What Is Sizing Like at Sundé? Does It Run True to Size?

SIZING GUIDES · LOUNGEWEAR & UNDERWEAR

By Ella Blake — Senior Fashion Stylist & Founder | TellarAlways honest, unbiased, & unsponsored

Sundé runs true to size across its loungewear and underwear collections — but with a few nuances worth knowing before you buy. I've been watching this brand quietly for a while, and the consistent customer feedback (combined with the stretchy, forgiving fabrications Sundé works with) confirms what I suspected: if you know your measurements, you're unlikely to be caught out. That said, there are a couple of garment categories where sizing up makes more sense, and I'll walk you through all of it here.

What Is Sundé?

For those who haven't come across it yet, Sundé (sundeapparel.com) is a UK-based premium loungewear and underwear brand with a very clear vision: incredibly soft fabrics, considered design, and a community-first ethos. Think buttery-soft sets, velour-touch leggings, ribbed bralettes, oversized fleece hoodies, and luxe sleep sets — all built around that "lazy Sunday at home but make it chic" feeling. It's indie in spirit but polished in execution, and the quality is genuinely impressive for the price point.

It started as a small-batch brand and has grown steadily through TikTok and Instagram word-of-mouth. If you've seen those gloriously soft co-ords all over your For You page, there's a decent chance it was Sundé. They size in XS through XL (and some pieces in S-XL), and the overall sizing philosophy is relaxed and inclusive.

Does Sundé Run True to Size?

Generally, yes. Across the core range — the tracksuits, hoodies, and sweatshirts — most customers report that Sundé fits as expected. The brand uses primarily soft jersey, velour, and fleece-style fabrics with good stretch recovery, which means even if you're between sizes, the fabric does a lot of the work for you.

That said, here's my honest breakdown by category:

Lounge sets and tracksuits: True to size. The relaxed-fit cuts mean even if you're a fuller size 12 or 14, a medium will likely work comfortably. If you prefer an oversized look — which, honestly, is how these are styled best — size up one.
Hoodies and fleece pieces: The oversized hoodies are designed to be roomy, so stick to your usual size unless you're very petite, in which case you might want to size down. I'm a 10 and I'd take a Small in most of the hoodies for a fitted-but-cosy result.
Leggings: True to size, with a high-waisted fit that's supportive without being restrictive. The velour-touch leggings in particular have a really flattering waistband. No gapping, no rolling — which is more than I can say for a lot of brands I've tested.
Bralettes and underwear: I'd suggest going true to size here based on your band size. The bralettes have a relaxed, non-wired fit so they're not built for heavy support — they're all about comfort and aesthetic. If you're a larger cup, size up for coverage.
Sleepwear: True to size or size up for a more relaxed bed-friendly feel. I always size up in pyjamas because I cannot bear anything even slightly snug when I'm trying to sleep — personal quirk, but worth mentioning!

Sundé's own size guide recommends measuring your bust, waist, and hips and comparing to their chart — and if you're between sizes, they suggest sizing up for a more relaxed fit. That's sensible advice for a brand built around comfort-first dressing.

Fit Tips for Different Body Types

One thing I genuinely appreciate about Sundé is that the relaxed silhouettes work across a wider range of bodies than more structured brands. You don't have to be a sample size for this to look good — the pieces are designed to drape and feel soft rather than cling and constrict.

Petite: Stick to your usual size or even size down in the oversized pieces if you don't want to be swamped. The leggings are fine at standard length for most petites (I've heard no major complaints on this front).
Fuller bust: Size up in bralettes — non-wired styles need more fabric to sit well at larger cup sizes. For sweatshirts and hoodies, your usual size should work fine as the cuts are generous through the chest.
Curvier through the hips: True to size is your best bet. The waistbands on the bottoms are stretchy, so they accommodate curves without digging in.
Tall: The leggings and joggers may sit slightly above the ankle if you're 5'9" or above — it's worth noting, though on cropped styles it works in your favour.

