Build #3 · Week 2 · Launched Jun 12, 2026
LiveBJJMath
Calculators for jiu-jitsu nerds. Weight cuts, tournament points, gi sizing, belt timelines. All of it checked against the actual IBJJF and ADCC rulebooks.
The idea
What it is & why I built it
BJJMath is the MyNubs idea pointed at something I actually do on weekends. Brazilian jiu-jitsu. Same bet underneath. Calculators are one of the few pages AI search hasn't really eaten yet, because people want to punch in their own numbers, not read a paragraph. The niche is just better here.
Grapplers Google some weirdly specific stuff. What IBJJF weight class am I in. How do I cut six pounds by Saturday without feeling like death. What gi size do I order from a brand I've never tried. How long till my next belt. Right now the answers are forum guesses or some random weight-cut thread from 2019. That's the opening.
It lives or dies on whether people trust it. So every calculator cites the actual rulebook, shows the math, and gets checked by a real black belt. That last part I still have to actually do. The weight-cut and injury ones especially lean on here's the range, here are the limits, go talk to a pro.
The build
How it was built
This week was the launch set. Ten calculators across three buckets. Competition stuff: an IBJJF weight class finder, a tournament weight-cut planner, a live points calculator, an age-division lookup. Gear: a gi size finder across the big brands and a shrinkage calculator. Health and training: caloric needs, a belt-timeline estimator, a return-to-roll calculator, a training-load tool.
Came together fast because MyNubs already did the hard part. Same engine underneath. Hand-built pages that load instantly, a methodology page for trust, a cited source on every tool, the structured data that makes it easy for an AI to quote. The math was never the hard part. Getting the rules exactly right and being honest about what a calculator can't tell you is.
Infrastructure's boring on purpose. Domain's at Namecheap, site runs on cheap static hosting. Same setup as MyNubs.
The stack
Tools used
Hand-built static pages build
Same fast, no-framework setup as MyNubs. Ten calculators, instant loads, almost nothing to break.
The 10 calculators tools
Logic pulled straight from the IBJJF and ADCC rulebooks, not numbers guessed off a forum.
Methodology + citations trust
A methodology page and a source on every tool. Practitioner review is next. That's the whole credibility play.
Search + AI plumbing discovery
Schema, sitemap, llms.txt, open to AI crawlers. Built to be the source AI cites for BJJ numbers.
The numbers
Analytics so far
Blank for now. Nothing's indexed yet. It fills in the same way MyNubs did. Impressions first, then positions slowly climbing off page two, then the first clicks. I'll post the real numbers here as they show up, zeros and all. No projections.
The recap
What worked & what I'd do better
What worked
- Reused basically everything from MyNubs, so a ten-calculator site took about a week instead of a month. The second build is way faster than the first. That's the whole reason I'm doing this on repeat.
- Leading with methodology and real rulebook citations means the credibility is there from page one, not bolted on later.
- Picked a niche where the current answers are genuinely bad. Forum guesses, dodgy weight-cut advice. Low bar to be the most trustworthy option.
What I'd do better next time
- I need an actual black belt to review the methodology before I claim anything got reviewed by practitioners. That has to be true or the whole trust angle falls apart.
- The gi sizing and shrinkage numbers need validating against real brand charts. Sizing is the thing people will screenshot and roast me for if it's off.
- The weight-cut and return-to-roll tools carry real risk if someone treats them as medical advice. The 'see a professional' framing needs to be loud, not buried.
- Zero traffic on day one, exactly as expected. Same slow SEO burn as MyNubs. Difference is now I'm running the play twice and letting them stack.