Femtopascal is 1e-15 pascal units.
Femtopascals to Atmospheres Converter — fPa to atm
Convert Femtopascal (fPa) to Atmosphere (atm) using the exact conversion factor (1 femtopascal = 9.869233e-21 atmosphere). See the formula, worked examples, conversion table, and common uses.
Femtopascals to Atmospheres converter
Converter
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mercury columns, water columns, and engineering pressure units.
Context values
Some unit families need one extra value for a physically accurate result.
A standard atmosphere is exactly 101,325 pascals.
Result = input x 1e-15 / 101325.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Femtopascals to Atmospheres
Femtopascal and Atmosphere both show up on pressure gauges — psi is standard on US tire and tool specifications, while bar is the everyday pressure unit across most of the rest of the world. Specifically: Femtopascal is 1e-15 pascal units, and a standard atmosphere is exactly 101,325 pascals.
Formula
atmospheres = femtopascals × 9.869233e-21
This factor comes from each unit's defined relationship to the category's base unit: 1 femtopascal equals 1e-15 base units, and 1 atmosphere equals 101325 base units, so dividing one by the other gives the direct femtopascal-to-atmosphere factor of 9.869233e-21.
Simple example
1 fPa × 9.869233e-21 = 9.869233e-21 atm
1 femtopascal = 9.869233e-21 atmospheres.
Real-world example
35 fPa × 9.869233e-21 = 3.454231e-19 atm
35 femtopascals = 3.454231e-19 atmospheres.
Conversion table
| Femtopascal (fPa) | Atmosphere (atm) |
|---|---|
| 1 fPa | 9.869233e-21 atm |
| 5 fPa | 4.934616e-20 atm |
| 10 fPa | 9.869233e-20 atm |
| 25 fPa | 2.467308e-19 atm |
| 50 fPa | 4.934616e-19 atm |
| 100 fPa | 9.869233e-19 atm |
Reverse conversion: Atmosphere to Femtopascal
9.869233e-21 atm × 1.01325e+20 = 1.000000034 fPa
9.869233e-21 atmospheres = 1.000000034 femtopascals.
femtopascals = atmospheres × 1.01325e+20
For a page dedicated to this direction, see Atmosphere to Femtopascal.
Understanding the Femtopascal (fPa)
Femtopascal is 1e-15 pascal units.
Understanding the Atmosphere
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
Where it's used: Widely used internationally in chemistry, meteorology, and diving/aviation contexts alongside the pascal and bar
Uses of the Atmosphere today
- Chemistry (standard conditions are often defined at 1 atm)
- Diving and aviation pressure references
- General reference for everyday atmospheric pressure
Atmosphere — sources
- BIPM SI Brochure — Standard atmosphere listed among non-SI units with a fixed exact value in pascals.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many atmospheres are in 1 femtopascal?
1 femtopascal equals 9.869233e-21 atmospheres, using the exact defined conversion factor rather than an estimate.
How do I convert femtopascal to atmosphere?
Multiply the femtopascal value by 9.869233e-21. The converter above does this instantly to whatever precision you set.
How do I convert atmosphere back to femtopascal?
Use the reverse factor: 1 atmosphere equals 1.01325e+20 femtopascals. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtopascal?
Femtopascal (fPa) is a unit of pressure.
What is a atmosphere?
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
Is the femtopascal to atmosphere conversion exact?
Yes. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.