Calculation reviewed: 4 October 2026 · Engineering Desk Tools
How to use the Pressure unit converter calculator
Convert pressure between bar, psi, kPa and MPa without changing the pressure reference. Start with measurements or documented values for the equipment and reporting period you actually want to assess. The calculator does not fill in a typical installation for you. Its blank fields help keep a demonstration value from being mistaken for your own operating data.
Choose the required options, enter the values in the labelled units and select Calculate. If a field is rejected, check its range and unit before changing it. The result is accompanied by the equation and assumptions so you can decide whether it answers your engineering question.
Inputs and measurement basis
- Pressure value. The pressure value. Negative gauge values are accepted.
- From unit. The unit of the value you are entering.
- To unit. The unit you want the result in.
Record the measurement source and operating condition. Retain unrounded values for verification.
Method and interpretation
Unit conversion preserves the pressure reference. One bar gauge converted to psi remains gauge pressure, while one bar absolute remains absolute pressure. Gauge-to-absolute conversion needs the local atmospheric pressure as an additional input, which this converter intentionally does not assume.
Convert through kPa: 1 bar = 100 kPa; 1 MPa = 1000 kPa; 1 psi ≈ 6.894757 kPa.
Keep the same reference: gauge stays gauge and absolute stays absolute. Converting gauge to absolute also requires the local atmospheric pressure, which this tool does not add. Negative gauge values are accepted. The psi factor follows the rounded NIST table.
Worked example
This example does not populate the form. Enter your own installation data.
Calculated result: 14.5038 psi. Same pressure reference as your input
Check the arithmetic independently using the displayed equation. Retain intermediate precision and compare the final value with your equipment documentation.
Quick-reference table
These illustrative rows retain the worked example assumptions except for the varied input. They are not certified ratings or manufacturer data. Use the form for intermediate values.
Common mistakes
Confusing absolute and gauge values; using the same numerical pressure after changing the unit; overlooking negative gauge pressure on vacuum measurements. Before relying on the output, check the decimal format, unit scale and source of each value. Recheck unusual results against the formula.
Frequently asked questions
Are the example values used automatically?
No. Inputs remain blank when the tool opens or when you clear them. The worked example and table are reading material below the calculator. Enter the actual values you want to check each time, and label saved reports so their context is not lost.
What does the result mean?
The result is the same pressure in the selected unit, with the gauge or absolute reference unchanged.
Can I use a zero or a negative value?
The allowed range follows the meaning of each input. A divisor needs a positive value; other fields may allow zero. Negative gauge pressure is accepted. A rejected input must be corrected before a result can be shown.
Is this a final design or equipment approval?
No. Keep the same reference: gauge stays gauge and absolute stays absolute. Converting gauge to absolute also requires the local atmospheric pressure, which this tool does not add. Negative gauge values are accepted. The psi factor follows the rounded NIST table. Use the calculation as support for a checked decision, and review equipment documentation and applicable requirements before changing an installation or operating setting.
How can I save or share a calculation?
Calculate first, then use Copy result or Print report. Some maintenance tools also provide a CSV summary. Reports contain your own entered data, so review them before sharing. You can share the public page URL without including plant records or confidential measurements.
How do I report an unexpected result?
Use the Contact page and include the tool URL, input values, units, expected output and the reference you used. Explain the measurement basis. Exclude confidential information.
Related tools and records
Use related calculations with consistent units, periods and equipment scope.
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