How do you convert hectopascals to atmospheres?

To convert hectopascals (hPa) to atmospheres (atm), multiply the pressure in hectopascals by 0.00098692 (atmospheres = hectopascals × 0.00098692).

What is 5 hectopascals in atmospheres?

5 hectopascals (5 hPa) is equal to 0.00493461 atmospheres (0.00493461 atm).

Which is larger, 1 hectopascal (hPa) or 1 standard atmosphere (atm)?

One standard atmosphere (atm) is larger than one hectopascal (hPa). Specifically, 1 atm equals 1,013.25 hPa, while 1 hPa is 0.00098692 atm.

How do I convert back from atmospheres (atm) to hectopascals (hPa)?

To reverse the calculation from atm to hPa, multiply your standard atmosphere value by the inverse factor 1,013.25 (or divide by 0.00098692). You can also click the Swap button in the tool above to flip directions in one click.

How many decimal places should I round hPa to atm results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 5 hPa ≈ 0.00 atm). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Hectopascals to Atmospheres Converter

Enter the pressure in hectopascals below to convert it to atmospheres.

Atmospheres to Hectopascals (atm → hPa)

Convert Hectopascals to Atmospheres

Enter a value in hectopascals (hPa) to convert to atmospheres (atm).

Value (hPa)

From

Result

•

0.004934616atmospheres

5 hPa = 0.004934616 atm

Result updates automatically

Get Widget

Equivalent Measurements Across UnitsFor 5 hPa

Pascals500 Pa

Kilopascals0.5 kPa

Bars0.005 bar

PSI0.07252 psi

Atmospheres0.00493461 atm

Suggested Conversions

Reference:NIST SP 811 (NIST SP 811 App. B.9 (Pressure & Stress))

[1–3] ↓

Hectopascal to Standard Atmosphere Conversion Table

Table showing various hectopascal measurements converted to atmospheres. Click any preset value or arrow to load it into the converter.

Hectopascals (hPa)	Atmospheres (atm)
1 hPa	0.000986923 atm
2 hPa	0.0019738 atm
2.5 hPa	0.0024673 atm
5 hPa	0.0049346 atm
10 hPa	0.0098692 atm
15 hPa	0.0148038 atm
20 hPa	0.0197385 atm
25 hPa	0.0246731 atm
30 hPa	0.0296077 atm
50 hPa	0.0493462 atm

How to Convert Hectopascals to Atmospheres

To convert hectopascals to atmospheres, multiply the pressure by the following conversion ratio: 0.000986923 atmospheres/hectopascal.

Since one hectopascal is equal to 0.000986923 atmospheres, you can use this simple formula to convert:

atmospheres = hectopascals × 0.000986923

The pressure in atmospheres is equal to the pressure in hectopascals multiplied by 0.000986923.

For example, here's how to convert 5 hectopascals to atmospheres using the formula above.

atmospheres = (5 hPa × 0.000986923) = 0.0049346 atm

How Many Atmospheres Are in a Hectopascal?

There are 0.000986923 atmospheres in a hectopascal, which is why we use this value in the formula above.

1 hPa = 0.000986923 atm|1 atm = 1,013.25 hPa

Our hectopascal to standard atmosphere calculator automatically converts your pressure measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

Hectopascals and atmospheres are both units used to measure pressure. Keep reading to learn more about each unit.

What Is a Hectopascal?

A hectopascal is a unit of pressure equal to 100 pascals (Pa), the base unit for pressure. Equal to 100 Pascals (identical to 1 millibar). [1]

The hectopascal is classified as a metric and SI-compatible unit of pressure. Hectopascals can be abbreviated as hPa; for example, 1 hectopascal can be written as 1 hPa.

In the metric system, "hecto" is the standard SI prefix for hundreds, or 10². This makes the hectopascal (hPa) a convenient decimal multiple of the pascal (Pa).

In practice, hectopascals (hPa) are widely used across standard pressure applications within SI metric workflows, engineering documentation, and technical data sheets.

Learn more about hectopascals in our Pressure Converter.

What Is a Standard Atmosphere?

A standard atmosphere is a unit of pressure equal to 101,325 pascals (Pa), the base unit for pressure. Standard sea-level atmospheric pressure defined as 101,325 Pascals. [2]

The standard atmosphere is classified as a standard unit of pressure. Atmospheres can be abbreviated as atm; for example, 1 standard atmosphere can be written as 1 atm.

When working with atmospheres (atm) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.

In practice, atmospheres (atm) are widely used across large-scale industrial, bulk, and macro-level pressure specifications within international standard workflows, engineering documentation, and technical data sheets.

Learn more about atmospheres in our Pressure Converter.

When converting pressure between hectopascals (hPa) and atmospheres (atm), keep full floating-point precision (1 hPa = 0.000986923 atm; 1 atm = 1,013.25 hPa) during intermediate calculations and round only the final standard atmosphere figure to match your instrument tolerance.

More Hectopascal & Standard Atmosphere Conversions

Need to calculate in the opposite direction? Use our atmospheres to hectopascals calculator to switch your starting unit immediately. You can also explore related tools such as converting atmospheres to hectopascals, converting bars to atmospheres, or converting torr to atmospheres.

Convert from Hectopascals

Convert to Atmospheres

Frequently Asked Questions

There are 0.00098692 atmospheres (atm) in 1 hectopascal (hPa). Conversely, 1 standard atmosphere (atm) is equal to 1,013.25 hectopascals (hPa).

Pressure Converter

Quick Info

Direct Factor: 1 hectopascal (hPa) equals 0.00098692 atmospheres (atm).
Inverse Factor: 1 standard atmosphere (atm) equals 1,013.25 hectopascals (hPa).
Formula: atmospheres = hectopascals × 0.00098692.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Hectopascal (hPa)

Equal to 100 Pascals (identical to 1 millibar).

Standard Atmosphere (atm)

Standard sea-level atmospheric pressure defined as 101,325 Pascals.

Pascal (Pa)

SI derived unit of pressure equal to 1 Newton per square meter (N/m²).

References

[1]NIST SP 811 · NIST SP 811 App. B.9 (Pressure & Stress)
Source
[2]NIST CUU · Derived SI Unit: Pascal (Pa)
Source
[3]BIPM · SI Brochure (9th Ed.) — Mechanics
Source

Related Categories

Add This Calculator to Your Site

Free HTML widget · 4 embed formats

Embed the interactive Hectopascals to Atmospheres converter on your blog, classroom, or documentation page.

Customize & Get Embed Code

References

NIST · BIPM · ISO

[1]
NIST SP 811 (NIST SP 811 App. B.9 (Pressure & Stress))·Pressure Metrology Standard — Hectopascals (hPa) to Atmospheres (atm)
NIST SP 811 Standard
[2]
NIST CUU (Derived SI Unit: Pascal (Pa))·Unit Specifications: Hectopascal (hPa) & Standard Atmosphere (atm)
NIST CUU Specification
[3]
BIPM (SI Brochure (9th Ed.) — Mechanics)·Conversion Factors & Mathematical Basis (hPa to atm)
BIPM Reference

Measurement Navigator78 Categories9 Scientific Domains

Browse All 78 Measurement Categories

A–Z Directory →Sitemap

Common ConvertersEveryday metric, imperial, and US customary converters for length, weight, volume, temperature, area, pressure, energy, speed, time, and data.