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PSI to ATM Conversion Calculator

Pressure measurements span multiple unit systems, and switching between pounds per square inch (PSI) and standard atmospheres (ATM) is common in industrial, scientific, and engineering work. This converter handles both directions instantly—whether you're calibrating gauges, verifying experimental data, or documenting pressure specifications across different regions that favour different standards.

Last updated:

Creators Wojciech Sas, PhD
4,281 people find this calculator helpful

How to Use the Converter

The two-way conversion interface requires minimal input. Enter a pressure value in either unit and the result appears instantly in the other.

  • PSI to ATM: Type your pressure reading in pounds per square inch and view the equivalent atmospheric pressure.
  • ATM to PSI: Enter standard atmospheres and receive the pressure in PSI.
  • Additional units: The tool supports conversion between many other pressure scales (pascals, bar, kilopascals, and more) if your workflow involves multiple standards.

Bidirectional conversion eliminates the need to remember which direction the math flows, making it ideal for quick checks on site or in the lab.

The Conversion Formula

The relationship between PSI and ATM is fixed by the definition of standard atmospheric pressure. One atmosphere equals the pressure exerted by a 760 mm column of mercury at sea level, which corresponds to approximately 14.696 PSI.

atm = psi × 0.068046

psi = atm × 14.696

  • psi — Pressure in pounds per square inch; the imperial/US customary unit for pressure
  • atm — Pressure in standard atmospheres; the SI-compatible unit based on sea-level atmospheric pressure

Context: When You'll Need This Conversion

PSI dominates in North American engineering and automotive applications, while atmospheres are standard in physics, chemistry, and international scientific communication. Industries often mix the two:

  • Diving and underwater work: Depth-pressure tables use atmospheres, but regulator gauges display PSI.
  • Pneumatic systems: Equipment specifications may list ATM tolerances, but technicians read PSI on shop compressors.
  • Laboratory gas handling: Safety protocols reference atmospheric pressure, while delivery manifolds show PSI.
  • Aerospace: Cabin pressurization and testing often cross between unit systems depending on the engineering standard cited.

Practical Conversion Tips

Avoid common pitfalls when working across pressure units.

  1. Gauge pressure vs. absolute pressure — PSI gauges often read zero at sea level even though 14.7 PSI of absolute pressure exists. Always confirm whether your instrument shows gauge (relative) or absolute pressure before converting to atmospheres.
  2. Precision for critical work — The conversion factor 0.068046 is sufficient for most purposes, but scientific applications may require more decimal places or unit-specific standards (like technical atmospheres, 1 at = 98,066.5 Pa).
  3. Temperature and altitude effects — These conversion factors assume standard conditions. In real systems, temperature changes and altitude variations alter actual pressure readings, so convert the raw number first, then apply corrections if needed.

Quick Reference Table

Common pressure values for fast lookups:

  • 1 ATM = 14.696 PSI
  • 2 ATM = 29.392 PSI
  • 5 ATM = 73.480 PSI
  • 10 ATM = 146.96 PSI
  • 50 PSI ≈ 3.402 ATM
  • 100 PSI ≈ 6.805 ATM

Frequently Asked Questions

What is the exact conversion factor from PSI to ATM?

The conversion factor is 0.068046. Multiply any PSI value by this number to get atmospheres. This factor derives from the definition that 1 ATM equals 101,325 pascals and 1 PSI equals 6,894.76 pascals. For high-precision work, use 0.0680459968 or reference your field's specific standard.

Why is one atmosphere equal to 14.696 PSI?

Standard atmospheric pressure at sea level is defined as the weight of air pressing down on Earth's surface. This equals the pressure exerted by a 760 mm column of mercury (or 29.92 inches), which converts to approximately 14.696 PSI. This relationship underpins all pressure unit conversions.

Can I use this converter for gauge pressure readings?

Gauge pressure readings require caution. Most shop gauges (on air compressors, tire pressure monitors, and hydraulic systems) display gauge pressure, which is already corrected to zero at sea level. To convert to ATM, you must first add 14.696 PSI to the gauge reading, then apply the conversion factor. Always check your instrument's specification.

Are PSI and atmospheres used differently in science vs. engineering?

Physicists and chemists typically use atmospheres or pascals for consistency with SI units and published research. Engineers in North America favour PSI for historical and practical reasons—equipment, gauges, and technical drawings use it extensively. International engineering increasingly adopts SI, but PSI remains dominant in aerospace and industrial settings.

What is the difference between standard atmosphere (ATM) and technical atmosphere (at)?

A standard atmosphere (ATM) equals 101,325 pascals, the average sea-level air pressure. A technical atmosphere (at), less common, equals 98,066.5 Pa or 1 kgf/cm². They differ by about 3.3%, which matters in precise calculations but not for rough conversions. Always verify your source document's notation.

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