Kids BJJ Gi Sizing Guide — Complete Size Chart for Youth Practitioners
Sizing a kids BJJ gi correctly is more important than sizing an adult gi. Children grow fast, train continuously, and need a gi that is comfortable enough to encourage their enthusiasm for the sport — not one that restricts movement or makes them feel uncomfortable on the mat.
This guide gives you everything you need to size kids BJJ gis correctly — whether you are a parent buying for your child, an academy ordering for your kids program, or a brand building a youth gear range.
How Kids BJJ Gi Sizing Works
Kids BJJ gis use the M (Minor) size system from M0 through M4. Unlike adult sizing which is primarily based on height, kids sizing must account for the significant variation in height and weight at the same age.
Two children both aged 8 years old can differ by 15cm in height and 10kg in weight. Always measure the child rather than relying on age alone.
Kids BJJ Gi Size Chart — M0 to M4
| Size | Height | Weight | Approx Age | Chest |
|---|---|---|---|---|
| M0 | 100–110 cm | 18–24 kg | 4–5 years | 55–60 cm |
| M1 | 110–120 cm | 24–30 kg | 5–7 years | 60–65 cm |
| M2 | 120–130 cm | 30–38 kg | 7–9 years | 65–70 cm |
| M3 | 130–140 cm | 38–45 kg | 9–11 years | 70–75 cm |
| M4 | 140–150 cm | 45–55 kg | 11–13 years | 75–80 cm |
What Happens After M4?
Children who have outgrown M4 (typically 13+ years or tall 11–12 year olds) move into adult sizing:
- Slim teens: A0 (157–163cm)
- Average teens: A1 (163–170cm)
- Girls aged 12+: F1 or F2 from the women’s size range
How to Measure a Child for a BJJ Gi
Step 1 — Height: Stand the child barefoot against a wall. Measure from floor to the top of their head without shoes. This is the primary measurement.
Step 2 — Weight: Use a scale with the child in minimal clothing.
Step 3 — Find the size: Match height to the size chart above. If the child’s weight is at the upper end of the weight range for their height — or if they have a broad, stocky build — consider sizing up.
Step 4 — Order with growth in mind: If the child is at the upper end of an M2 measurement, order M3. The gi will have 3–5cm allowance initially and will fit correctly for longer as the child grows.
How Often Do Kids Need a New Gi?
| Growth stage | How fast they grow | Gi lifespan |
|---|---|---|
| Ages 4–7 | 6–8 cm per year | 12–18 months per size |
| Ages 7–11 | 5–7 cm per year | 12–18 months per size |
| Ages 11–14 | 8–12 cm per year (puberty) | 6–12 months per size |
Plan your academy gi reorder cycle around these growth rates. Most successful academy gi programs offer a twice-yearly ordering window and a size exchange program.
Academy Bulk Order — Kids Size Breakdown
For a class of 40 children aged 5–12 years:
| Size | Qty | Percentage |
|---|---|---|
| M0 | 3 | 7% |
| M1 | 8 | 20% |
| M2 | 12 | 30% |
| M3 | 12 | 30% |
| M4 | 5 | 13% |
Survey your class first if possible — ask parents for their child’s current height. This will give you a more accurate breakdown than a general estimate.
IBJJF Youth Competition Sizing
IBJJF enforces the same sleeve and pant length rules for youth competitors as for adults. The gi must:
- Have sleeves ending within 5cm of the wrist
- Have pants ending within 5cm of the ankle
For youth competitors, order in the correct size with no more than 3–4cm allowance — enough room for washing shrinkage but not enough to fail inspection.
Ordering Custom Kids Gis from Onrox International
All our kids gis are manufactured in the full M0–M4 range with:
- 350–400gsm pearl weave (lighter than adult gis for comfort)
- Soft flexible collar construction
- Reinforced knee patches and crotch seam
- Your academy logo embroidered on chest and back
- Kids rank belts in all colors available
Order Custom Kids BJJ Gis → | Get a Quote →
Frequently Asked Questions
What size gi does a 6-year-old need? A 6-year-old of average height (112–118cm) typically fits M1. Measure their height to confirm. For a child on the taller side of this age group, M2 may be more appropriate.
Can I order half M2 and half M3 in the same order? Yes. We regularly produce mixed size orders. Specify exact quantities per size in the quote form.
How much smaller is M0 vs M1? M0 covers 100–110cm height. M1 covers 110–120cm height. The difference is approximately one size up — suitable for a child who has grown 10cm since their last gi.
Are kids gis pre-shrunk? Yes. All our gis are pre-shrunk. Wash in cold water on arrival to confirm final sizing before the child’s first class.
What belt colors are available for kids? We produce kids belts in white, grey, yellow, orange, green, blue, and purple — covering the standard kids rank systems used by IBJJF-affiliated academies worldwide.
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