Pounds Per Square Foot to Standard Atmospheres (psf to atm)
1 pound per square foot equals 0.000472541416 standard atmospheres (rounded).
How to convert pounds per square foot to standard atmospheres
To convert pounds per square foot to standard atmospheres, multiply the number of pounds per square foot by 0.000472541416. The factor is rounded to 10 significant digits. To go the other way, multiply standard atmospheres by 2,116.216624 (rounded).
standard atmospheres = pounds per square foot × 0.000472541416
Example: 10 pounds per square foot = 0.00472541416 standard atmospheres.
About these units
Pound Per Square Foot (psf)
About 47.88 pascals. Used in US structural engineering for distributed loads.
A square foot is 144 square inches, so one pound per square foot is one 144th of a psi, which comes to about 47.88 Pa; NIST gives 47.88026. The number is easy to picture: spread one pound-force evenly over a floor tile a foot across and that is the pressure, tiny compared with the 101,325 Pa of one standard atmosphere.
Building codes in the United States commonly state loads on floors and roofs this way, and snow and wind pressures are tabulated in the same unit. Metric countries use kilopascals or newtons per square metre instead, and 1 kPa is about 20.9 psf. Multiplying a psf figure by 144 gives psi, and by 47.88 gives pascals, so a 40 psf floor load is about 1.9 kPa.
1 pound per square foot = 47.88025898 pascals (approximately).
Sources: NIST SP 811, Appendix B.8; Wikipedia: Pounds per square inch
Standard Atmosphere (atm)
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
Related conversions
- Standard atmospheres to pounds per square foot (reverse)
- Pounds per square foot to pascals
- Pounds per square foot to kilopascals
- Pounds per square foot to bars
- Pounds per square foot to PSI
- Pascals to standard atmospheres
- Kilopascals to standard atmospheres
- Bars to standard atmospheres
- PSI to standard atmospheres
- Hectopascals to standard atmospheres
- Megapascals to standard atmospheres
- Millibars to standard atmospheres
- Torr to standard atmospheres
- Millimeters of mercury to standard atmospheres
- Inches of mercury to standard atmospheres
- Gigapascals to standard atmospheres
- Kilopounds per square inch to standard atmospheres
See all pressure units.