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
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.
Attopascal is 1e-18 pascal units.
Result = input x 100 / 1e-18.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Hectopascals to Attopascals
Hectopascal and Attopascal 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: 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
35 hPa × 1e+20 = 3.5e+21 aPa
35 hectopascals = 3.5e+21 attopascals.
Conversion table
| Hectopascal (hPa) | Attopascal (aPa) |
|---|---|
| 1 hPa | 1e+20 aPa |
| 5 hPa | 5e+20 aPa |
| 10 hPa | 1e+21 aPa |
| 25 hPa | 2.5e+21 aPa |
| 50 hPa | 5e+21 aPa |
| 100 hPa | 1e+22 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 pressure.
What is a attopascal?
Attopascal (aPa) is a unit of pressure.
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.