You can wear seamless briefs, boyshorts, a thong, or nothing at all under leggings, and all four are normal. The right answer depends on what you are doing and whether the leggings have a lined gusset. For training, seamless or nothing. For everyday wear, whatever is comfortable. The only options that consistently cause problems are lace edges, thick waistbands and anything with seams crossing the front.
This covers every option and what each one actually does, how to tell whether your leggings are built to be worn without underwear, why visible lines happen and how to stop them, and what changes depending on the session.
The options, side by side
| Option | Best for | Watch out for |
|---|---|---|
| Seamless briefs | Most situations. The safest default | Check the leg opening lies flat rather than cutting in |
| Boyshorts | Longer sessions, extra coverage, reducing inner thigh friction | A thick hem can still print through thin leggings |
| Wide-front thong | Light or pale leggings where any leg line would show | A narrow front panel does nothing to smooth the shape |
| Nothing | Training in leggings with a lined gusset | Only works if the gusset is lined. Wash after every wear |
| Period underwear | Training on your period, no change to anything else | Choose a seamless style so the edge does not print |
| Fitted shorts over the top | Pale or thin leggings, extra coverage, reads as deliberate | Needs to be long enough not to ride up |
| Lace or decorative underwear | Not under leggings | The pattern prints through almost every fabric weight |
| Cotton briefs with a thick waistband | Everyday, under loose clothing | The waistband creates a ridge and holds sweat |
First: do your leggings have a lined gusset?
This decides whether going without is an option or a compromise, so it is worth checking before anything else.
A gusset is a separate diamond or triangle panel sewn into the crotch instead of a single seam crossing it. A lined gusset has a second layer of softer fabric on the inside, and that lining exists specifically so the garment can be worn against bare skin.
Turn the pair inside out and look:
- One seam running front to back, no panel. No gusset. Wear something underneath.
- A separate panel with its own stitching all the way around. Gusseted, single layer. Your choice.
- A separate panel with a second, softer layer inside it. Lined gusset. Designed to be worn without underwear.
The gusset matters for more than this. It is also the feature that prevents camel toe, which our guide to avoiding camel toe in leggings goes into properly.
Can you go commando in leggings?
Yes, and plenty of people do, particularly for training. It removes the only two things that create a visible line, and for anyone who finds a waistband-under-a-waistband uncomfortable it is the obvious answer.
Three conditions, though.
The leggings need a lined gusset. Without that lining you have a seam against bare skin, which is a friction point over a long session.
They need washing after every single wear. Not a second outing. Activewear worn against bare skin holds sweat and bacteria, and a second wear is where both odour and irritation start.
Get out of them when you finish. Sitting in damp compression fabric for hours afterwards is the part that causes problems, not the training itself.
If the pair has an unlined single seam through the crotch, wear something underneath. It is not a rule about modesty, it is about what the garment was built for.
Why visible lines happen
Visible panty lines do not come from underwear. They come from edges.
Any raised edge sitting under close-fitting fabric creates a ridge, and the legging fabric pulls across that ridge rather than over it. Your eye reads the resulting line clearly, particularly on pale or thin fabric where there is less to hide it.
So the question is never "briefs or thong". It is what the edge of the garment looks like.
| Edge type | How it behaves |
|---|---|
| Laser-cut or bonded | No stitching, no raised hem. Effectively invisible under leggings |
| Flat-locked seam | Low profile. Shows only under very thin or pale fabric |
| Stitched hem | Creates a defined ridge. The most common cause of a visible line |
| Elasticated band at the leg | Compresses the skin, so the line shows even through thicker fabric |
| Lace or picot trim | Prints the pattern itself through the fabric |
Four things that remove the line
- Choose laser-cut or bonded edges. They are designed for exactly this and nothing else performs as well.
- Match the tone to your skin, not to the leggings. Under light or pale fabric a skin tone effectively disappears where black shows through clearly.
- Size up in the underwear if the elastic is digging. Compression at the edge is what creates the ridge. A looser leg opening lies flatter.
- Check it standing still first. If the leg opening cuts in while you are standing, it will definitely show once you move.
The leggings matter more than the underwear
Three things about the leggings change the answer entirely.
Fabric weight. A thin knit shows everything. Hold a pair up to the light: if you can read print through it, assume anything underneath will be visible, and assume the pair will also go sheer in a squat.
Colour. Black and darker tones hide almost everything, including edges and seams. Light, pale and shiny fabrics show all of it, and pale fabric goes translucent when it is wet as well.
Whether there is a lining. Covered above, and it is the one that decides whether you need underwear at all.
You can see the current fabric and fit in the Freedom Cross Leggings and Freedom Staple Leggings, or browse bottoms.
Fabric: what sits against your skin for an hour
Underwear under leggings is in a difficult spot. It is against the skin, under a compression layer that does not breathe much, for the length of a session.
Moisture-wicking technical fabric moves sweat away from the skin, which is what you want for anything high intensity or long.
