HBOT Pressure · ATA · Chamber Comparison
1.3 ATA, 1.5 ATA, 2.0 ATA & 2.5 ATA: Understanding Hyperbaric Chamber Pressure
If you've been comparing hyperbaric chambers, you've probably encountered numbers such as 1.3 ATA, 1.5 ATA, 2.0 ATA and 2.5 ATA.
Those numbers matter — but ATA is not a score where the biggest number automatically means the best chamber.
Understanding what ATA actually measures makes it much easier to compare chambers, research protocols and the different ways HBOT can be delivered.
Start With the Basics
What Does ATA Mean?
ATA stands for atmospheres absolute. It is a measure of total pressure relative to a vacuum.
Normal atmospheric pressure at sea level is approximately 1 ATA.
So when a chamber is operating at 1.5 ATA, the total pressure inside the chamber is approximately one and a half times normal sea-level atmospheric pressure.
An Easy Way to Think About It
1.3 ATA, 1.5 ATA, 2.0 ATA and 2.5 ATA describe progressively higher absolute chamber pressures.
Pressure at a Glance
What Do the Different Numbers Represent?
ATA
A lower-pressure hyperbaric environment often encountered in mild-hyperbaric and wellness systems.
ATA
A common pressure for soft-shell systems and the operating pressure used across ReWell's current soft-shell range.
ATA
A higher-pressure range requiring hard-shell chamber construction and used across many clinical and research protocols.
ATA
A higher-pressure hard-shell capability used in selected clinical and professional settings, with additional training requirements in ReWell's current range.
Why Pressure Matters
HBOT Is About More Than Simply Breathing Extra Oxygen
Pressure changes what happens to gases in the body and changes the partial pressure of oxygen when oxygen is being breathed.
As oxygen partial pressure rises, more oxygen can dissolve directly into blood plasma and become available to tissues.
Research into HBOT also describes downstream effects involving oxygen-sensitive cellular signalling pathways, reactive oxygen and nitrogen species, growth factors and tissue-repair responses.
The important point is that pressure and oxygen delivery work together. ATA alone does not tell you everything about the exposure.
Comparing Chambers
Pressure Is Only One Part of the Chamber
Two chambers operating at different ATA levels are not simply “stronger” and “weaker” versions of the same thing.
Chamber construction, oxygen delivery, operating procedures, intended setting and required training can all differ.
Understanding Each Range
1.3 ATA vs 1.5 ATA vs 2.0 ATA vs 2.5 ATA
Lower-Pressure Hyperbaric
Common in the Wellness Market
1.3 ATA systems are frequently encountered when people begin researching mild or lower-pressure hyperbaric chambers.
When comparing these systems, pressure should not be considered in isolation. Ask what gas is being breathed, how oxygen is supplied and what research is actually relevant to the intended use.
ReWell Soft-Shell Range
Flexible Soft-Shell Access
ReWell's current lying, seated and accessible soft-shell chambers operate at 1.5 ATA.
This gives people a practical route to regular home HBOT through rental or ownership without moving into the higher-pressure hard-shell category.
Explore 1.5 ATA Rentals →Higher-Pressure Hard-Shell
Greater Pressure Capability
ReWell's hard-shell range includes systems operating up to 2.0 ATA, with current models available for both rental and ownership.
Hard-shell construction allows higher chamber pressures and introduces different installation, operating and equipment considerations from a 1.5 ATA soft-shell system.
Higher-Pressure Hard-Shell
Advanced Pressure Capability
ReWell also offers selected 2.5 ATA hard-shell systems for rental and ownership.
ReWell's current 2.5 ATA systems require training before use, reflecting the greater operational requirements that can accompany higher-pressure equipment.
Where does 2.4 ATA fit? ReWell's current ownership range also includes selected Petra and Zeugma hard-shell monoplace chambers operating up to 2.4 ATA. We have kept the main article title focused on the most commonly searched 1.3, 1.5, 2.0 and 2.5 ATA comparisons, but 2.4 ATA is part of ReWell's wider chamber range.
Side-by-Side
Hyperbaric Pressure Comparison
| Pressure | Approx. Absolute Pressure | Typical Chamber Context | ReWell Range |
|---|---|---|---|
| 1.3 ATA | 30% above normal absolute atmospheric pressure | Lower-pressure / mild-hyperbaric systems | Not part of ReWell's current advertised chamber range |
| 1.5 ATA | 50% above normal absolute atmospheric pressure | Common soft-shell pressure | Soft-shell rental & ownership |
| 2.0 ATA | Twice normal absolute atmospheric pressure | Higher-pressure hard-shell systems | Hard-shell rental & ownership |
| 2.4 ATA | 2.4 times normal absolute atmospheric pressure | Selected hard-shell systems | Selected ownership models |
| 2.5 ATA | 2.5 times normal absolute atmospheric pressure | Higher-pressure hard-shell systems | Hard-shell rental & ownership · training required |
One of the Biggest Misconceptions
Is Higher ATA Always Better?