High Street Alternatives to Sundé

If Sundé isn't quite in budget right now, or you want to shop for similar vibes at different price points, here's where I'd point you:

HIGH STREET

M&S — Marks & Spencer's soft cotton and modal loungewear is genuinely brilliant. Their mix-and-match jersey sets are incredibly comfortable and their underwear sizing is accurate and consistent. A brilliant starting point.
The White Company — Their loungewear is on the pricier end of high street but the quality rivals Sundé. Super-soft jersey co-ords, beautiful sleep sets, and clean minimalist styling. Sizes very consistently true to size.
Cos — If you love that understated, quality-led aesthetic, COS does relaxed knit sets and soft loungewear that quietly nails the same energy. Their sizing runs slightly generous so go true to size.
Zara — Has upped its loungewear game considerably. Their ribbed sets and oversized hoodies are a genuine dupe for the Sundé aesthetic at a lower price point. Sizing can vary slightly so check reviews per piece.
H&M — The Move collection in particular is worth looking at for stretchy, soft co-ords. H&M sizing runs fairly true to size for their lounge range. Great for affordable layering pieces.
Lululemon — If the leggings are what you're after, Lululemon is the gold standard. Yes, it's a bigger investment, but the quality and sizing consistency is exceptional. True to size across the board.
Urban Outfitters — Brilliant for matching lounge sets with that same TikTok-friendly aesthetic. Their BDG and UO own-brand pieces offer the matching co-ord looks at more accessible prices.
Sweaty Betty — For anyone who wants the legging quality of Sundé but with more of an activewear edge. Excellent fit, true to size, and their Power Leggings are a classic for a reason.

PREMIUM

Lounge Underwear — The closest comparison to Sundé in terms of aesthetic and market position. Matching ribbed sets, soft co-ords, beautiful bralettes. Sizing runs true. If you want something very Sundé-adjacent this is the first place I'd look.
Skims — Kim Kardashian's brand has become a genuine powerhouse for underwear and soft loungewear. The fabrics are exceptional, and their sizing is helpfully detailed on the site. Worth the splurge if you want something truly buttery.
Mint Velvet — A step up in sophistication. Their loungewear and knit sets have a more grown-up, editorial feel while keeping the comfort-first ethos intact. Sizing runs true.

LUXURY

Eberjey — The ultimate in luxury sleepwear and loungewear. The Gisele pyjama set has a cult following for good reason — impossibly soft, beautifully cut, and worth every penny for a treat-yourself moment. True to size.
La Perla — For when you want loungewear that doubles as lingerie. Exquisite fabrics, flawless cut, and sizing that's precise to continental European standards. Check their size guide carefully as it runs slightly small against UK sizing.

INDEPENDENT & NICHE PICKS

Dora Larsen — A beautifully curated London-based brand doing colourful, innovative lingerie and soft separates. The fabrics are thoughtfully chosen and the brand has a real point of view. Sizing runs true to size with helpful fit notes on each product.
Stripe & Stare — A brilliant British indie brand making ridiculously comfortable underwear and pyjamas from sustainably sourced fabrics. Their sizing is very consistent, and the knicker and lounge sets have a loyal following for a reason. Truly one to bookmark.

Never Guess Your Size Again — Try Tellar

If you're shopping Sundé, Lounge Underwear, Skims, or any of the brands above and want to know your exact size before you buy, this is where Tellar.co.uk becomes your best friend.

Tellar is the UK's leading free sizing tool — measure once (bust, waist, hips or your size in an existing brand) and get your precise size across 1,500+ brands instantly. No charts, no guesswork, no returns.

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My Final Verdict on Sundé Sizing

Sundé is one of those brands where the sizing anxiety genuinely isn't necessary — the fabrics are forgiving, the cuts are relaxed, and the brand has clearly thought about fit for real bodies rather than just sample sizes. Go true to size across the loungewear and bottoms range, size up if you want that oversized loungewear look (and let's be honest, we all do), and size up in bralettes if you're a larger cup size.

It's an indie brand doing something genuinely lovely in a saturated market, and the quality really does back up the price tag. My only honest note: the range is still building, so if you want something very specific in terms of coverage or support, check each product individually rather than relying on a blanket size rule.

And as always — if you're in any doubt, pop your measurements into Tellar's Store Size Lookup tool before you order. It takes 30 seconds and saves a lot of faff.