Pressure, decoded
ATA pressure hyperbaric chambers
ATA (atmospheres absolute) is the pressure a chamber reaches. Sea level is 1.0 ATA, and every step up drives more oxygen into your blood. Soft-shell chambers reach 1.3 to 1.5 ATA; only hard-shell chambers hit the 2.0 ATA used in clinical protocols. Pressure, not brand, is the number that decides what a chamber can do — here is how 1.3, 1.5, 2.0, and 3.0 ATA really compare, and which to buy.
The unit
What ATA means
ATA measures total pressure against sea level, which is 1.0 ATA. Every extra atmosphere equals descending another 33 feet underwater, and it is the same pressure whether a gauge reads it in ATA, PSI, or feet of seawater.
| Pressure | Above ambient | Depth equivalent | Category |
|---|---|---|---|
| 1.0 ATA | 0 PSI (gauge) | Sea level | Normal air |
| 1.3 ATA | ≈ 4.4 PSI | ≈ 10 ft underwater | Mild / soft |
| 1.5 ATA | ≈ 7.3 PSI | ≈ 16.5 ft underwater | Upper mild |
| 2.0 ATA | ≈ 14.7 PSI | ≈ 33 ft underwater | Clinical / hard |
| 3.0 ATA | ≈ 29.4 PSI | ≈ 66 ft underwater | Emergency |
One atmosphere is about 14.7 PSI or 760 mmHg. Because hyperbaric therapy was born from diving medicine, gauges and studies still borrow the feet-of-seawater scale (Caroline Fife, M.D.). New to chambers entirely? Start with what a hyperbaric chamber is.
Why the number matters
More pressure, more oxygen — but read the fine print
Pressure works through Henry’s law: the higher the pressure, the more oxygen dissolves directly into your blood plasma, reaching tissue that red blood cells alone cannot. That is real. What vendors skip is that the pressure is only half the equation.
What you breathe at that pressure decides the result. By the gas-law math, breathing plain room air at 1.3 ATA works out to roughly 27% oxygen at sea level — a modest lift you could nearly match with a mask in your living room (Caroline Fife, M.D.). The meaningful gain in a mild chamber comes from pairing it with an oxygen concentrator that raises the oxygen to around 90 to 95%.
A hard-shell at 2.0 ATA delivering 100% oxygen is a far bigger jump — several times the oxygen your blood carries at sea level. So when you compare chambers, read two numbers, never one: the ATA pressure and how the oxygen is delivered. A high ATA on the label means little if the chamber only circulates ambient air.
Side by side
1.3 vs 1.5 vs 2.0 vs 3.0 ATA, compared
Each pressure level suits a different goal, chamber, and user. Higher is not a ranking — it is a trade-off between oxygen delivered, comfort, oversight, and cost.
| 1.3 ATA | 1.5 ATA | 2.0 ATA | 3.0 ATA | |
|---|---|---|---|---|
| Vs sea level | +30% pressure | +50% pressure | Double (2×) | Triple (3×) |
| Chamber | Soft-shell | Soft or hard | Hard-shell | Hard (hospital) |
| Oxygen source | Ambient air ± concentrator | Concentrator (~90–95%) | 100% medical O₂ | 100% medical O₂ |
| FDA status | Cleared (Rx) for acute mountain sickness | Off-label wellness | FDA-recognized indications | Emergency indications |
| Oversight | Home use | Home / wellness centre | Medical supervision | Hospital only |
| Best for | Everyday recovery, wellness | Frequent, stronger wellness | Clinical protocols | Decompression sickness, CO poisoning |
1.3–1.5 ATA is the mild, home-friendly range; 2.0 ATA is the clinical workhorse and the pressure behind most studied protocols; 3.0 ATA is hospital-only for emergencies. The graded evidence for what each actually treats is in our hyperbaric chamber benefits guide.
The myth to drop
Does higher ATA mean better?
No — the biggest number is not automatically the best buy. Pressure should match the goal, not the ego.
For clinical, FDA-recognized indications, 2.0 ATA and above is the studied standard and what insurance recognizes (UHMS, FDA). But higher is not automatically better: published research on mild HBOT reports measurable effects at 1.5 ATA for some wellness uses, where the evidence is still mixed — we grade it honestly in our benefits guide. And pushing higher carries a cost: because oxygen toxicity is driven by pressure and time, adverse events become more common above 2.0 ATA, which is exactly why those pressures run under medical supervision (NLM overview).
The practical rule: choose pressure by goal, tolerance, and frequency. A comfortable 1.3 to 1.5 ATA you will actually use five days a week beats a 3.0 ATA chamber you dread. Chasing the highest ATA usually just adds cost, safety overhead, and complexity you do not need.
