If you’ve ever looked at the tag on your flame-resistant gear and noticed an ATPV number, you’re not alone.
A lot of workers see something like 8 cal/cm² or 25 cal/cm² and wonder what it actually means, and whether it’s enough protection for the job they do.
That’s what this guide is for.
ATPV is one of the most important numbers you’ll see on arc-rated FR clothing, especially if you work around energized equipment. Once you understand what it means, choosing the right gear gets a lot clearer.
What Does ATPV Mean?
This quick video breaks down what ATPV means and why it matters on the job.
What Is Arc Thermal Protection Value (ATPV)?
ATPV stands for Arc Thermal Performance Value.
It tells you how much arc flash energy an FR fabric or garment can handle before it stops protecting you.
ATPV is measured in:
cal/cm² (calories per square centimeter)
Here’s the easiest way to remember it:
Higher ATPV = higher arc flash protection.
So if your work shirt has an ATPV rating of 8 cal/cm², that means it can withstand 8 calories of energy per square centimeter during an arc flash exposure before there’s a 50% chance of a second-degree burn.
What Does “Calories” Mean on FR Clothing?
When people hear “calories,” they usually think food. But on FR clothing labels, calories are a way to measure heat energy.
A simple way to understand it is this:
One calorie is like holding a lighter against your skin for one second.
That’s why ATPV matters. It gives you a real way to compare protection levels instead of guessing based on thickness, weight, or how warm the fabric feels.
Why ATPV Matters on the Job
Arc flash hazards are fast and intense. If something goes wrong, it happens in a split second, and the heat can be extreme.
ATPV matters because it helps you confirm whether your clothing is built for the hazards you may face on the job, not just “FR” in name, but protection you can actually trust.
How to Find the ATPV Rating on Your FR Clothing
The easiest way to confirm your ATPV rating is to check your garment label or the product page online.
Arc-rated FR clothing should clearly show the ATPV rating in cal/cm². Depending on the garment, you may also see compliance information listed, such as ASTM 1506 / NFPA 2112, along with other safety details.
If there’s no ATPV listed, the garment may still be flame-resistant, but it may not provide arc flash protection.
What ATPV Level Do You Need?
This depends on your job tasks and the hazards on site.
Most worksites determine minimum protection requirements using an arc flash hazard analysis. That’s why the answer isn’t always “higher is better.”
The real goal is:
Wear the ATPV level your site requires.
Always follow your employer’s PPE program, and don’t assume one set of clothing works for every site, every task, or every piece of equipment.
ATPV in Winter: Why Layering Matters
Cold weather adds another challenge. You need warmth and comfort to make it through the shift, but you still need the right protection.
If you’re shopping for the best FR clothing for the winter, remember that cold weather usually means more layers, and every layer plays a role in your overall protection. Knowing your ATPV helps you stay warm without cutting corners on safety.
Picking the Right FR Jacket for Winter
A winter jacket can feel warm and still be the wrong choice for electrical work. When you’re layering up, it’s important that your outerwear still fits your arc-rated system and matches the hazards on site.
That’s why ATPV matters even more in cold weather. It helps you choose warm FR jackets and layers that keep you comfortable without compromising protection. It’s also what separates the best FR jackets from jackets that are just warm but not built for the hazards.
MWG Apparel offers a full range of arc-rated FR gear, from Base Layers to Winter Outerwear, with protection levels from ATPV 4.3 to 48. Everything is third-party tested to make sure it holds up against real workplace hazards.
Want to go one step further? In our next blog, we’ll show you how to layer arc-rated FR clothing for winter, so you can stay warm without sacrificing protection.
Explore MWG Apparel’s arc-rated FR workwear and build a system that keeps you protected, comfortable, and ready for the job.