Built for performance, recovery and everyday training, Under Armour is trusted by athletes, fitness fans and casual wearers around the world. With compression leggings, technical tops and high-support sports bras, the brand has become a staple in UK gyms, running trails and streetwear wardrobes alike.
But if you’re shopping online, one key question stands out:
What size am I in Under Armour—and does it run big or small?
✨ Tellar.co.uk helps you find your perfect size in thousands of brands, including Under Armour. You’ll get a free tape measure, set up your profile once, and get instant sizing recommendations based on real garment fit—across leggings, trainers, bras and more. It’s always free.
About Under Armour: Performance Meets Precision
Founded in the US in 1996, Under Armour specialises in:
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Moisture-wicking, heat-adaptive fabrics
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Compression and fitted base layers
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High-impact sports bras and leggings
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Trainers, hoodies, joggers and tactical outerwear
From cold-weather running gear to summer shorts and everyday gym kit, sizing can vary depending on compression level, fit intent (loose/fitted/compression), and regional sizing differences.
Is Under Armour True to Size?
Under Armour generally runs true to size, but it depends on the product’s fit category:
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Compression – designed to be skin-tight
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Fitted – close to the body but not restrictive
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Loose – roomy and relaxed
Compression gear and sports bras may feel tight or small for first-time wearers, while tops and jackets in the “Loose” fit category often run roomy.
📏 Use Tellar’s Store Size Lookup to check your Under Armour size instantly—based on your actual measurements and the specific garment cut.
UK to Under Armour Size Comparison
| UK Size | US Size (Women) | Fit Notes |
|---|---|---|
| UK 6 | XS | Snug in compression gear |
| UK 8 | S | True to size in most fits |
| UK 10 | M | Comfortable in fitted styles |
| UK 12 | L | Compression may feel tight |
| UK 14 | XL | Loose fits feel roomy |
| UK 16 | XXL | True to size or generous |
| UK 18–20 | 1X–2X | Available in selected categories |
🎯 Create your Tellar profile for personalised Under Armour sizing based on your chest, waist, hips, height and fit preference (compression vs relaxed).
Under Armour Fit Categories Explained
Compression
Engineered for muscle recovery and blood flow support.
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Fit: Very tight, second-skin feel
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Tip: True to size by design—don’t size up unless you prefer less compression
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Tellar Tip: Tellar adjusts sizing based on activity, body type, and comfort level
Fitted
Close to the body, but not restrictive.
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Fit: True to size
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Tip: Stay with your standard size for training
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Tellar Tip: Shoulder width and torso length determine comfort
Loose
Relaxed through the body for mobility and airflow.
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Fit: Oversized or boxy by design
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Tip: True to size unless you want a slimmer silhouette
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Tellar Tip: Toggle “relaxed” or “fitted” in your Tellar profile for better matches
How Under Armour Fits by Category
1. Leggings & Tights (HeatGear, Rush, Meridian)
Training, running, and recovery leggings with varying support.
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Fit: True to size in most styles; compression styles feel tight
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Tip: Stay true to size unless between sizes—then use Tellar
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Tellar Tip: Tellar matches waist, hip and rise to each fabric blend
2. Tops, Tanks & T-Shirts
Offered in loose, fitted and compression styles.
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Fit: Loose is roomy; fitted is standard; compression is tight
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Tip: Choose based on intended activity
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Tellar Tip: Tellar uses bust and shoulder width + length preference for each cut
3. Sports Bras (Infinity, Crossback, Armour Mid)
Designed by impact level: low (yoga) to high (running).
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Fit: Often tight in high-impact categories
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Tip: Size up in high-support styles if fuller-busted
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Tellar Tip: Tellar calculates bust and underband width to recommend proper support
4. Outerwear (Storm Jackets, Hoodies, Baselayers)
Wind-resistant, water-repellent and thermal-ready.
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Fit: Fitted or relaxed depending on use
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Tip: True to size unless heavy layering
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Tellar Tip: Use Tellar’s layering option to optimise fit for coats and base shells
5. Trainers (HOVR, Charged, SlipSpeed)
Performance footwear for gym, run or recovery.
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Fit: True to size in most models
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Tip: Size up half if between sizes or wider feet
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Tellar Tip: Tellar uses UK sizing, foot width and intended activity for shoe fit
Why Under Armour Sizing Can Be Confusing
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Compression fit is meant to feel snug—but not everyone expects that
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Online listings rarely explain fit category (compression vs loose) clearly
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Sizes may appear consistent, but impact level and fabric weight affect feel
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Trainers follow US sizing, and shoe fit varies by model
That’s why Tellar.co.uk removes the doubt. We use your body shape, comfort preferences and real garment data to recommend the exact right size every time.
🎁 You’ll also receive a free tape measure so your Tellar profile is precise—once and for life.
Popular Under Armour Styles (and How They Fit)
⭐ HeatGear® Armour Leggings
Compression-fit, sweat-wicking performance fabric
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Fit: Tight but supportive
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Tellar Tip: Tellar adjusts compression fit based on your workout intent and waist-to-thigh ratio
⭐ Infinity High Sports Bra
High-support bra for cardio and HIIT
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Fit: Structured and secure
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Tellar Tip: Bust and ribcage width determine perfect support match
⭐ UA Storm Jacket
Water-resistant running jacket
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Fit: Slimline but easy to layer
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Tellar Tip: Chest + layering preference used for outerwear accuracy
⭐ Charged Assert 9 Trainers
Everyday running shoes with firm midsole
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Fit: True to size
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Tellar Tip: Tellar factors foot width + arch height for trainer fit confidence
Related Size Guides from Tellar
Explore the Tellar Blog or check your Under Armour size instantly via the Store Lookup Tool.
Final Verdict: What Size Am I in Under Armour?
Most customers will wear their usual UK size, but fit varies by compression level, fabric and intended activity. Don’t rely on instinct—use Tellar.co.uk for real-time, body-specific sizing.
🎯 Whether you’re strength training or running a half-marathon—Tellar.co.uk ensures your Under Armour kit fits like it was made for you.
✅ Ready to Find Your Under Armour Size?
Find your size in thousands of brands real-time. It’s free & easy.
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