What reaches what
Which shell hits which pressure
Pressure ceiling tracks build. A flexible soft-shell physically can’t hold clinical pressure; a rigid hard-shell can. That single fact drives most of the buying decision.
| Soft-shell | Hard-shell | |
|---|---|---|
| Pressure ceiling | 1.3 – 1.5 ATA (some to 1.6) | 2.0 – 3.0 ATA |
| Build | Flexible, zip-up, portable | Rigid steel or acrylic vessel |
| Oxygen | Concentrator via mask (~90–95%) | 100% medical-grade O₂ |
| Where it fits | Home, on your own schedule | Clinic, or a serious home setup |
In our own range, the soft-shell Superhuman S1 covers the 1.3 to 1.5 ATA band, while the hard-shell Superhuman L1 reaches a true 2.0 ATA. The deeper build comparison is in hard-shell vs soft-shell, and the pressure-by-pressure walkthrough is in pressure levels explained.
The decision
Which ATA should you buy?
Work backward from the goal, not the spec sheet. Two questions settle it: what are you using it for, and how often?
For everyday recovery, sleep, and general wellness, a 1.3 to 1.5 ATA soft-shell with an oxygen concentrator is the practical choice: comfortable, home-friendly, and easy to use daily. For the clinical, evidence-backed protocols — or if you simply want the pressure the research is built on — you need a hard-shell that reaches a true 2.0 ATA. Almost no one buying for home needs 3.0 ATA; that range belongs in hospitals. That maps onto our range directly: the Superhuman S1 ($15,000) covers the 1.3 to 1.5 ATA end, and a hard-shell like the Superhuman L1 ($49,000) delivers a true 2.0 ATA.
Once you know your pressure, compare real models in best hyperbaric chambers, size the budget with the cost guide and cost calculator, and when you’re ready, browse chambers for sale. Buying for the house? The home hyperbaric chamber guide covers the rest.
FAQ
ATA questions
What does ATA mean in a hyperbaric chamber?
ATA stands for atmospheres absolute — the total pressure inside the chamber measured against sea level, which is 1.0 ATA. A chamber at 2.0 ATA holds double sea-level pressure, the equivalent of being about 33 feet underwater. The higher the ATA, the more oxygen is driven into your blood plasma, which is the whole point of pressurizing the chamber.
How many PSI is 2.0 ATA?
One atmosphere equals about 14.7 PSI, so 2.0 ATA is roughly 14.7 PSI above normal air pressure (about 29.4 PSI absolute). For reference, 1.3 ATA is about 4.4 PSI above ambient and 1.5 ATA is about 7.3 PSI. Soft chambers usually display PSI; clinical chambers and studies use ATA. They describe the same pressure on different scales.
What is the difference between 1.3, 1.5, and 2.0 ATA?
1.3 ATA is mild pressure reached by soft-shell home chambers (30% above sea level). 1.5 ATA is the upper end of "mild HBOT," available in advanced soft chambers or entry hard chambers. 2.0 ATA doubles sea-level pressure, is delivered only by rigid hard-shell chambers with 100% oxygen, and is the pressure used in most FDA-recognized clinical protocols.
Is 2.0 ATA better than 1.5 ATA?
Not automatically. 2.0 ATA drives more oxygen into the blood and is the standard for clinical, FDA-recognized indications. But some studies find 1.5 ATA comparable for certain uses, and adverse events such as ear barotrauma and oxygen toxicity become more common above 2.0 ATA, so higher pressure means more oversight. The right pressure depends on your goal, tolerance, and how often you plan to use it, not the biggest number.
Does a soft chamber at 1.3 ATA actually do anything?
It depends on what you breathe. Breathing plain room air at 1.3 ATA is, by the gas-law math, roughly equivalent to breathing 27% oxygen at sea level — a modest lift. The meaningful gain comes from pairing a soft chamber with an oxygen concentrator, which raises the oxygen to around 90–95%. Without a concentrator, a mild chamber on ambient air alone is limited.
What ATA do hospitals use?
Hospital and clinical hyperbaric protocols run at 2.0 to 3.0 ATA with 100% oxygen, under medical supervision. 2.0 to 2.5 ATA covers most FDA-recognized indications such as non-healing wounds and radiation injury, while 3.0 ATA (about 66 feet of seawater) is reserved for emergencies like decompression sickness and severe carbon monoxide poisoning.
What ATA is best for a home hyperbaric chamber?
For general wellness and recovery at home, 1.3 to 1.5 ATA in a soft-shell (paired with an oxygen concentrator) covers most needs and is easy to tolerate daily. If your goal is the clinical, evidence-backed protocols, you need a hard-shell that reaches a true 2.0 ATA. Match the pressure to your goal — our best hyperbaric chambers and cost guides help you decide.
Last updated: July 2026. This guide is educational and does not replace medical advice. Consult a qualified physician before starting hyperbaric oxygen therapy.