PSIA to ATM
Convert psia into atmospheres for gauges, specs, hydraulic notes, and pressure reference checks.
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PSIA to ATM Table
| PSIA | Atmospheres |
|---|---|
| 1 | 0.0680459639 |
| 5 | 0.3402298196 |
| 10 | 0.6804596391 |
| 25 | 1.7011490978 |
| 50 | 3.4022981955 |
| 100 | 6.804596391 |
| 250 | 17.0114909775 |
| 500 | 34.022981955 |
| 1,000 | 68.04596391 |
| 2,500 | 170.114909775 |
Popular Conversions
- 1 psia = 0.0680459639 atmospheres
- 5 psia = 0.3402298196 atmospheres
- 10 psia = 0.6804596391 atmospheres
- 25 psia = 1.7011490978 atmospheres
- 50 psia = 3.4022981955 atmospheres
- 100 psia = 6.804596391 atmospheres
- 250 psia = 17.0114909775 atmospheres
- 500 psia = 34.022981955 atmospheres
What is PSIA and Atmosphere?
PSIA
Definition: PSIA means pounds per square inch absolute and includes atmospheric pressure in the reading.
History/origin: Absolute-pressure notation became important once engineers needed to distinguish total pressure from gauge-only readings.
Current use: PSIA is used in thermodynamics, compressor work, gas laws, and sealed-system analysis.
Atmosphere
Definition: An atmosphere is a pressure unit based on standard atmospheric pressure.
History/origin: It became a convenient reference pressure for chemistry, thermodynamics, and gas-law work.
Current use: Atmospheres are used in gas calculations, lab pressure notation, and process descriptions.
Related Pressure Conversions
Pressure values are commonly translated across SI, customary, and fluid-column units in the same job.
| Related Conversion | Factor or Rule | Formula |
|---|---|---|
| mmHg to kPa | × 0.133322387 | kPa = mmHg × 0.133322387 |
| MPa to psi | × 145.037738 | psi = MPa × 145.037738 |
| Pa to kPa | ÷ 1,000 | kPa = Pa ÷ 1,000 |
| Pa to psi | × 0.000145037738 | psi = Pa × 0.000145037738 |
| psi to bar | × 0.068947573 | bar = psi × 0.068947573 |
| psi to mmHg | × 51.714933 | mmHg = psi × 51.714933 |
| psia to psig | minus atmosphere | psig = psia – atmospheric pressure |
| psig to psia | plus atmosphere | psia = psig + atmospheric pressure |
Typical Use Cases
Frequently Asked Questions
Q: What is the difference between PSIG and PSIA?
A: PSIG is gauge pressure measured relative to atmospheric pressure, while PSIA is absolute pressure measured from a vacuum reference. That is why the two numbers are not interchangeable even before any other unit change is applied.
Q: What is a useful checkpoint for PSIA to ATM?
A: 1 psia equals 0.0680459639 atmospheres, which is a practical reference when checking a gauge reading against an absolute-pressure calculation.
Q: Why does atmospheric pressure matter on these pages?
A: Because one scale includes the surrounding atmospheric pressure and the other does not. The zero point is different, so the converted number changes accordingly.
Q: When do engineers need PSIG and PSIA conversions?
A: They come up in compressors, vacuum systems, thermodynamic calculations, pressure vessels, process equipment, and any worksheet that mixes gauge and absolute pressure.
Q: How do I convert Atmospheres back into PSIA?
A: psia = atm × 14.69594878. Use the reverse rule carefully so the gauge-versus-absolute reference stays consistent.
Q: Is this exact?
A: The calculation uses an exact factor.