How to Convert Pascals to Atmospheres (Pa to atm)
Pressure conversions are used for tyre pressure (psi or bar), blood pressure readings in mmHg and weather maps in millibars. This guide shows how to convert pascals into atmospheres by hand, with examples and a quick-reference table.
The conversion
To convert pascals to atmospheres, multiply the value by 9.869233e-06. To go the other way, divide by the same number (or multiply by 101,325). Because the factor is tiny, scientific notation keeps the numbers manageable.
Atmospheres = pascals × 9.869233e-06
Worked examples
- 3 Pa = 2.960770e-5 atm
- 12.5 Pa = 0.000123 atm
- 75 Pa = 0.00074 atm
Pascals to Atmospheres table
| Pascals | Atmospheres |
|---|---|
| 1 Pa | 9.869233e-6 atm |
| 2 Pa | 1.973847e-5 atm |
| 5 Pa | 4.934616e-5 atm |
| 10 Pa | 9.869233e-5 atm |
| 20 Pa | 0.000197 atm |
| 25 Pa | 0.000247 atm |
| 50 Pa | 0.000493 atm |
| 100 Pa | 0.000987 atm |
| 250 Pa | 0.002467 atm |
| 500 Pa | 0.004935 atm |
| 1,000 Pa | 0.009869 atm |
Common questions
Is Pa to atm exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Atmospheres to Pascals converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Pascals to Atmospheres Converter or browse all pressure converters.
Run your own numbers: Pascals to Atmospheres Converter