How Should a Rashguard Fit? BJJ & MMA Size Guide

A rashguard should fit like a second skin. Snug across the chest, no loose fabric to grab, and no riding up when you get stacked. This rashguard size guide shows you how to measure yourself, how to read a chart, and what to do when you sit between two sizes.

Short answer: A good rashguard is tight but not restrictive. It hugs your chest and arms with no bagginess. It stays tucked when you bridge or invert, and still lets you breathe fully. Measure your chest at its widest point, match it to the chart, and size up only if you're between sizes or want a bit less compression.

How a rashguard should fit on the mats

Think compression top, not gym tee. A rashguard is built to move with you, so it fits closer than anything else in your training bag.

Here's what a good fit looks like:

• Chest and back: snug all around, with no flapping fabric your partner can grab.
• Waist: long enough to stay tucked into your shorts or spats when you're upside down.
• Shoulders: you can lift your arms overhead without the hem jumping up.
• Sleeves: they stay put when you frame or shoot, and they don't cut into your biceps.
• Breathing: you can take a full, deep breath without feeling squeezed.

If you see wrinkles across your stomach or spare fabric under the arms, it's too big. If seams dig in or you feel short of breath after a few rounds, it's too small.

Why fit matters for BJJ and MMA

Fit isn't only about looking sharp. A loose top hands your partner free grips, which is not the deal in no-gi. It also bunches up under your back when you play guard. That's annoying for you and a bit gross for everyone else.

A rashguard that fits well actually does its job. It keeps a layer between your skin and the mat and cuts down on mat burn. It can't do much of that while it's flapping around your belly button.

How to measure yourself for a rashguard

Grab a soft tape measure and, if you can, a training partner. Wear a thin T-shirt or nothing at all, and stand relaxed with your arms by your sides.

1. Chest: wrap the tape around the fullest part of your chest, under the armpits and across the shoulder blades. Keep it level and snug, not tight.
2. Waist: measure around your natural waist, usually just above the belly button.
3. Back length (optional): measure from the base of your neck down to where you want the hem to sit.
4. Arm length (optional, for long sleeves): measure from the top of your shoulder down to your wrist.

Write the numbers down in centimeters. Chest matters most, so if you only take one measurement, make it that one. Any rashguard size guide is only as good as the tape measure you use with it.

Rashguard size guide: men's chart in cm

Here's the chart for Tribe Alpha short sleeve and long sleeve rashguards. All numbers are in centimeters, and they can vary by about 5% because every piece is made to order.

Size	Chest	Waist	Back length	Short sleeve	Long sleeve
XS	85	73	62	29.5	70.5
S	91	79	63.5	31	72.5
M	97	85	65.5	33	75
L	103	91	67	34.5	77
XL	109	97	69	36	79.5
2XL	115	103	70.5	37.5	82

How to read the chart

Every rashguard size guide starts with chest, and this one is no different. Find the size closest to your number, then check waist and back length. If those are close too, you're done.

Sleeve length is the tiebreaker for long sleeves. Long arms and a chest right on the line? The bigger size gives you a little more length at the wrist.

Women's cuts are shaped differently, with a hip measurement on the chart. If that's you, use our women's rashguard sizing guide instead of this rashguard size guide for men's cuts.

What if you're between two sizes?

This is where most people get stuck. A few simple rules help:

• Size down if you want a true compression feel and you're slim for your chest size.
• Size up if you have broad shoulders, bigger arms or a bit of a belly, or you just like more room.
• Go by chest, not waist, when the two disagree. A top that's tight at the chest will ride up no matter how the waist fits.

The fabric is 85% polyester and 15% elastane at 230 g/m², so it stretches a lot and snaps back. That's why a size that looks small on the hanger usually feels fine once it's on.

Rashguard fit for BJJ vs MMA

This rashguard size guide works for both sports, because the basic rule is the same: snug and stable. There are a couple of small differences, though.

BJJ and grappling

For grappling, length matters most. You spend a lot of time upside down, and you want the hem to stay tucked. Pair your top with compression shorts or spats so nothing rides up or slides down.

MMA and striking

For MMA, shoulder mobility matters most. Check that you can fully extend your arms without the shirt pulling at the armpits. Lots of fighters go short sleeve here. If you can't decide, our post on short vs long sleeve rashguards breaks it down.

Common rashguard fit mistakes

Even with a good rashguard size guide in hand, these are the usual slip-ups:

• Buying your T-shirt size by default. Rashguards fit closer to the body. Check the numbers instead of guessing.
• Ignoring torso length. A tall, slim grappler might need a size up just for length.
• Sizing up to "grow into it". Loose fabric gets grabbed and bunches. Buy for the body you have today.
• Drying it on high heat. Heat is hard on elastane. Wash cold and hang it to dry so the fit stays the same.

Using a rashguard size guide for team orders

Ordering for your whole club? Sizes XS to 2XL can be mixed in one order. Ask everyone to measure their chest the same way, using the steps above, before you collect sizes.

Sharing one rashguard size guide with the whole team saves a lot of guesswork and grumbling later. Our page on custom gear for clubs explains how team orders work.

Quick answers

Should a rashguard be tight or loose?

Tight, but not restrictive. It should hug your body with no loose fabric, and you should still be able to breathe deeply and lift your arms overhead.

Do rashguards shrink?

A polyester and elastane rashguard shouldn't shrink much if you wash it cold and air-dry it. High heat in the dryer is the usual reason the fit changes.

Should I size up or down in a rashguard?

Go by chest first. Size up if you're between sizes and have broad shoulders or want less compression. Size down only if you want a true compression feel.

Is a rashguard size guide the same for men and women?

Not quite. Women's cuts usually have narrower shoulders, a shaped waist and room at the hips. Use a women's chart when there is one.

How do I know if my rashguard is too small?

Seams dig in, the hem rides up when you raise your arms, or you feel short of breath in hard rounds. Any of those means it's time to size up.

Wrap-up

The best rashguard size guide is the one you use with a tape measure in hand. Measure your chest, match it to the chart, and lean toward the bigger size only when you're in between. A snug fit keeps you grip-free, tucked in and comfortable round after round.

Ready to pick one? Browse our rashguards, made to order in Slovenia in sizes XS to 2XL.