The A-size system used in BJJ gis looks straightforward until you try to apply it across brands. An A2 from one manufacturer can fit identically to an A3 from another, because there's no standardized measurement behind the letters. Height, weight, and torso length all factor into which size actually works for a given body, which means a size chart from one brand tells you almost nothing about a different brand's cut. The only reliable approach is checking the actual centimeter measurements that most brands publish separately, covering chest circumference, jacket length, and pant inseam.
Shrinkage compounds the sizing problem. Cotton gis, which make up the majority of what you'll find in BJJ, shrink noticeably after the first wash even in cold water. Most cotton gis lose somewhere between 3% and 8% of their dimensions after the initial wash cycle. Buying a gi that fits perfectly before washing almost guarantees it won't fit after it. Honestly, experienced grapplers typically buy a size that feels slightly large off the rack, expecting it to settle into the right fit after the first cold wash.
Weave type is the construction pattern of the fabric itself. Single weave gis use a thinner structure that dries faster, weighs less, and breathes better in hot gyms. They're the right call for high-volume training, summer months, or travel. The trade-off is durability: single weave wears down at friction points (knees, collar base, inner forearms) faster than denser options. Pearl weave is the most common construction in modern gis, offering a middle ground between weight and durability. Double weave is significantly heavier and rarely seen in current competition training, though some practitioners who learned in earlier generations still prefer it.
Fabric weight, measured in GSM (grams per square meter), tells you more precisely how heavy a gi will actually feel. A pearl weave jacket at 450 GSM will be noticeably lighter and cooler than one at 750 GSM in the same weave. Most competition-focused jiu-jitsu gis in the current market sit in the 400-550 GSM range for the jacket. Lower GSM means cooler and faster-drying; higher GSM typically means longer lasting, but warmer and slower to dry after training.
For anyone planning to compete, color is a filter that should come before aesthetics. Major BJJ federations including IBJJF and CBJJ only approve white, royal blue, and black gis at sanctioned events. Grey, camo, green, and other training colors are fine for the mat, but they'll get you rejected at competition check-in. In practice, most academies that run competition teams recommend starting with white or blue specifically for this reason, and adding other colors later once competition isn't a priority.
The collar is the most tactically relevant part of the gi. A thicker, stiffer collar is harder for an opponent to grip and requires more effort to establish collar control. The cost is break-in time: a stiff collar can feel uncomfortable for the first few weeks before it softens enough for normal training. Softer collars are comfortable from day one but offer less resistance to gripping. Neither is wrong. It's a genuine trade-off that buying guides usually skip entirely.
Women's specific sizing exists because standard A-sizing was built around male proportions. A woman buying a men's gi in a small size typically ends up with a jacket that fits the torso but has sleeves and a hem that don't match her proportions. Women's specific cuts address the shoulder width, torso length, and sleeve dimensions separately. For kids, sizing follows age and height rather than the A-system, and the jacket hem should allow active movement without dropping past the hips.
The most common care mistake with jiu-jitsu gis is heat. Hot water loosens weave structure over repeated wash cycles. A dryer on high heat can shrink a gi in one cycle far more than months of cold washing. Air drying, always after a cold water wash, is the consistent standard from anyone who has maintained a gi wardrobe through years of regular training. Flipping the gi inside out before washing also protects embroidery and patches from wearing down prematurely.
A gi is the wrong purchase if you train exclusively no-gi. That's obvious, but worth stating clearly: a lot of gyms have shifted toward no-gi or run only occasional gi classes. Buying a quality gi for a gym that barely uses them means spending significantly on equipment that sees minimal use. Ask your coach how many sessions per week involve gi training before committing to a good one.
