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Convert Pascals to Atmospheres - Pressure Converter

This converter translates a pressure value in kilopascals (kPa) to standard atmospheres (atm) using the internationally recognized fixed relationship between the two units. It is intended for quick unit conversion and for preparing values for calculations or reporting.

The conversion uses the defined equivalence where one standard atmosphere is exactly 101.325 kilopascals. Results are mathematical conversions only and do not replace calibrated instrument measurements or uncertainty analysis required for compliance or scientific reporting.

For traceable measurements and instrument calibration follow recognized standards and laboratory accreditation procedures such as NIST traceability and ISO/IEC 17025. See the citations below for authoritative references.

Updated Nov 28, 2025

Interactive Converter

Convert between kilopascal and atmosphere with precision rounding.

Quick reference table

KilopascalAtmosphere
1 kPa0.0099 atm
5 kPa0.0493 atm
10 kPa0.0987 atm
25 kPa0.2467 atm
50 kPa0.4935 atm
100 kPa0.9869 atm

Methodology

The tool applies a fixed, exact mathematical factor linking the SI-derived pascal and the conventional unit 'standard atmosphere'. No empirical data, approximations, or temperature/altitude corrections are used; it is a pure unit conversion.

When converting measured pressures, consider the measurement uncertainty and device calibration state. For legally or safety-critical work, use instruments calibrated to standards traceable to national metrology institutes and follow ISO/IEC 17025 requirements for uncertainty reporting.

The converter provides a numeric conversion only. If you need to account for ambient variations (altitude, local gravity effects, or reference conditions), apply the appropriate physical models before or after unit conversion as required by the measurement context and relevant standards.

Worked examples

101.325 kPa → 101.325 ÷ 101.325 = 1.0 atm

50 kPa → 50 ÷ 101.325 ≈ 0.49345 atm (report per required significant figures or measurement uncertainty)

Further resources

Expert Q&A

Is this conversion exact or approximate?

The mathematical factor used (1 atm = 101.325 kPa) is a defined conventional equivalence. The computation is exact given that factor; practical measurement uncertainty arises from instruments and should be handled separately.

Should I adjust for altitude or temperature?

No. Unit conversion alone does not account for environmental effects. Adjust measured values for altitude, temperature, or reference conditions using appropriate physical models before reporting or converting if your workflow requires those corrections.

How many significant figures should I report?

Match the number of significant figures to the precision of your original measurement and include uncertainty per ISO/IEC 17025. For engineering estimates, three to five significant digits are common; for legal or lab reports, follow your calibration certificate guidance.

Can I use this for instrument calibration?

This converter is a calculation aid only. Calibration must be performed with calibrated standards traceable to a national metrology institute and documented per ISO/IEC 17025 and relevant national guidelines.

What is the difference between atm and bar?

One atmosphere (1 atm) equals 101.325 kPa, whereas one bar equals 100 kPa. Bar is a metric-derived unit commonly used in industry; atm is a conventional unit. Choose the unit that matches your domain standards and reporting requirements.

Where can I find authoritative references for unit definitions and calibration?

Refer to national metrology resources and international standards bodies such as NIST, ISO (including ISO 80000 for quantities and units and ISO/IEC 17025 for laboratory competence), and documentation from recognized standards organizations for calibration practices.

Sources & citations