PSI to ATM Converter

Relationship Between PSI and Atmosphere

The conversion between pounds per square inch (PSI) and atmosphere (atm) is a fundamental pressure unit conversion between imperial and metric systems.

1 PSI = 0.068046 atm

Therefore,

1 atm = 14.6959 PSI

To convert PSI to atmosphere, we multiply the PSI value by 0.068046.

For example, 14.696 PSI equals approximately 1 atm, which is standard atmospheric pressure at sea level.

Quick Reference:
Standard atmospheric pressure is exactly 14.696 PSI or 1.000 atm at sea level. The atmosphere unit is commonly used in scientific, meteorological, and engineering applications, while PSI is predominantly used in the United States for commercial and industrial applications.

Pounds per Square Inch (PSI)

What is PSI?

PSI (pounds per square inch) is a unit of pressure in the imperial and US customary systems. It represents the force in pounds-force applied perpendicular to a surface area of one square inch. PSI is the most common pressure unit in the United States for commercial, industrial, and consumer applications.

Historical Background

PSI evolved from the British imperial system and became the standard pressure measurement in the United States and other countries using imperial units. Despite global metrication efforts, PSI remains deeply rooted in American engineering standards, manufacturing specifications, and everyday applications. The unit's widespread use in the US automotive and industrial sectors has made it a de facto international standard for certain applications.

Common Applications

• Automotive: Tire pressure (30-35 PSI cars, 50-80 PSI trucks, 30-40 PSI motorcycles)
• Hydraulics: Construction equipment (2,000-5,000 PSI), hydraulic brakes (1,000-2,000 PSI)
• Pneumatics: Air compressors (90-150 PSI), air tools (90 PSI), spray guns (40-60 PSI)
• Plumbing: Residential water pressure (40-80 PSI), municipal supply (50-100 PSI)
• Pressure Washing: Consumer (1,500-3,000 PSI), commercial (3,000-8,000 PSI)
• Scuba Diving: Compressed air tanks (3,000-4,500 PSI)
• Gas Systems: Natural gas lines (0.25-60 PSI), propane tanks (100-250 PSI)
• Industrial: Boilers (15-300 PSI), steam systems, compressed gas cylinders
• HVAC: Refrigerant systems (50-400 PSI depending on refrigerant type)
• Fire Safety: Fire extinguishers (100-200 PSI), sprinkler systems (7-30 PSI)

PSI Standards

In the United States, PSI is the legal standard for pressure gauges on consumer and industrial equipment. Most American technical specifications, safety standards (OSHA, ANSI), and equipment ratings are published in PSI. Understanding PSI to atmosphere conversion is essential for scientific calculations, high-altitude applications, and working with international standards.

PSIA, PSIG, and PSID

• PSIA (Absolute): Pressure measured relative to perfect vacuum. Used in scientific calculations and high-altitude applications.
• PSIG (Gauge): Pressure measured relative to atmospheric pressure. Most common in practical applications. A tire gauge reading 32 PSIG means 32 PSI above atmospheric pressure.
• PSID (Differential): Pressure difference between two points. Used in filter systems, flow measurements, and HVAC applications.
• Conversion: PSIA = PSIG + atmospheric pressure (~14.7 PSI at sea level)

Atmosphere (atm)

What is an Atmosphere?

The atmosphere (symbol: atm) is a unit of pressure defined as exactly 101,325 pascals (101.325 kPa). It represents the standard atmospheric pressure at sea level on Earth. The atmosphere is commonly used in scientific, meteorological, and engineering applications as a reference point for pressure measurements.

History and Definition

The atmosphere was originally defined based on the average atmospheric pressure at sea level. It has been standardized as exactly 101,325 Pa, which is approximately equal to the pressure exerted by a column of mercury 760 mm high at 0°C under standard gravity. 1 atm = 101,325 Pa = 101.325 kPa = 1.01325 bar.

Common Uses

• Scientific research: Standard reference pressure for experiments and calculations
• Meteorology: Atmospheric pressure measurements and weather forecasting
• Engineering: Pressure vessel ratings, hydraulic systems, and fluid dynamics
• Aviation: Altitude pressure calculations and aircraft systems
• Scuba diving: Depth pressure calculations (every 10 meters ≈ 1 atm additional pressure)
• Industrial processes: Vacuum systems, compression systems, and pressure testing
• Medical equipment: Hyperbaric chambers, respiratory systems
• Chemistry: Reaction conditions, gas law calculations
• Physics: Thermodynamics, fluid mechanics, and gas behavior studies
• Standards: Reference pressure for calibration and measurement standards

Standard Atmospheric Pressure

Standard atmospheric pressure is defined as exactly 101,325 Pa (101.325 kPa) at sea level at 15°C. This value is used as a reference point in many scientific and engineering calculations. Understanding the relationship between PSI and atmosphere is essential for working with pressure measurements in different unit systems and for scientific calculations involving atmospheric pressure.

PSI to Atmosphere Conversion Table

Common PSI to atmosphere conversions for reference: