What Should Your Child Wear Under a BJJ Gi? Complete Parent Guide
What Should Kids Wear Under a BJJ Gi? (Complete Parent Guide)
One of the most common questions new BJJ parents ask is: "What should my child wear under their gi?" If your child has just started Brazilian Jiu Jitsu, you're not alone. The good news is that there isn't a complicated answer, but there are a few things every parent should know.
Quick Answer
For most children, the best option is:
✅ A rashguard under the gi jacket
✅ BJJ shorts, sports shorts, or leggings under the gi trousers (optional depending on academy rules)
✅ Appropriate underwear
A rashguard is generally the most comfortable, hygienic and practical choice for training.
Why Wear Something Under a BJJ Gi?
While some adults choose not to wear a base layer under their gi, most children's BJJ classes encourage or expect students to wear something underneath.
There are several benefits:
Better Comfort
BJJ training involves a lot of movement, rolling and grappling. A lightweight rashguard helps prevent rubbing from the gi material and keeps children more comfortable throughout class.
Improved Hygiene
BJJ can be a sweaty sport. A rashguard helps absorb moisture and creates an additional barrier between the skin and the training equipment.
Extra Confidence
Many children feel more comfortable wearing a layer underneath their gi, especially when changing before or after class or if their jacket becomes loose during training.
Is a Rashguard Required?
Every academy has slightly different rules.
Some clubs require rashguards under the gi, while others simply recommend them.
If you're unsure, ask your coach or academy staff.
Even when not required, most experienced BJJ parents find that a rashguard quickly becomes an essential piece of kit.
What Is a Rashguard?
A rashguard is a lightweight athletic top designed specifically for grappling sports such as:
- Brazilian Jiu Jitsu
- Wrestling
- Judo
- MMA
- NoGi BJJ
They are made from stretchy, moisture-wicking materials that help keep children comfortable during training.
Unlike a standard cotton t-shirt, a rashguard won't become heavy with sweat or bunch up underneath the gi.
Can My Child Wear a T-Shirt Under Their Gi?
Yes, especially when they're just starting out.
A plain sports t-shirt is perfectly acceptable at many beginner classes.
However, most parents eventually switch to rashguards because they:
- Stay in place better
- Dry more quickly
- Feel more comfortable
- Last longer with regular training
If your child trains more than once a week, a rashguard is usually worth the investment.
What Should Kids Wear Under BJJ Gi Trousers?
Most children simply wear:
- Regular underwear
- Sports shorts
- Compression shorts
- Leggings
This often comes down to personal preference and academy rules.
Some children prefer compression shorts or leggings as they provide additional comfort and coverage during training.
What About Competitions?
Competition rules can be different from regular classes.
For example, organisations such as IBJJF have specific requirements regarding what athletes may wear underneath their gi.
Before entering a competition, it is always worth checking the event's rules or speaking with your coach.
👉 Read our guide to BJJ competition rules before your child's first event.
How Many Rashguards Does My Child Need?
For children training:
Once Per Week
- 1 rashguard is usually enough
Two to Three Times Per Week
- 2 rashguards are recommended
Four or More Sessions Per Week
- 3+ rashguards make life much easier
Many parents quickly discover that having spare training gear helps keep up with washing and busy schedules.
Common Parent Questions
Can my child train without a rashguard?
Usually yes, unless your academy requires one. A t-shirt can often be used when starting out.
Does my child need branded BJJ clothing?
No. A comfortable rashguard that meets your academy's requirements is normally sufficient.
Can girls wear rashguards under a gi?
Absolutely. Rashguards are commonly worn by both boys and girls training BJJ.
Does a rashguard make a difference?
Most children find them more comfortable than standard t-shirts, particularly during longer training sessions.
Final Thoughts
If you're wondering what your child should wear under a BJJ gi, a rashguard is usually the best option. It improves comfort, helps with hygiene and is designed specifically for the demands of Brazilian Jiu Jitsu training.
For children just starting their BJJ journey, don't worry about buying everything at once. A gi and a suitable base layer are enough to get started, and you can add extra training gear as they progress.
Related Parent Resources
Before purchasing your next gi, you may also find these guides useful: