No, stick to your usual size for the Define Jacket; size up for broad shoulders or bust, or size down only if you want a compressive fit.
The Define Jacket is a slim-fit layer with stretch and shaping seams. That mix gives a close, sculpted look without feeling stiff. Most shoppers stay true to size. The right call comes down to how you like a jacket to feel through the chest, shoulders, midsection, and hips.
Size Up Or Down For The Define Jacket — When It Makes Sense
If you’re new to the brand, start with your regular top size from athletic wear. From there, adjust based on pressure points. The jacket should zip easily, sit flat at the chest, and allow full arm movement without pulling across the back. Sleeves should land at the wrist with room for the thumbholes.
Fast Fit Check: Zip, Reach, Breathe
Do a quick try-on routine: zip fully, raise both arms, then clasp your hands behind your head. You want smooth movement through the lats and upper back. If the zipper waves or the fabric tunnels at the midsection, the size is off. If the collar bites when you look down, try the next size.
Early Sizing Cheat Sheet
The jacket comes in multiple fabric lines (Luon, Nulu, cropped, hooded, and relaxed variants). All feel stretchy, but the drape and surface feel differ. Luon leans structured; Nulu feels lighter and softer. Fit logic stays the same: mild compression in your regular size, extra room one size up, and a sculpted look one size down.
Define Jacket Fit Cheatsheet
| Fit Concern | What You’ll Notice | Smart Size Move |
|---|---|---|
| Chest Or Bust Pressure | Puckering at zipper, pulling at armholes, hard to zip near bust | Go up one size |
| Shoulder/Back Tightness | Restricted reach, tight across lats when arms lift | Go up one size |
| Waist Or Midriff Bunching | Fabric tunnels or folds when zipped | Go down one size |
| Hip Tightness (Long Torso/Hip Curve) | Zipper waves over hips, hem rides up | Go up one size or try a relaxed cut |
| Sleeve Length | Thumbholes strain or sleeves sit short | Go up one size |
| Very Snug Look Wanted | Second-skin, sculpted profile | Go down one size |
How The Define Jacket Is Cut
The pattern is slim through the chest and waist with contouring seams and a hip-length finish. Stretch fibers help the fabric rebound after movement. The Nulu version trades structure for a softer hand-feel; the Luon version keeps a touch more body. You’ll still get four-way stretch either way. See the official product pages for fabric and features: Define Jacket Nulu and the classic Define Jacket Luon.
What “Slim Fit” Feels Like Here
In your standard size, the jacket hugs the chest and upper arms, tapers through the waist, and lands flat at the hem. It should feel snug yet easy to move in, not like a shapewear shell. If you hear stitches ping or feel the collar squeeze when you turn, that’s a red flag for a larger size.
Fabric Differences That Affect Fit
Luon gives a smooth face with a bit more structure, good for a crisp line. Nulu feels airy and buttery, great if you prefer a softer hand. Both include stretch fibers for movement and shape retention. If you’re between sizes and want a softer hug, Nulu often feels friendlier in your regular size.
Measure Once, Try Twice
Numbers help. Compare your chest and under-bust to the brand’s women’s tops chart. If your chest lands between two sizes, start with the lower size if you want a sculpted look and the higher size if you want easier layering. You can review the official women’s fit guide and size charts for chest ranges and conversions.
Chest, Back, And Shoulder Fit
The chest panel should sit smooth with the zipper line straight. If you see diagonal pull lines from the bust toward the armpit, go up. If the arm seam cuts in when you reach forward, go up. A slight hug at the upper back is normal; pinching is not.
Waist And Hip Fit
A gentle taper through the waist is part of the jacket’s shape. If the hem flips or the zipper bows across the hips, go up. If the midsection wrinkles in stacked folds, you likely have room to go down. For curvy hips, a relaxed-fit variant can solve hem lift without changing the top block fit.
Sleeve And Thumbhole Check
Sleeves should reach the wrist bone with the thumbholes lining up without strain. If the sleeve pulls when you use the thumbholes, go up. If the cuff drops past the palm, stay with your current size and skip the thumbholes or try a cropped cut to balance proportions.
Try-On Routine That Works
Use a simple, repeatable process at home or in-store. It takes two minutes and saves returns.
Step-By-Step Fit Test
- Zip to the top. The zipper should glide without forcing.
