Under Armour
Fly-By 3'' Running Shorts
£27
Product code: T128983S
About this style
Experience next-level comfort with these Fly-By 3'' running shorts from Under Armour. They're cut in a regular fit with split sides for unrestricted movement during your workout, whether you're hitting the gym, track, trail running, or going for a jog. The elasticated waistband features an internal drawcord for a secure, adjustable fit. Made from lightweight, breathable fabric, they wick away moisture and dry quickly to keep you feeling fresh during athletic training sessions, even when things get sweaty. Practical details include an invisible zip pocket for your valuables and mesh panels for enhanced ventilation, making them ideal performance activewear and sport apparel for any active pursuit. These comfortable athletic bottoms are perfect fitness gear for the dedicated athlete seeking new levels of comfort and functionality.
Details & care
Details & care
Fit and style
•
Regular fit
•
Elasticated waist
•
Mid rise
Composition
Body - 100% polyester
Care
Machine wash according to instructions on care label
Delivery, collection & returns
Delivery, collection & returns
Delivery
Standard
Free over £60, or £3.99
Returns
UK returns
Free. Returns can only be arranged via postal options. Exclusions apply Full delivery and collection information Our returns policy
Exclusions apply
Full delivery and collection informationOur returns policyAbout Under Armour
About Under Armour
Train at your best, no matter the weather, with Under Armour's innovative clothing, footwear and accessory designs.
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Reviews (116)
Absolute best workout shorts
Originally posted on Under Armour
Yes, I recommend this
I am in the gym 4 times a week and absolutely love these shorts! They’re so comfortable, great for sweating, and they look amazing on me!
Helpful?
Great fit and love the colorways
Originally posted on Under Armour
Yes, I recommend this
These are the perfect gym shorts with an assortment of colors that can go with any outfit. Price point is also spot on, making these an easy buy time and time again.
Helpful?
Excellent shorts
Originally posted on Under Armour
Yes, I recommend this
Very comfortable, size is correct. Bought size L.
Helpful?
So comfy
Originally posted on Under Armour
Yes, I recommend this
these are my new favorite shorts. very comfortable and the color is great
Helpful?
great fit, soft feel
Originally posted on Under Armour
Yes, I recommend this
A great fit, comfortable feel and easy dry short.
Helpful?
Great for around the house and the gym
Originally posted on Under Armour
Yes, I recommend this
The fly bys are perfect for the gym, running, and even casual athleisure wear. They’re lightweight, breathable, and move really well during workouts, whether it’s lifting or cardio. At the same time, they look good enough to wear outside the gym when running errands or just lounging. A versatile and comfortable option I keep reaching for.
Helpful?
Just wish they werent see through
Originally posted on Under Armour
No, I don't recommend this
Love the shorts, however, after trying them on, they are see-through. Not only can you see through the yellow fabric to the white liner you can also see-through the white liner and see your underwear.
Helpful?
Replied
09 September 2025
Hey, Michelle! Thanks for loving the shorts, but we hear you on the transparency. We're so sorry about that. We'd love to make this right! Look out for an email soon.
Very Comfy
Originally posted on Under Armour
Yes, I recommend this
Very comfortable shorts for cycling and great vibrant colour!
Helpful?
Great active wear
Originally posted on Under Armour
Yes, I recommend this
Love the fit and colour of these shorts . True to size and very comfortable !
Helpful?
Cute but transparent
Originally posted on Under Armour
No, I don't recommend this
I have these shorts in black and love them. Purchased a new pair in light blue and surprised to find they are see-through. You can see the white liner underneath and it looks like I’m running in my underwear. Such a shame because otherwise it would be perfect!
Helpful?
Replied
25 August 2025
Hi, Sarah! Oh, no! See-through shorts is definitely not the vibe we were going for and we're sorry that happened. We want you to feel comfortable and confident in our gear and it sounds like this wasn't it. Thanks for calling this out. Please look for an email from me on how we can make this right!
Minimal ride up
Originally posted on Under Armour
Yes, I recommend this
Love the inside layer and they really don’t move.
Helpful?
Love these shorts
Originally posted on Under Armour
Yes, I recommend this
I love these shorts. Perfect color blue, bright but also easy to pair with shirts. They are true to size.
Helpful?
Uncomfortable fit & lack of pockets
Originally posted on Under Armour
No, I don't recommend this
The quality was okay but the built-in underwear liner was not comfortable and did not allow me to pull the shorts up to the desired height. I cut out the underwear which made them far more comfortable and easier to move/workout in. However, upon wearing them, I notice the pockets that it was advertised to have were not there and the only “pocket” was a very small zip pocket that would only fit a few quarters or a small item. My credit card couldn’t even comfortably fit in the pocket let alone my phone, which rendered the shorts essentially useless. Unfortunately because I cut out the underwear, I can no longer return the product due to the missing pockets.
Helpful?
Replied
13 August 2025
Thanks for taking the time to share your experience with us! We’re sorry to hear the shorts didn’t meet your expectations for comfort and functionality — especially with the pocket situation. That’s definitely not the performance we aim for. We’ll be reaching out via email shortly to connect and see how we can help make this right for you.
Love them!
Originally posted on Under Armour
Yes, I recommend this
These are so light weight and fit perfect. The length is great usually I find this short style to fit shorter. Not these ones. Overall great quality and great fit! I ended up purchasing 4 more pairs.
Helpful?
Most comfortable shorts
Originally posted on Under Armour
Yes, I recommend this
Love the color and the fit
Helpful?
Comfortable shorts
Originally posted on Under Armour
Yes, I recommend this
These are very lightweight and breathe nicely while running. The small pocket fits keys or pepper spray.
Helpful?
Color: Horizon Blue-Horizon Blue (465)
Originally posted on Under Armour
Yes, I recommend this
Nice looking shorts. Like the loose fit BUT a little oversized. Recommend purchasing a size smaller.
Helpful?
Great for the gym
Originally posted on Under Armour
Yes, I recommend this
Comfortable and a good length (I'm 5'11), I would buy again
Helpful?
Very Dissapointed
Originally posted on Under Armour
No, I don't recommend this
Very disappointed I have wore under UA for years I have some shorts ten plus years old and never have I ever after wearing one time today for the first time the UA emblem came off. Not what I expected for the price and years I have had UA meet top expectations.
Helpful?
Replied
21 July 2025
Hi, Charity! Thanks so much for rocking with us through the years--we appreciate you! We're so sorry the logo came off and we totally understand the disappointment, as that should not have happened. Quality is the name of our game, so please look for an email from me on how we will make this right.
Great shorts!
Originally posted on Under Armour
Yes, I recommend this
They are so comfortable and cute!
Helpful?
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