Standard Atmospheres to Technical Atmospheres (atm to at)

1 standard atmosphere equals 1.033227453 technical atmospheres (rounded).

1 standard atmosphere = 1.033227453 technical atmospheres

How to convert standard atmospheres to technical atmospheres

To convert standard atmospheres to technical atmospheres, multiply the number of standard atmospheres by 1.033227453. The factor is rounded to 10 significant digits. To go the other way, multiply technical atmospheres by 0.9678411054 (rounded).

technical atmospheres = standard atmospheres × 1.033227453

Example: 10 standard atmospheres = 10.33227453 technical atmospheres.

About these units

Standard Atmosphere (atm)

Metric (SI)Current unit

Exactly 101,325 pascals, the average pressure of the atmosphere at sea level.

A column of mercury about 76 cm tall was Torricelli's measure of the air, and the standard atmosphere began as exactly that: the pressure of 760 mm of mercury at 0 degrees Celsius under standard gravity. It was used as a reference for physical and chemical properties, and the Celsius scale set 100 degrees as the boiling point of water at that pressure.

In 1954 the 10th CGPM confirmed the standard atmosphere as exactly 1,013,250 dynes per square centimeter, which is 101,325 pascals, a definition that no longer depends on the properties of any substance.

In practice one atmosphere is about 1.01325 bar, 760 mmHg, 14.696 psi or 29.92 inHg, and roughly the pressure of 10.33 meters of water. Chemistry splits on it: until 1982 standard temperature and pressure used 1 atm, but that year IUPAC recommended a standard pressure of exactly 100 kPa instead.

1 standard atmosphere = 101,325 pascals (exactly).

Sources: Wikipedia: Standard atmosphere (unit); Wikipedia: Atmospheric pressure; Wikipedia: Evangelista Torricelli

Technical Atmosphere (at)

CGS & old metricHistorical unit (no longer in standard use)

Exactly 98,066.5 pascals: one kilogram-force per square centimeter. Still seen on gauges in older equipment.

Pressure given as kilograms-force per square centimeter is the technical atmosphere, symbol at. It is fixed by arithmetic rather than by any air measurement: one kilogram-force is 9.80665 newtons and a square centimeter is one ten-thousandth of a square meter, so the unit is exactly 98,066.5 pascals, or 98.0665 kilopascals. Shop-floor shorthand includes kg/cm2, kp/cm2 and, in some older publications, ksc.

It is close to, but not the same as, other familiar pressures. It is about 0.981 bar, roughly 2 percent below a bar, and about 0.9678 of a standard atmosphere. In pounds per square inch it comes to about 14.22. The unit is deprecated and outside SI, yet it lingers because older pressure gauges and equipment, including Soviet-made instruments, are still in service with dials marked in kgf/cm2. NIST conversion tables list it with an exact factor to the pascal.

1 technical atmosphere = 98,066.5 pascals (exactly).

Sources: Wikipedia: Technical atmosphere; NIST SP 811, Appendix B.8 conversion factors; Wikipedia: Kilogram-force

Related conversions

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