Reddit BJJ gi sizing questions, answered (A1 vs A2 vs A3)

How A-sizing actually works (height first)

BJJ gis are sized on the A-scale, running from A0 (smallest) up through A1, A2, A3, A4 and A5, with variants like A1L (long) or F-sizes for women. The most important thing to understand is that A-sizing is primarily driven by height, then adjusted for build. Weight matters, but height sets the baseline, which is why two people at the same weight but different heights often wear different A-sizes.

This trips people up because they expect gi sizing to work like weight-class sizing. It doesn't. A lean 6-footer and a stocky 5'8″ competitor can weigh the same and belong in different gis. Start from height on the chart, then nudge for build, and you'll be close.

The reason height leads is structural: a gi's jacket length, sleeve length, and pant length all key off height, and those are the dimensions you can't easily adjust after the fact. Girth — how roomy the jacket and pants are — is more forgiving, since a slightly loose or snug fit through the body still works. Get the length right first, then worry about how it sits around your build.

A1 vs A2 vs A3: where the lines fall

The exact height ranges shift between brands, but as a rough orientation: A1 tends to suit shorter adults, A2 covers a large middle band of average-height grapplers, and A3 fits taller builds, with A4 and A5 for the tallest and largest. Because A2 covers such a wide swath of people, it's the most common adult size and the one most “am I an A2 or A3?” questions circle around.

The honest answer to “A2 or A3?” is: check the specific brand's chart against your height, then let build and shrinkage break the tie. There's no universal cutoff, which is exactly why the question comes up so often. Don't guess from what a training partner wears — their brand may size differently.

Between sizes? The shrinkage rule

Being between sizes is the most common sizing predicament, and the deciding factor is shrinkage. Cotton gis shrink, mostly from heat, so if a gi is 100% cotton and not pre-shrunk, many grapplers size up slightly and let it shrink into a good fit. If a gi is pre-shrunk or you plan to wash cold and hang-dry, size to the chart rather than up.

The mistake is sizing up “for shrinkage” on a pre-shrunk gi and ending up swimming in it. Read the product description: if it says pre-shrunk, trust the chart. If it doesn't, expect a few percent of shrink with warm washes and drying. Our shrinkage calculator estimates how much a given fabric and wash routine will shrink, so you can size with that in mind.

“I'm tall and skinny” / “short and stocky”

The two builds that break standard charts are tall-and-lean and short-and-stocky, and both are constant sources of sizing threads. If you're tall and slim, a size that covers your height may be baggy in the torso; look for brands with tall or slim cuts, or an A-size with a trimmer fit. If you're short and muscular, a size that fits your build may be too long in the sleeves and pants; a shorter cut or an A-size down with room in the shoulders can work better.

The practical move for awkward builds is to prioritize the dimension that can't be fixed — usually length — and accept some looseness elsewhere, or choose a brand known for offering more cuts. Some brands sell jacket and pants separately or offer half-sizes, which solves this neatly for hard-to-fit bodies.

If you're stuck between two sizes for an awkward build, the general rule is to size for the dimension that would be unwearable if wrong. Sleeves and pants that are too short can make a gi illegal for competition and uncomfortable to train in, whereas a bit of extra room in the body is merely cosmetic. When in doubt, protect length and accept some looseness.

Women's sizing versus A-sizes

Women's sizing comes up often, and the recurring advice is to look for brands offering dedicated women's cuts or F-sizes rather than forcing a men's A-size to work. A men's A-cut is shaped for a different build, so even at the right length it often fits poorly through the shoulders, chest, and hips.

If a brand doesn't make a women's gi, a small men's A-size can work as a starting point, but expect to compromise on fit. Where possible, choosing a maker with a women's line is the single biggest upgrade to how the gi fits and moves — more impactful than any brand-tier decision.

Why brand charts differ

A recurring frustration is that an A2 in one brand fits differently from an A2 in another. That's real: there's no enforced standard, so each maker sets its own height and weight ranges and its own cut. This is why the universal advice is to always check the specific brand's chart and never assume your size carries over.

It's also why buying a second gi from a brand you already own is low-risk — you know how they size — while trying a new brand blind is where sizing goes wrong. When switching brands, re-check the chart every time, even for the “same” A-size.

The upshot is to treat every brand as its own system. Bookmark the chart for the brand you're buying, measure yourself fresh each time, and never let “I'm an A2” become a fixed identity that carries across makers. That one habit prevents the majority of sizing regret people post about.

Pants length, sleeve length, and the fist test

Beyond the A-size, a few fit checks tell you whether a gi actually fits. The jacket lapel should cross comfortably, with about a fist of room between your chest and the closed jacket. Sleeves should reach near your wrist bone when your arms are extended — IBJJF has rules about how far up the forearm a sleeve can sit, which matters for competition. Pants should let you squat deeply without binding, with cuffs resting around the top of the foot.

These checks matter because a gi can be the “right” A-size on paper and still fit badly if the cut doesn't suit you. If a gi passes the fist test and the sleeve and pant length are legal and comfortable, you have a good fit regardless of what the label says.

A step-by-step: find your size

Here's the process that resolves almost every sizing thread. First, measure your height and weight. Second, pull up the specific brand's size chart and find the A-size that matches your height, then sanity-check it against weight. Third, adjust for build — trimmer or longer cuts for awkward proportions. Fourth, factor shrinkage: size up slightly only if the gi is cotton and not pre-shrunk.

Our gi size finder does the first pass for you, turning your height and weight into a starting A-size that you then confirm against the brand's chart. Pair it with the shrinkage calculator if you're between sizes, and you'll order online with confidence instead of guesswork.

Done this way, ordering online stops being a gamble. You're not hoping a size works — you're matching your measurements to a specific chart, accounting for shrinkage, and adjusting for build with eyes open. It's also worth checking a retailer's return policy before you buy your first gi in a new brand, so a genuine mismatch is easy to swap rather than a write-off.