What is GSM in Workwear and Why Does It Matter for Hoodies?

Q: What GSM is best for year-round use?

For most moderate climates, 280-320 GSM offers the best year-round versatility. This range is warm enough for spring/fall, can be layered for winter, and isn't too heavy for cooler summer mornings.

Published on January 23, 2025 | By VizGlo Safety

GSM (grams per square meter) is a measurement that indicates the weight and density of fabric used in workwear hoodies. It directly affects the garment’s warmth, durability, breathability, and overall comfort. In practical terms, a hoodie with 280-320 GSM offers lightweight versatility ideal for layering in mild climates, while 350+ GSM provides heavy-duty insulation necessary for harsh winter conditions. Understanding GSM helps safety managers, procurement teams, and workers select the right hoodie that balances protection, comfort, and cost-effectiveness for their specific work environment—whether construction sites in Texas or oil fields in Alberta. Choosing the wrong GSM means workers will either be uncomfortably hot or dangerously cold, directly impacting productivity and safety compliance.

Heavy-duty hi-vis work hoodies displaying different GSM weights — Different GSM weights in hi-vis work hoodies affect warmth and durability

What is GSM in Workwear?

GSM stands for “grams per square meter” and is the standard unit of measurement for fabric weight in the textile industry. Specifically, it measures how much one square meter of fabric weighs in grams. This metric provides an objective, internationally recognized way to compare the density and thickness of different fabrics, regardless of the material composition (cotton, polyester, fleece blends, etc.).

When manufacturers specify that a hoodie is “320 GSM,” they’re telling you that every square meter of that particular fabric weighs 320 grams. This weight is a direct result of several factors:

Yarn thickness: Thicker yarns result in higher GSM
Weave or knit density: Tighter constructions increase weight
Fiber type: Some fibers are naturally denser than others
Finishing treatments: Brushing or fleece backing adds weight

Important Note: GSM only measures weight—it doesn’t automatically indicate quality. A 400 GSM hoodie isn’t necessarily “better” than a 280 GSM one; it simply serves a different purpose. The key is matching GSM to your operational needs.

Close-up of fabric weight comparison in hi-vis sweatshirts — Fabric density and construction determine the final GSM rating

Why GSM Matters for Hoodies

For workwear hoodies—especially hi-vis sweatshirts and hoodies used in demanding industrial environments—GSM is far more than a technical specification. It’s a critical performance indicator that affects multiple aspects of worker experience and safety:

1. Thermal Insulation

Higher GSM fabrics trap more air between fibers, creating better insulation. A 350+ GSM fleece-lined hoodie can be the difference between productivity and cold-related downtime in sub-zero temperatures.

2. Durability & Longevity

Heavier fabrics (300+ GSM) generally withstand more abrasion and wear, which is crucial for workers who kneel, climb, or work in rugged environments daily. Lower GSM hoodies may need replacement sooner.

3. Breathability & Comfort

Paradoxically, lower GSM (280-300) hoodies breathe better, making them ideal for active work in moderate climates. They prevent overheating while still providing coverage and safety visibility.

4. Cost Efficiency

GSM directly correlates with fabric cost. Ordering the right GSM prevents overspending on unnecessarily heavy garments or under-buying garments that won’t last through a season.

Understanding GSM also helps when evaluating the best material for hi-vis hoodies, as different base materials (cotton-poly blends, 100% polyester, fleece) can achieve the same GSM with different performance characteristics.

Common GSM Ranges and Their Applications

Here’s a practical breakdown of GSM ranges you’ll encounter in the workwear hoodie market, along with their ideal use cases:

GSM Range	Weight Category	Best For	Climate Suitability
240-270 GSM	Lightweight	Summer layering, indoor warehouses, mild weather outdoor work	15-25°C (60-77°F)
280-320 GSM	Medium-Weight	All-season versatility, construction, logistics, road work in moderate climates	5-20°C (41-68°F)
350-400 GSM	Heavy-Duty	Cold weather work, winter construction, outdoor maintenance, northern regions	-10 to 10°C (14-50°F)
400+ GSM	Extra Heavy	Extreme cold, oil & gas, mining in arctic conditions, specialty applications	Below -10°C (14°F)

Workers wearing different weight hi-vis hoodies in various environments — Different work environments require different GSM weights for optimal performance

For specialized winter applications, explore our guide to heavy-duty winter work hoodies for cold climates, which focuses on 350+ GSM options designed for extreme conditions.

Expert Insight: Finding the “Right” GSM

“In all my years of exporting hi-vis workwear, the conversation about hoodies almost always pivots to GSM right after we confirm the safety class (like ANSI Class 3 or EN 20471). Many clients initially believe a higher GSM is automatically better, but I always reframe it: we’re not looking for the highest GSM, we’re looking for the right GSM for the application.

