Hyperbaric · 6 min read
Understanding ATA: What the Pressure Numbers Mean
ATA (atmospheres absolute) is a unit of total pressure measured relative to a vacuum, where everyday sea-level air pressure equals 1.0 ATA.
Quick answer
- 1.0 ATA is normal sea-level pressure; higher ratings indicate progressively greater pressure, with 2.0 ATA being double.
- Mild wellness use typically stays in the 1.3–1.5 ATA range.
- A chamber's maximum rated ATA helps you match it to your space and intended use.
When you compare hyperbaric chambers you'll see pressures listed in ATA. Here's a simple explanation of what those numbers describe.
ATA in plain terms
ATA stands for 'atmospheres absolute.' It measures total pressure relative to a vacuum. At sea level, the air around you is about 1.0 ATA.
A chamber's pressure rating describes how far above sea-level pressure it operates; 2.0 ATA is double sea-level pressure.
Why the range matters
Higher pressure means more oxygen dissolves into the body's fluids. Mild wellness use typically stays in the 1.3–1.5 ATA range, while higher pressures are associated with professional, clinical-grade equipment.
Knowing a chamber's maximum rated pressure helps you match it to your intended use and confirm it fits the space and operating routine you have in mind.
ATA, PSI, and other units you'll see on spec sheets
Manufacturers describe pressure in different units. Some spec sheets list absolute pressure while others list only the amount above ambient, so check which convention is used before comparing models.
You may also see kilopascals (kPa) on imported equipment. Check the manufacturer's documentation to understand whether a value is absolute or above ambient.
An everyday reference point
Pressure changes are easier to picture with familiar comparisons such as depth underwater or cabin pressure. Follow the equipment documentation for operating ranges and session guidance.
That is also why your ears notice the transition: the same gentle 'ear pop' you feel on a plane's descent is what equalizing feels like as a chamber comes up to pressure.
How rated ATA relates to chamber construction
Soft-shell (fabric) chambers are typically rated in the 1.3–1.5 ATA range; that ceiling is a product of the zippered fabric construction. Hard-shell chambers use rigid vessels and can carry higher ratings, which is one reason they cost and weigh more.
A chamber's rated ATA is an operating specification of the equipment — like a tire's pressure rating — not a recommendation for how anyone should use it. If you're comparing models, our soft vs hard shell guide walks through how the rating interacts with size, portability, and budget.
Common questions
Is a higher ATA always better?
Not necessarily — 'better' depends on your goals, the equipment's design, and how it will be used. Mild wellness use commonly stays in the 1.3–1.5 ATA range.