450gsm vs 350gsm BJJ Gi: What Does Cotton Weight Actually Mean?

450gsm vs 350gsm BJJ Gi: What Does Cotton Weight Actually Mean?

When shopping for a BJJ gi, you'll often see a number followed by "gsm" in the product description. It's one of the most commonly misunderstood specs in martial arts gear — and one of the most important. Understanding what GSM means can help you choose the right gi for your training style, climate, and goals.

What Does GSM Mean?

GSM stands for grams per square metre. It's a measurement of fabric density — specifically, how much a one-square-metre piece of the fabric weighs. The higher the GSM, the denser and heavier the fabric.

In the context of BJJ gis, GSM refers to the weight of the jacket fabric. It directly affects:

• How durable the gi is
• How heavy it feels to wear
• How warm it is during training
• How stiff or soft it feels
• How quickly it dries after washing

Common BJJ Gi Fabric Weights

350gsm — Lightweight

• Feel: Soft, light, and flexible straight out of the bag
• Durability: Lower — more prone to wear over time
• Temperature: Cooler to train in — ideal for hot gyms or summer training
• Best for: Warm climates, competition use, athletes who prioritise mobility

450gsm — Mid-Weight

• Feel: Slightly stiffer initially, softens with washing and wear
• Durability: Excellent — handles daily training and frequent washing well
• Temperature: Moderate — comfortable in most training environments
• Best for: Everyday training, most climates, athletes who want longevity

550gsm — Heavyweight

• Feel: Dense, stiff, and substantial
• Durability: Maximum — built to last years of hard training
• Temperature: Warm — can be uncomfortable in hot gyms
• Best for: Cold climates, very frequent trainers needing maximum durability

Which GSM is Right for You?

Training Frequency

If you train five or more times per week, a heavier gi (450gsm+) will hold up better to constant washing and physical stress. Two or three times per week? A lighter gi will serve you well.

Climate and Gym Temperature

Training in a warm gym? A lighter 350gsm gi keeps you cooler. Training in a cold gym or UK winter? A heavier gi provides natural warmth.

Competition vs Training

Many competitors own two gis — a lighter one for competition and a heavier one for daily training. If you're starting out, a mid-weight 450gsm gi is the most versatile choice.

Does GSM Affect Shrinkage?

Yes — heavier cotton gis can shrink more in the wash if not cared for properly. Always cold wash (30°C or below) and hang dry. Never tumble dry a cotton gi regardless of weight.

What About the Weave?

• Single weave: Lighter and more affordable, typically 350–400gsm
• Double weave: Heavier and more durable, typically 500gsm+
• Gold weave: A hybrid — lighter than double but more durable than single, typically 400–450gsm
• Pearl weave: The most popular modern weave — lightweight but durable, typically 350–450gsm

The Verdict

For most grapplers training regularly in a temperate climate like the UK, a 450gsm gi is the better all-round choice. It's durable enough for frequent training, comfortable in most gym temperatures, and will last significantly longer under the same conditions. If you compete regularly, consider a lighter 350gsm gi as a second option specifically for tournament day.

Don't obsess over GSM at the expense of fit and quality. A well-made 450gsm gi that fits correctly will outperform a poorly made 350gsm gi every time.