I’ll ask a client in Scandinavia about their winter needs, and we’ll discuss a 350+ GSM, heavy-duty fleece-lined hoodie. But for a client in Australia or the southern US, that same hoodie would be impractical. For them, a 280 GSM hoodie is far more versatile for layering or for cooler mornings. It’s a crucial balance.

GSM directly impacts price, durability, and most importantly, the worker’s comfort and productivity. Choosing the wrong GSM doesn’t just mean a less comfortable hoodie; it means you’ve bought the wrong tool for the job. I’ve seen entire orders returned because procurement bought 400 GSM hoodies for a Texas summer job site—workers refused to wear them, defeating the entire purpose of the investment in high-visibility safety apparel.

The lesson? Always start with your environment and activity level, then work backwards to the appropriate GSM. Don’t let “heavier is better” thinking drive your decision.”

— Senior Export Manager, VizGlo Safety

How to Choose the Right GSM for Your Team

Selecting the optimal GSM for your workwear hoodies requires a systematic evaluation of several factors. Follow this decision framework:

Step 1: Assess Your Climate & Season

What are the average temperatures during your working season?
Will workers be exposed to wind, rain, or snow?
Is the work primarily indoors, outdoors, or mixed?

Example: A construction crew in Minnesota winters needs 350+ GSM; a Phoenix crew needs 280 GSM maximum.

Step 2: Consider Activity Level

High-intensity work (loading, climbing, digging): Lower GSM prevents overheating
Moderate activity (walking inspections, driving): Medium GSM offers flexibility
Static/low movement (gate control, flagging): Higher GSM maintains warmth

Step 3: Factor in Layering Strategy

If your team wears base layers and mid-layers, you can use a lower GSM hoodie as an outer shell. For stand-alone use, higher GSM is necessary.

Step 4: Budget & Longevity Balance

Higher GSM costs more upfront but may last 1.5-2x longer. Calculate cost-per-wear rather than just purchase price. For insights on procurement, see our article on bulk ordering for safety apparel.

Hi-vis pullover hoodie with detailed GSM fabric composition — Quality fabric composition matters as much as GSM weight

GSM vs. Other Performance Factors

While GSM is a crucial specification, it’s not the only factor determining a hoodie’s performance. A complete evaluation should include:

Fiber Composition

A 300 GSM cotton-poly blend performs differently than 300 GSM 100% polyester. Moisture-wicking, drying time, and warmth vary by material.

Fabric Construction

Fleece-lined, brushed interior, or tight-knit exterior constructions all affect warmth and durability independently of GSM alone.

Safety Features

Reflective tape quality, compliance with ANSI standards, and visibility are paramount regardless of weight.

When customizing hoodies for your team, consider integrating company logos and branding elements that won’t compromise the fabric’s core GSM performance.

Frequently Asked Questions About GSM in Workwear

Is a higher GSM always warmer?

Generally yes, but not always. A higher GSM indicates more fabric density, which typically traps more air for insulation. However, fabric construction and fiber type also play major roles. A well-designed 300 GSM fleece-lined hoodie can be warmer than a poorly constructed 350 GSM single-layer hoodie.

Can I use GSM to compare different brands?

Yes, but with caution. GSM provides a standardized weight measurement, making it useful for cross-brand comparison. However, two 320 GSM hoodies from different manufacturers may perform differently due to fiber quality, construction methods, and finishing treatments. Always request samples when possible.

Does GSM affect reflective tape application?

Indirectly, yes. Heavier fabrics (higher GSM) provide a more stable base for sewing reflective tape, which can improve durability and wash resistance. Very lightweight fabrics may require heat-seal reflective materials instead of sewn-on tapes. Learn more about maintaining reflectivity.

What GSM is best for year-round use?

For most moderate climates, 280-320 GSM offers the best year-round versatility. This range is warm enough for spring/fall, can be layered for winter, and isn’t too heavy for cooler summer mornings. However, “year-round” depends heavily on your specific geography—what works in Oregon won’t work in Montana.

How do I verify the GSM of a hoodie?

Reputable manufacturers should list GSM on specification sheets or product tags. For verification, you can cut a 10cm x 10cm (0.01 m²) sample, weigh it in grams, and multiply by 100 to get GSM. Working with certified manufacturers like VizGlo Safety who maintain strict quality control ensures accuracy.

Does GSM impact price significantly?

Yes, absolutely. Higher GSM means more raw material, which directly increases cost. On average, a 350 GSM hoodie might cost 20-30% more than a comparable 280 GSM version. For large fleet orders, this difference compounds quickly, making GSM selection a key budget consideration. See our guide on bulk orders for custom hoodies.