Calculator input form
The page uses a single-column layout, while the input fields switch between three, two, and one columns by screen size.
Example data table
These examples show typical outputs. The absolute input example assumes standard atmospheric pressure of 14.6959 psi.
| Input Bar | Input Type | PSIG Output | PSIA Output | Notes |
|---|---|---|---|---|
| 1.000 | Gauge | 14.504 | 29.200 | Simple direct gauge conversion. |
| 5.000 | Gauge | 72.519 | 87.215 | Useful for compressor and line checks. |
| 10.000 | Gauge | 145.038 | 159.734 | Common for industrial pressure references. |
| 2.000 | Absolute | 14.312 | 29.008 | Atmospheric pressure subtracted for PSIG. |
Formula used
- Gauge pressure measures pressure above the surrounding atmosphere.
- Absolute pressure includes atmospheric pressure in the reading.
- Why the input type matters: the same bar number gives different PSIG values when the source is absolute instead of gauge.
- Engineering reminder: always confirm whether documents list pressure as bar(g) or bar(a) before converting.
How to use this calculator
- Enter the pressure value in bar.
- Choose whether that bar value is gauge or absolute.
- Keep the atmospheric reference as default, or replace it with your local or test reference.
- Set decimal places for the output and fill the range fields if you want a conversion table.
- Optionally enter a safety limit in PSIG for a pass or fail comparison.
- Press Convert and Build Report to show the result above the form, generate the table, and draw the Plotly graph.
Frequently asked questions
1) What is the difference between bar and PSIG?
Bar is a metric pressure unit. PSIG is pounds per square inch gauge, which means pressure measured above atmospheric pressure. This calculator converts the entered bar value into a gauge-pressure result and can also handle bar absolute inputs.
2) Why does bar absolute need atmospheric pressure?
Absolute pressure already includes atmospheric pressure. To get a gauge reading, atmospheric pressure must be subtracted. That is why the calculator asks for an atmospheric reference when you choose bar absolute as the input type.
3) When should I choose bar gauge?
Choose bar gauge when your instrument, manual, or pressure transmitter reports pressure above ambient air. In that case, the conversion is direct because both bar(g) and PSIG are gauge-based measurements.
4) Can PSIG be negative?
Yes. A negative PSIG value means the pressure is below atmospheric pressure. This often appears in vacuum service, suction lines, sealed vessels during cooldown, or systems referenced against ambient conditions.
5) Why include a safety limit field?
It helps compare the converted result to a target threshold. This is useful for maintenance checks, pressure-test planning, operating envelopes, and quick pass or fail review during reporting.
6) What does the generated table do?
The table converts a full pressure range instead of only one value. That makes it useful for calibration sheets, engineering notes, commissioning records, and operator reference charts.
7) Why is a graph helpful for pressure conversion?
The graph shows how PSIG changes across the selected bar range. It makes trends easier to read, helps validate step-based tables, and improves presentation when sharing conversion results with teams.
8) Can I use this page for reports?
Yes. The calculator includes CSV and PDF export options, a conversion table, formulas, and a chart. That makes the page suitable for documentation, quick field use, and printable review.