Cotton absorbs moisture and holds it. Comfortable to start, damp by the end. Fine for everyday wear, not ideal for training.
Anything non-breathable, including a lot of shiny synthetics, holds moisture against the skin without moving it, which is the exact condition irritation and chafing need.
Whatever you choose, change out of it when you finish rather than staying in it for the rest of the day. That single habit prevents most of the problems people blame on the underwear itself.
What changes with the activity
Reformer and pilates. The hardest case, because you spend time inverted with your legs in view. Seamless or nothing, full-length leggings, denser knit. Nothing you have to adjust mid-exercise.
Weights and gym floor. Deep squats put maximum tension through the crotch and seat. Seamless briefs or nothing, and a pair you have squat-tested in a mirror.
Running. Longer distance means friction matters more than lines. Boyshorts or fitted shorts reduce inner thigh contact, and our guide to preventing thigh chafing covers the rest.
Everyday and travel. Comfort wins. Whatever you normally wear is fine, with one caveat: a thick waistband sitting under the legging waistband creates a ridge and gets uncomfortable on a long flight.
Training on your period. Period underwear under your normal leggings works without changing anything else. Our guide to what to wear training on your period goes through it.
Layering shorts over leggings
Worth its own mention, because it is the one option that solves everything at once and reads as a styling choice rather than a fix.
Fitted shorts over leggings give you an extra layer exactly where opacity and lines are a problem, remove inner thigh friction, and work on pale or thin leggings where nothing else quite does.
The only requirement is length. They need to sit below the widest part of your thigh and stay there when you move, otherwise they ride up and you have added a problem rather than solved one.
Our Freedom Core Seamless Shorts are built without an inner leg seam for this reason.
What not to wear under leggings
- Lace or anything with a decorative trim. The pattern prints through almost every fabric weight.
- Decorative seams across the front. Any seam crossing the front creates a line in the one place it is most visible.
- A thick waistband that sits under the legging waistband. Two bands stacked creates a ridge and gets uncomfortable fast.
- Anything a size too small. Tight elastic compresses the skin, and that compression line shows even through thicker fabric.
- Yesterday's pair. Obvious, but worth saying for anything you are training in.
Hygiene, briefly
Leggings worn for training need washing after every wear, whether or not you wore underwear. Worn against the skin under compression, they hold sweat, body oil and bacteria, and a second wear is where odour becomes permanent in the fabric rather than something a wash removes.
Cold wash, inside out, no fabric softener. Softener coats the fibres, traps the oil and stops technical fabric wicking properly.
If you are unsure whether a pair fits properly in the first place, our guide to how activewear should fit covers the squat test.
Frequently asked questions
What underwear should you wear under leggings?
Seamless briefs are the safest default. They have no stitched edge to print through and they lie flat under close-fitting fabric. Boyshorts work for longer sessions, and a wide-front thong works under pale leggings where any leg line would show.
Are you supposed to go commando in leggings?
You can, and many people do for training. Most technical leggings have a lined gusset built for it. Check that the lining is there, wash the leggings after every wear, and change out of them when you finish.
How do I know if my leggings have a lined gusset?
Turn them inside out and look at the crotch. A separate diamond or triangle panel with a second, softer layer inside it is a lined gusset. A single seam running front to back means no gusset at all.
What underwear has no visible line under leggings?
Laser-cut or bonded-edge styles. They have no stitched hem, so there is no raised edge for the fabric to pull across. Matching the tone to your skin rather than the leggings also makes a visible difference under light fabrics.
Should you wear a thong under leggings?
It works well for avoiding leg lines, particularly under pale or thin fabric. Choose one with a wider front panel, because a narrow one does nothing to smooth the shape at the front.
Is cotton underwear bad under leggings?
Not bad, but cotton holds moisture rather than moving it, so it stays damp through a session. For training, a moisture-wicking fabric is more comfortable. For everyday wear it makes little difference.
Why do my underwear lines show through my leggings?
Almost always the edge rather than the underwear itself. A stitched hem or tight elastic creates a ridge that the legging fabric pulls across. Thin or light-coloured leggings make the same ridge far more visible.
Do you need to wash leggings after every wear?
Yes, particularly if you train in them or wear them without underwear. Activewear worn against the skin holds sweat, oil and bacteria, and a second wear is where odour problems start.
What should you not wear under leggings?
Lace, anything with decorative seams across the front, and briefs with a thick waistband that sits under the legging waistband. All three print through almost every fabric weight.
Can you wear shorts over leggings?
Yes, and it is the one option that solves opacity, lines and inner thigh friction at the same time. Choose a length that sits below the widest part of your thigh so they do not ride up.
The short version
Seamless briefs for most situations, a wide-front thong under pale leggings, boyshorts for longer sessions, and nothing at all if your leggings have a lined gusset. It is edges that show, not underwear, so choose laser-cut or bonded hems and match the tone to your skin rather than the fabric. Avoid lace and thick waistbands, and wash after every wear.
