Hectopascal is 100 pascal units.
Hectopascals to Attopascals Converter — hPa to aPa
Convert Hectopascal (hPa) to Attopascal (aPa) using the exact conversion factor (1 hectopascal = 1e+20 attopascal). See the formula, worked examples, and conversion table.
Hectopascals to Attopascals converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Attopascal is 1e-18 pascal units.
Result = input x 100 / 1e-18.
Stress Pressure units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Hectopascals to Attopascals
Hectopascal and Attopascal both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Hectopascal is 100 pascal units, and attopascal is 1e-18 pascal units.
Formula
attopascals = hectopascals × 1e+20
This factor comes from each unit's defined relationship to the category's base unit: 1 hectopascal equals 100 base units, and 1 attopascal equals 1e-18 base units, so dividing one by the other gives the direct hectopascal-to-attopascal factor of 1e+20.
Simple example
1 hPa × 1e+20 = 1e+20 aPa
1 hectopascal = 1e+20 attopascals.
Real-world example
100 hPa × 1e+20 = 1e+22 aPa
100 hectopascals = 1e+22 attopascals.
Conversion table
| Hectopascal (hPa) | Attopascal (aPa) |
|---|---|
| 1 hPa | 1e+20 aPa |
| 10 hPa | 1e+21 aPa |
| 50 hPa | 5e+21 aPa |
| 100 hPa | 1e+22 aPa |
| 500 hPa | 5e+22 aPa |
| 1,000 hPa | 1e+23 aPa |
Reverse conversion: Attopascal to Hectopascal
1e+20 aPa × 1e-20 = 1 hPa
1e+20 attopascals = 1 hectopascals.
hectopascals = attopascals × 1e-20
For a page dedicated to this direction, see Attopascal to Hectopascal.
Understanding the Hectopascal (hPa)
Hectopascal is 100 pascal units.
Understanding the Attopascal (aPa)
Attopascal is 1e-18 pascal units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many attopascals are in 1 hectopascal?
1 hectopascal equals 1e+20 attopascals, using the exact defined conversion factor rather than an estimate.
How do I convert hectopascal to attopascal?
Multiply the hectopascal value by 1e+20. The converter above does this instantly to whatever precision you set.
How do I convert attopascal back to hectopascal?
Use the reverse factor: 1 attopascal equals 1e-20 hectopascals. You can also use the swap control in the converter above to flip the direction instantly.
What is a hectopascal?
Hectopascal (hPa) is a unit of engineering.
What is a attopascal?
Attopascal (aPa) is a unit of engineering.
Is the hectopascal to attopascal conversion exact?
Yes. Both hectopascal and attopascal are defined by fixed standards rather than physical artifacts, so the factor of 1e+20 used above is exact to as many digits as you choose to display.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.