time.
Phase Eight — Reliable, elegant sizing across occasionwear and separates. Particularly good for dresses if you find ASOS too inconsistent for events.
Hobbs — Classic, well-structured pieces with very predictable sizing. Once you know your Hobbs size, it sticks across almost everything they make.
Anthropologie — A broader style range than you might expect, with detailed size guides and customer reviews that rival ASOS's own. Their dresses and blouses are a consistent strength.

Premium picks:

Massimo Dutti — Quietly one of the best-kept secrets on the high street. Sizing is European but their own size guide is accurate and their tailoring is impeccable.
LK Bennett — A mainstay for occasion dressing with sizing that doesn't play games. Smart, classic and you'll know your size from the first purchase.

Independent & left-field picks:

Albaray — A quietly brilliant sustainable British brand with a tight, well-edited range. Their size guides are detailed and their fit is consistently excellent. Worth bookmarking.
Beaumont Organic — Ethical, beautifully made basics and elevated separates from a UK independent. Sizing is clear, true to size, and they're refreshingly transparent about their fabrics and production.

Stop Guessing Your Size — Use Tellar

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