No.
Higher pressure creates a different hyperbaric exposure. It does not guarantee a better result for every person, condition or objective.
Different published studies use different pressures because they are investigating different populations, protocols and outcomes.
In sports-recovery research, for example, a recent meta-analysis found effects across protocols both above and at or below 2.0 ATA rather than showing that only the highest-pressure protocols were useful.
The right question is not “What is the highest ATA I can buy?” It is “What pressure and chamber are appropriate for the way I intend to use HBOT?”
Before Comparing Specifications
Six Questions to Ask About Any Chamber
Research Context
Why You Cannot Separate Pressure From Protocol
Pressure and Oxygen Both Matter
A foundational review explains that HBOT's mechanisms arise from increased inspired oxygen partial pressure as well as increased hydrostatic pressure, with downstream effects involving oxygen-sensitive signalling and tissue responses.
PMID 24984320 →More Than One Pressure Can Be Studied
A systematic review and meta-analysis of exercise-induced muscle injury included protocols both above and at or below 2.0 ATA and found statistically significant recovery effects in both pressure subgroups.
PMID 40784513 →Home vs Higher-Pressure Access
Different Chambers Solve Different Practical Problems
A 1.5 ATA soft-shell system may suit someone who values convenient regular home access.
A higher-pressure hard-shell chamber may make more sense in a clinic, sports, recovery, longevity or other professional setting — or for a suitable private user specifically looking for greater pressure capability.
That is why choosing a chamber should start with intended use rather than simply the specification sheet.
Choosing the Right Pressure
Don't Choose a Chamber by ATA Alone
ReWell's chamber selection and HBOT programmes are guided by Davitt Meenaghan, IBUM-certified Hyperbaric Safety Officer.
“Higher pressure isn't automatically better. The right chamber starts with what you're using it for, who will use it and what kind of access you actually need.”
Davitt can help you compare pressure, chamber type, installation, training requirements and intended use before you rent or purchase.
Discuss Chamber Pressure With Davitt →Keep Exploring
Understand the Chamber, Not Just the Number
Common Questions
HBOT Pressure & ATA FAQs
What does ATA mean in hyperbaric oxygen therapy?
ATA stands for atmospheres absolute. It describes total absolute pressure. Normal atmospheric pressure at sea level is approximately 1 ATA, so a chamber operating at 1.5 ATA is at approximately one and a half times normal sea-level absolute atmospheric pressure.
Is 1.5 ATA considered hyperbaric?
Yes. A chamber operating at 1.5 ATA is above normal atmospheric pressure and therefore creates a hyperbaric environment. ReWell's current soft-shell chamber range operates at 1.5 ATA.
What is the difference between 1.3 ATA and 1.5 ATA?
Both are above normal atmospheric pressure, but 1.5 ATA produces a greater pressure exposure than 1.3 ATA. The complete physiological exposure also depends on what gas is being breathed, oxygen delivery, duration and the wider protocol.
Is 2.0 ATA better than 1.5 ATA?
Not automatically. 2.0 ATA provides greater chamber pressure, but the most appropriate pressure depends on the intended use, evidence, oxygen delivery, chamber type, safety considerations and protocol. Higher pressure should not simply be treated as a better specification.
Why are hard-shell chambers used for higher ATA?
Higher chamber pressures require equipment designed and constructed to safely withstand those pressures. ReWell's current soft-shell range operates at 1.5 ATA, while its hard-shell range extends through 2.0, selected 2.4 and 2.5 ATA systems.
Does higher ATA put more oxygen into the body?
Increasing pressure can increase oxygen partial pressure and the amount of oxygen dissolved in plasma when oxygen is being breathed. However, actual exposure depends on both pressure and oxygen delivery, so ATA should not be interpreted in isolation.
Does higher ATA mean fewer HBOT sessions are needed?
No simple rule links higher ATA with fewer required sessions. Session number, pressure, oxygen exposure, duration and frequency are different parts of the overall protocol.
What pressure are ReWell's chambers?
ReWell's current soft-shell range operates at 1.5 ATA. Hard-shell rental options include 2.0 and 2.5 ATA systems, while the ownership range also includes selected systems operating up to 2.4 ATA. Training is required for ReWell's current 2.5 ATA systems.
Which ATA should I choose for a home chamber?
Start with your intended use rather than a pressure number. Chamber type, who will use it, frequency, available space, oxygen delivery, safety requirements and relevant evidence all matter. ReWell can help you compare the available options before renting or purchasing.
Choosing a Hyperbaric Chamber?
Look Beyond the ATA Number
Pressure matters, but so do chamber type, oxygen delivery, intended use, training and the protocol you are trying to follow. ReWell can help you compare the full picture before choosing a chamber.
This article is for general educational purposes. ATA describes chamber pressure but does not by itself determine the appropriate HBOT protocol or likely outcome. Pressure, oxygen delivery, session duration, medical history, equipment and intended use should all be considered when selecting a hyperbaric chamber or programme.