- Raise both arms overhead. Watch the side seams and shoulders for strain.
- Cross arms in front and behind. The back panel should move, not bite.
- Use the thumbholes. Cuffs should sit flat without tugging.
- Sit down. Check for hem creep or hip pressure.
- Layer a thin tee. If you plan to layer, repeat the moves with that base.
Fit Goals By Use Case
For light training or brisk walks, keep the close, true-to-size feel. For desk-to-studio wear, one size up creates easy movement over a tee or light long-sleeve. For a snapped, sculpted look in photos, a size down can work, provided the zipper sits flat and you can move without strain.
Common Body Shapes And Easy Tweaks
Everybody’s map is different. These quick tweaks help match shape to fit.
Bust-Forward Shapes
If the zip ripples at the top block, test one size up. Another route: pick a version with more give (Nulu) to keep shape without pressure.
Broad Shoulders Or Lats
Reach-forward tightness means the shoulder panel is short on ease. Try one size up. If the waist then feels loose, keep the larger size and use the sculpted seams to your advantage; the line still reads clean.
Curvy Hips
If the hem rides up, a larger size or a relaxed-fit spin solves the lift. A cropped version can also balance proportions while keeping the top block neat.
Straight Up-And-Down
If you miss a defined waist, the regular size gives shape without squeeze. If you want a sharper line, go down only if the zipper stays straight and movement stays free.
Variants That Change The Fit Feel
This jacket family spans several cuts. The feel shifts a bit by model, so match the variant to your fit goal.
Classic Luon
Slim profile with a touch more structure. True to size reads neat and polished. One size up turns it into a sleek layer over a tee without losing shape.
Nulu And Cropped
Softer hand, easy drape, and a lighter feel. True to size keeps a clean line; one size up creates a relaxed vibe while the seams still contour the torso. Cropped length helps if a full hem flips at the hips.
Hooded Or Relaxed-Fit Versions
Small design changes add room through the chest and back. If regular cuts feel snug, try these for a similar look with easier movement.
Size Ranges And Chest Landmarks
Use chest measurements to set a starting point. Then let the try-on routine confirm the call. The ranges below summarize common landings for women’s tops from the brand’s guide. For exact ranges and units, refer to the linked size chart above.
| Alpha/Numeric | Typical Chest Range | Starting Fit Tip |
|---|---|---|
| XS / 2–4 | ~30–32 in (76–81 cm) | True to size for a close line |
| S / 6 | ~33–34 in (84–86 cm) | True to size; go up for layering |
| M / 8–10 | ~35–36 in (89–91 cm) | True to size; up one for broad backs |
| L / 12 | ~37–38.5 in (94–98 cm) | True to size; down only for a sharp look |
| XL / 14 | ~40–42 in (102–107 cm) | True to size for comfort and shape |
| 1X–2X / 16–22 | ~45–51 in (114–130 cm) | Start true to size; up if shoulders feel tight |
Layering And Climate Tips
For cool gyms or air-conditioned offices, pick your regular size and add a thin long-sleeve base. Going outdoors in wind? A hooded or relaxed cut gives a touch more room for a thermal tee. If you need to stash a phone and cards, check pocket lay and bounce in a mirror walk test.
Care Moves That Protect Fit
Stretch fabrics last longer with gentle care. The brand recommends cold water, no fabric softener, and air dry. Those steps preserve stretch and surface feel. See the official guidance here: wash and care.
Return And Exchange Strategy
When you’re between two sizes, order both. Try them back-to-back with the same base layer and repeat the reach tests. Keep the one that zips smooth, moves clean, and sits flat at the hem. Send the other back right away so your closet stays lean.
Quick Answers To Common Fit Dilemmas
“I’m Between Sizes In The Chest.”
Pick the larger one if you plan to zip fully. Pick the smaller one only if you’ll wear it open most of the time and movement stays free.
“The Zipper Waves Near My Hips.”
That’s hem tension. Try one size up or a cropped or relaxed cut.
“Sleeves Pull When I Use The Thumbholes.”
You need more reach. Go up one size or switch to a variant with more room through the shoulder.
The Bottom Line
Start with your regular top size. Go up if you feel chest, shoulder, or hip squeeze, or if you want easy layering over a tee. Go down only if you want a sculpted line and the zipper still sits straight. The try-on routine tells the truth in minutes, and the official size chart links above back up the numbers.