Competition
IBJJF rules, explained without the jargon
A plain-English guide to IBJJF rules: how points are scored, how weight and age divisions work, and the gi weigh-in detail that catches people out.
Field notes
The BJJMath blog
Practical, source-backed writing on the things the calculators touch: competition rules, safe weight management, and gear that actually fits.
Competition
How to cut weight for a BJJ tournament — safely
How to make weight for a BJJ tournament safely: sensible weekly loss rates, what to avoid, and when to just compete a division up instead.
Gear
Choosing the right BJJ gi for your size
A practical guide to BJJ gi sizing: how A-sizes map to height and weight, why brands differ, and how shrinkage changes the math.
Competition
IBJJF weight classes, explained simply
A clear guide to IBJJF adult gi weight classes, the gi-on weigh-in rule that trips people up, and how to find the division you actually belong in.
Competition
How IBJJF points actually work
Takedown 2, pass 3, mount 4 — the IBJJF points system explained with the control rule, advantages, and how matches are decided when nobody taps.
Competition
IBJJF age divisions and Masters, explained
How IBJJF age divisions work: the competition-year rule, the Juvenile and Masters 1–7 brackets, and why you can compete down but not up.
Competition
Your first BJJ competition: a complete prep guide
Everything for your first BJJ tournament: picking a division, making weight, what to pack, how weigh-ins and brackets work, and what to expect on the day.
Competition
How IBJJF weigh-ins work (and how to avoid a DQ)
How IBJJF weigh-ins actually work: same-day timing, weighing in your gi, what happens if you miss weight, and how to avoid an avoidable disqualification.
Gear
How much does a BJJ gi weigh?
How much a BJJ gi weighs by weave — pearl weave, double weave, lightweight comp gis — and why it matters for making weight at IBJJF weigh-ins.
Gear
How to shrink (or stop shrinking) a BJJ gi
How BJJ gi shrinkage works: how to shrink a gi that's too big, and how to stop one shrinking when it already fits, by fabric and wash method.
Gear
How to wash a BJJ gi the right way
How to wash a BJJ gi to keep it clean, prevent shrinkage and skin infections, and make it last: temperature, drying, smell, and mat-hygiene basics.
Gear
How to pick your first BJJ gi
How to choose your first BJJ gi: what size to get, what to ignore, IBJJF-legal basics, and the qualities that matter for a beginner's kimono.
Gear
BJJ gear checklist for your first class
What you need for your first BJJ class and what you don't: gi, rashguard, mouthguard, flip-flops, plus the hygiene basics for beginners.
Gear
Gi vs no-gi: which should you start with?
Gi vs no-gi BJJ for beginners: the real differences in pace, grips, rules and gear, and an honest answer on which one to start with.
Health
How many calories should a grappler eat?
How to estimate calories for BJJ using the Mifflin–St Jeor equation, set protein and macros for grappling, and fuel training without crash dieting.
Health
How long does it take to get a BJJ black belt?
How long it really takes to earn a BJJ black belt, the IBJJF minimum time-in-grade rules, and what actually drives how fast you progress.
Health
BJJ belt ranks, explained in order
The BJJ belt order for adults and kids, what each rank means, the stripe system, and how IBJJF time-in-grade rules fit in — a plain guide for beginners.
Health
Returning to BJJ after injury or time off
How to return to BJJ safely after injury or a layoff: easing back in, protecting the injured area, and when to stay off the mat.
Health
BJJ skin infections: prevention and when to stay off the mat
The common BJJ skin infections — ringworm, staph, impetigo, herpes gladiatorum — how to prevent them, and the rule on when to stay off the mat.
Health
How often should you train BJJ?
How many times a week to train BJJ for steady progress without burning out or getting hurt, plus how to read your recovery and the signs of overtraining.