Uniqlo Size Guide: What Size Am I in Uniqlo? Fit Advice & UK Sizing Help

Minimalist, affordable, and engineered for daily comfort—Uniqlo has become a staple in wardrobes across the UK and beyond. But whether you’re buying your first HeatTech layer or stocking up on Ultra Light Down jackets, one question is always on shoppers’ minds:

What size am I in Uniqlo—and does Uniqlo run big or small?

✨ Tellar.co.uk helps you find your correct size in thousands of brands, including Uniqlo. We’ll send you a free tape measure, you set up your profile once, and get instant size recommendations tailored to your body and each product’s cut. Always free. No guesswork. No returns.

In this guide, we’ll break down how Uniqlo sizing compares to UK high street sizing, what to watch for across categories, and how Tellar takes out the guesswork for you.

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About Uniqlo: Simple Clothing, Smart Design

From Tokyo to London, Uniqlo is known for:

• Technical fabrics like HeatTech™, AIRism™ and Ultra Light Down

• Affordable wardrobe essentials with premium feel

• Clean silhouettes, neutral colours, and quiet design

• Collaborations with brands like JW Anderson, MARNI, and Theory

But with roots in Japan, many shoppers find Uniqlo sizing feels smaller or shorter than UK equivalents, especially in tops, trousers and outerwear.

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Is Uniqlo True to Size?

Uniqlo runs small in some cuts, particularly in tops, trousers, and outerwear, while pieces like leggings, loungewear, and knitwear tend to fit more true to size. If you’re between sizes or curvier through the hip or bust, you may need to size up.

Fit Snapshot:

• HeatTech – slim and close to the skin

• Down jackets – run small, especially in arms

• Trousers & jeans – fitted at waist, straight in leg

• T-shirts & shirts – short in torso and sleeve

• Knitwear – more forgiving

📏 Check your Uniqlo size instantly using Tellar. It compares your shape to each garment’s structure—across men’s, women’s, and unisex fits.

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UK to Uniqlo Size Conversion

🎯 Create your Tellar profile to get exact Uniqlo size matches by garment type—based on bust, waist, hips, height and layering preferences.

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How Uniqlo Fits by Category

1. HeatTech Base Layers

Designed to sit close to the skin for thermal insulation.

• Fit: Very snug by design

• Size Tip: Stick with your size for warmth; size up for comfort

• Tellar Tip: Tellar calculates stretch, torso height and layering use

👕 Related: Berghaus Sizing Guide | Regatta Fit Help

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2. T-Shirts, Shirts & Blouses

AIRism™, Supima cotton, Oxford, or poplin—often minimal in structure.

• Fit: Fitted in shoulder, short in torso

• Size Tip: Size up for room in bust or if tall

• Tellar Tip: Shoulder width and torso length ensure better proportions

👚 Related: COS Sizing Guide | Reiss Fit Advice

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3. Trousers & Denim

Slim, straight or ankle-grazing cuts with structured waistband.

• Fit: True to size at waist, fitted through hip and thigh

• Size Tip: May need to size up if curvy

• Tellar Tip: Rise, hip and thigh shape used to avoid waistband tightness

👖 Related: Everlane Denim Sizing | Selected Femme Sizing Help

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4. Ultra Light Down & Padded Outerwear

Uniqlo’s most iconic jackets—designed to be light, warm and compact.

• Fit: Narrow in shoulder and sleeve

• Size Tip: Size up for layering

• Tellar Tip: Layering preference toggle adjusts down jacket sizing perfectly

🧥 Related: North Face Fit Guide | Patagonia Sizing Help

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5. Loungewear & Knitwear

AIRism™, fleece, fine merino and cotton knits.

• Fit: More generous and forgiving

• Size Tip: Stay true to size

• Tellar Tip: Tellar adjusts for desired fit—fitted vs oversized

🧶 Related: Ganni Fit Guide | Hush Size Advice

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Why Uniqlo Sizing Can Be Tricky

• Many garments are cut for Japanese proportions (shorter torsos, narrower shoulders)

• Product listings may lack garment measurements

• Some ranges are unisex, which changes sleeve or rise fit

• Fit varies between collaboration pieces vs core basics

That’s why Tellar.co.uk eliminates guesswork. It matches your shape to Uniqlo’s actual sizing—per product, fabric, and purpose.

🎁 You’ll also receive a free tape measure so you get it right from the start.

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Popular Uniqlo Pieces (and How They Fit)

⭐ Ultra Light Down Jacket

Packable and insulating

• Fit: Snug, especially at shoulder

• Tellar Tip: Shoulder and bust matched to layering habits

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⭐ AIRism T-Shirt

Soft-touch, breathable, anti-odour

• Fit: Fitted and short

• Tellar Tip: Height + torso length ensure better drape

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⭐ Smart Ankle Trousers

Tailored, cropped and structured

• Fit: Fitted at waist and hip

• Tellar Tip: Rise and thigh width calculated for mobility

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⭐ Merino Wool Crewneck Jumper

Lightweight, minimalist layering

• Fit: Relaxed and true to size

• Tellar Tip: Fit preference toggle adjusts sizing (relaxed vs fitted)

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Related Size Guides You Might Like

• Everlane Sizing Guide

• COS Fit Advice

• Toteme Sizing Guide

• Muji Fit Breakdown

• How to Measure for Unisex & Utility Clothing

Explore more via the Tellar Blog or use the Store Size Lookup Tool to check your Uniqlo size right now.

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Final Verdict: What Size Am I in Uniqlo?

You’ll often need to size up in structured tops, outerwear and trousers—especially if you’re tall or curvy. HeatTech fits tight by design, while knitwear and loungewear are more relaxed.

🎯 Let Tellar.co.uk match your body to your best Uniqlo size—and thousands of other brands—based on how clothes really fit.

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✅ Ready to Find Your Uniqlo Size?

• Create Your Free Tellar Profile

• Check Your Uniqlo Size Instantly

• Explore More Fit Guides

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