Sizing
How a rash guard should actually fit
Fit is the single most common reason a rash guard gets worn twice and then lives in a drawer. Guard Theory sizing is not finalised, so this page teaches you how to judge fit generally rather than selling you a number.
The short version
A rash guard should be tight enough that it cannot be gripped as a handle, and loose enough that it does not restrict a deep shoulder rotation. If you can pinch a fold of fabric at your ribs and pull it more than a couple of centimetres away from your body, it is too big. If you cannot reach across your body and touch the opposite shoulder blade without the whole garment dragging, it is too small.
Compression and tightness are not the same thing. Compression is even pressure across a panel. Tightness is localised restriction, usually at the armpit, the shoulder seam or the neck opening, and it is a pattern problem rather than a size problem. Going up a size to fix a bad armhole usually produces a garment that is simultaneously too tight in one place and loose everywhere else.
Checking fit properly
Do these on the mat, not in front of a mirror. A rash guard that fits standing still is not the same as one that fits in a scramble.
- Shrimp and recover. The hem should stay put. If it climbs above your navel, the body length is short for your torso, which is a separate problem from your chest size.
- Post a hand and rotate. The shoulder seam should sit on the point of your shoulder throughout. A seam that drags across the deltoid will chafe within one round.
- Take an underhook. Nothing should bunch in the armpit. Bunching is where abrasion and holes start.
- Have someone grip the sleeve. There should be very little to hold. A sleeve that can be balled up in a fist is a handle you are giving away.
- Invert, if you invert. Watch what the hem and the neck opening do upside down.
Measuring yourself
Use a soft tape, stand relaxed, and do not hold your breath or flex. Have someone else do it if you can, because self-measuring the chest reliably reads small. Record centimetres and inches so you can use any brand chart.
- Chest. Around the fullest part, tape level under the armpits and parallel to the floor.
- Torso length. From the bony point at the top of your shoulder, down the front, to where you want the hem to sit. This is the measurement almost every size chart omits and the one that most often explains why the right chest size still rides up.
- Sleeve length. From that same shoulder point, along a slightly bent arm, to the wrist bone.
- Waist. At the natural waist, not at your belt line.
- Weight and height. Most grappling charts are built around these two first, which is why they misfit anyone with an unusual ratio.
Guard Theory sizing
Not yet published
We are not going to publish a size chart before the pattern is graded. Invented measurements are worse than no measurements, because people order against them.
| Size | Chest | Torso length | Sleeve |
|---|---|---|---|
| Range not confirmed | Pending | Pending | Pending |
If you tell us your size preference when you join the Edition 001 list, it feeds directly into how the run is split across the range.
Between two sizes?
For no-gi training, size down if the smaller size passes the underhook and rotation checks, because a rash guard stretches slightly with wear and a loose one gets gripped. Size up if you are between sizes on torso length specifically, since length is the harder problem to live with. If you are competing under a ruleset with garment requirements, check the current published rules yourself before ordering anything from anyone.
None of this replaces trying it on. Any brand that tells you a chart is definitive is selling you a return.