If you are new to jiu jitsu, the gear list can feel confusing. Two items come up again and again: the kimono, usually called a gi, and the rash guard. Both are worn during training, yet they are made from different materials, used in different situations, and require different care. This guide explains what each item is, how they compare side by side, and how to decide which one you actually need.
What Is a Jiu Jitsu Kimono (Gi)?
A jiu jitsu kimono is a thick, durable two piece uniform made up of a jacket and a pair of pants, tied closed with a belt. The fabric is usually woven cotton, and the jacket is reinforced at the collar, shoulders, and armpits to survive constant gripping and pulling.
The belt shows rank, and beginners normally start with a plain white belt. Some schools include the belt with the uniform, while others sell it separately.
What Is a Rash Guard?
A rash guard is a tight fitting top made from stretch fabric, typically a blend of polyester and spandex. It was originally designed for water sports, where it protects skin from sun and friction. In jiu jitsu it does something similar: it stays close to the body, moves sweat away from the skin, and reduces irritation from mat contact.
Rash guards come in short sleeve and long sleeve versions. They are worn with shorts or compression pants, since there is no jacket or belt involved.
Quick Comparison at a Glance
- Main use: gi for gi training, rash guard for no-gi training.
- Fabric: gi uses heavy woven cotton; rash guard uses stretch synthetic fabric.
- Fit: gi is loose but fitted enough to grip; rash guard is tight against the skin.
- Gripping: gi offers collar, sleeve, and belt grips; rash guard offers almost no grip points.
- Weight: gi is heavy and warm; rash guard is light and cool.
- Drying time: gi takes longer to wash and dry; rash guard dries quickly.
- Cost: a full gi usually costs more than a basic rash guard set.
Fabric and Construction
The gi jacket is made from a woven cotton weave. The most common types are single weave, which is lighter and cooler, and double weave, which is heavier and more durable. Pearl weave is another popular option that balances weight and strength. Pants are usually cotton or a cotton-synthetic blend, often with reinforced knees.
Rash guards are knit from synthetic fibers. The stretch allows a full range of motion, and the smooth surface reduces friction against the mat. Flatlock stitching is common because it sits flat and helps prevent chafing along the seams.
Fit and Sizing
Gi sizing is based mainly on height and weight. The fit should be snug enough that an opponent cannot easily slip a hand inside the jacket, but loose enough that you can move freely. Sleeves must reach a certain length, and pants should not be too short.
Rash guard sizing is closer to normal clothing sizes, though the fit should be tight without feeling restrictive. If the fabric bunches or rolls up during movement, it is probably too large.
Training Style: Gi vs No-Gi
The biggest practical difference between the two comes down to the training format.
- Gi training: the uniform creates grips. Techniques rely on controlling the collar, sleeves, belt, and pant legs. Rounds tend to be slower and more methodical.
- No-gi training: without a jacket, grips come from the body, wrists, and limbs. Rounds tend to be faster and depend more on positioning and control.
Many schools teach both formats, and competitors often train both. If you plan to attend both types of classes, you will need both kinds of gear.
Wearing Them Together
Rash guards are commonly worn under the gi jacket. Doing so adds a layer of protection, absorbs sweat, and can reduce the chance of mat burn and skin irritation. Short sleeve and long sleeve versions both work, though long sleeve offers more coverage.
Compression shorts under gi pants serve a similar purpose. Layering keeps the heavier uniform from rubbing directly against bare skin.
Care, Cleaning, and Lifespan
Both items should be washed after every training session. Skin infections spread easily on shared mats, so hygiene matters for you and your training partners.
- Wash cold or warm with a mild detergent.
- Skip fabric softener, which can leave residue behind.
- Air dry when possible. Heat can shrink cotton gis and break down the stretch in rash guards.
- Wash right after training to prevent odor and bacteria from settling into the fabric.
A well cared for gi can last several years, even with frequent use. Rash guards usually wear out sooner, because the fabric thins and the seams stretch over time.
Cost and Value
A basic gi generally costs more than a rash guard set, mostly because of the amount of fabric and the reinforced construction. Entry level gis are affordable, while competition gis with lighter weaves tend to cost more. Rash guards range from budget options to premium ones, but the difference is often in fit and durability rather than protection.
If your budget is limited, start with the gear your school requires. Most gyms ask for a gi in gi classes and a rash guard with shorts in no-gi classes.
Choosing Your First Set of Gear
- Ask your school what uniform is required for each class.
- Check whether a belt comes with the gi or is sold separately.
- Choose a gi weight that suits your climate; lighter weaves are cooler.
- Pick a rash guard in your normal size with a snug fit.
- Buy two rash guards if you train often, so one can dry while you wear the other.
- Wash everything after each session and air dry when you can.
Common Questions About Jiu Jitsu Gear
Can I wear a rash guard without a gi? Yes. That is exactly what no-gi training calls for. A rash guard paired with shorts or compression pants is the standard no-gi uniform.
Can I wear a regular t-shirt instead of a rash guard? Some schools allow it, but a rash guard handles sweat better, causes less chafing, and holds its shape instead of stretching or tearing.
How many gis do I need? One is enough to start. Two is convenient if you train several days a week, since it gives the first gi time to dry.
Do rash guards prevent skin infections? They reduce direct skin-to-mat contact, which helps, but they do not replace washing your gear and yourself after every session.
The Bottom Line
The kimono and the rash guard are both essential jiu jitsu gear, but they are not interchangeable. The gi is a heavy woven uniform used for gi training, where grips and control points shape the techniques. The rash guard is a light, stretchy layer used for no-gi training and often worn under the gi for extra comfort and protection. Choose based on the classes you attend, keep both clean and dry, and replace them when the fabric or seams show real wear.
For more practical guidance, explore related articles on workout clothing care, laundry tips for athletic gear, and beginner fitness questions.