Gi jiu-jitsu has one advantage over no-gi for a total beginner: the required uniform is obvious. That said, there are still a handful of details that catch first-timers off guard, things nobody mentions until they show up without them.
The Gi Itself
A jiu-jitsu gi consists of a heavy woven jacket, matching pants, and a white belt for anyone starting fresh. Many gyms have loaner gis available for a genuine first trial class, so it's worth asking before buying one, since gis vary in cut and weave weight and it helps to know your gym's preference before committing to a purchase. Once you're staying with the sport, a mid-weight gi in a standard cut is a sensible first purchase rather than the lightest or most expensive competition-cut option.
What Goes Underneath
A rash guard or compression shirt underneath the gi jacket is standard practice at most gyms, both for hygiene and comfort during long grip battles. For bottoms, athletic shorts or compression shorts under the gi pants serve the same purpose. Some gyms have specific expectations here, so a quick check with an instructor before your first class avoids any awkwardness.
Hygiene Items Nobody Mentions
Fingernails and toenails trimmed short are a genuine safety expectation, not a suggestion, since long nails cause real scratches during close contact. A mouthguard is worth having even for a first class if any live rolling is involved, and flip-flops or sandals for walking to and from the mat, rather than bare feet on locker room floors, are a small detail that matters more than it seems.
What Can Wait
A second gi, a nicer competition belt, and specialty grip tape are all reasonable purchases once you know you're continuing with the sport, but none of them are necessary for a first class or even a first few months of casual training. One gi, appropriate underlayers, and basic hygiene habits are enough to show up prepared.
FAQ
Do I need to buy a gi before my first BJJ class?
Not necessarily. Many gyms offer loaner gis for a genuine first trial class, so it's worth asking before purchasing one yourself.
What do I wear underneath my gi?
A rash guard or compression shirt under the jacket and athletic or compression shorts under the pants is standard practice at most gyms, both for hygiene and comfort.
Are there hygiene requirements for a first gi class?
Yes. Trimmed fingernails and toenails are a genuine safety expectation, and a mouthguard is worth having if any live rolling is involved.