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Convert Kilopascals to Atmospheres - Pressure Converter

This converter translates a pressure value in kilopascals (kPa) to standard atmospheres (atm) using the internationally accepted fixed relationship between the units. Use it for quick unit changes in calculations, reports, instrumentation readouts, and engineering work.

Typical use cases include converting laboratory or instrument readouts, documenting test conditions, and preparing data for standards-based reports. Note the distinction between absolute and gauge pressures: this tool converts numeric units only and does not alter whether a value is absolute or gauge.

Updated Nov 10, 2025

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Methodology

The conversion uses the defined relationship where one standard atmosphere equals exactly 101325 pascals, which is 101.325 kilopascals. This definition is maintained by international standards bodies and physics reference authorities.

For measurement traceability and lab reporting, follow ISO/IEC 17025 for calibration and uncertainty statements. When reporting converted values in regulated contexts, include instrument calibration status and uncertainty per applicable standards.

Practical accuracy depends on the precision of the original measurement and the instrument calibration. For highest confidence, use calibrated reference equipment and document uncertainty according to ISO/IEC 17025 or equivalent national standards.

Worked examples

Example 1: Convert 202.65 kPa to atm. Calculation: 202.65 / 101.325 = 2.000 atm.

Example 2: Convert 50 kPa to atm. Calculation: 50 / 101.325 ≈ 0.493 atm.

Reverse example: Convert 1.5 atm to kPa. Calculation: 1.5 × 101.325 = 151.9875 kPa (report based on measurement precision).

Key takeaways

Use atm = kPa / 101.325 for kPa → atm and kPa = atm × 101.325 for atm → kPa. Report results with significance consistent with measurement uncertainty and calibration status.

Further resources

Expert Q&A

Is the standard atmosphere an exact value?

Yes. The standard atmosphere used for conversions is defined as exactly 101325 pascals (101.325 kPa). This is a defined reference unit rather than a measured property of Earth's atmosphere.

Does this conversion change absolute vs gauge pressure?

No. This tool only converts numeric units. If your measurement is gauge pressure (relative), convert units but retain the same reference. To convert between gauge and absolute you must add or subtract the local atmospheric pressure as applicable.

How many significant figures should I report?

Match the result to the input measurement's precision. If the input is from a calibrated instrument with stated uncertainty, propagate that uncertainty and round the converted value accordingly. For general use, three significant figures are common, but regulated reporting may require explicit uncertainty statements.

What standards apply to calibration and reporting?

Calibration and uncertainty reporting should follow ISO/IEC 17025 for testing and calibration laboratories. Use the SI and unit definitions published by national metrology institutes for traceability.

Can I use this converter for absolute and vacuum measurements?

Yes, the mathematical conversion applies to any numeric pressure value, including vacuum (positive magnitude reported relative to vacuum) or high pressures. Ensure you understand whether your input is absolute or gauge before converting and reporting.

Sources & citations