PSI to Pascal Converter
Common Conversions
| psi | Pa |
|---|---|
| 0.01 | 68.948 |
| 0.1 | 689.476 |
| 0.25 | 1723.69 |
| 0.5 | 3447.38 |
| 1 | 6894.76 |
| 2 | 13789.5 |
| 5 | 34473.8 |
| 10 | 68947.6 |
| 25 | 172369 |
| 50 | 344738 |
| 100 | 689476 |
| 1000 | 6894760 |
Why this conversion matters in chemistry
Pressure-vessel hydrotest math is a worked example. A 150 psi US-side hydrotest pressure becomes 1.034 MPa on the SI-side stress-analysis input for an ASME Section VIII Div 2 calculation, where every material-property correlation and every mesh-node stress output runs in pascals. The constant of 6894.76 Pa per psi comes from 1 psi = (1 lb × 4.4482 N/lb) / (1 in² × 645.16 mm²) = 6894.76 N/m². Mostly bookkeeping at the boundary of US-customary engineering specs and SI scientific calculations.
Formula
Where the factor comes from
Nothing is concealed on this pair — the pascal is a newton per square meter, so the factor is simply the psi written out in coherent SI. The trap is in the name. The pound of pounds per square inch is pound-force, a unit of force, while the identically spelled pound on a balance is a mass, and the two were tied together by decree rather than by physics: the international yard and pound agreement fixed the avoirdupois pound at exactly 0.45359237 kg and the inch at exactly 0.0254 m, with standard gravity already fixed at exactly 9.80665 m/s². That puts 4.4482216152605 N across 6.4516 × 10⁻⁴ m², or 6894.757293168… Pa. Every ingredient is a definition, so the factor carries no measurement uncertainty — only a decimal that never closes. The older engineering alternative, the poundal, left gravity out entirely and plays no part here.
Precision and significant figures
6894.76 is high by four parts in ten million and a blunt 6895 by thirty-five parts per million, both far beyond what any pressure instrument registers, so let the reading decide the figures. The live question on this pair is the size of the container instead. A pascal is a very small pressure, so ordinary bench values come out enormous: 100 psi is 689476 Pa, and printed that way a digit is easy to miscount. Anything above roughly 15 psi reads better in kilopascals, and above about 150 psi in megapascals, where a 5000 psi burst-test figure becomes a compact 34.5 MPa. Scientific notation works too, but a prefix survives spreadsheets and instrument entry fields better than an exponent does.
Worked Examples
Standard atmospheric pressure expressed in both unit systems.
The conversion anchor — useful for any quick scale check.
About a low-pressure compressed-gas reading.
About a high-pressure gas-cylinder regulator output.
Common mistakes
Pascals in PV = nRT demand cubic meters
Converting to pascals is usually done so R = 8.314 J/(mol·K) can be used, and that constant is coherent only with volume in cubic meters. Leave the volume in liters and the mole count lands a thousandfold high. A 250 mL vessel at 30 psi is 206843 Pa and 2.5 × 10⁻⁴ m³, not 0.25 — the unit conversion that matters most here is the one on the other variable.
MPa and Pa differ by a million
Pressure-vessel and material data sheets are written in megapascals, and 1 MPa is also exactly 1 N/mm², which is how mechanical specifications often print it. A converted 689476 Pa typed into a field expecting MPa is off by six orders of magnitude. Carry the prefix through the arithmetic rather than reattaching it at the end, where it is easy to lose count of zeros.
The pascal is also the unit of stress
Tensile strength, yield strength and elastic modulus are all quoted in psi in US mechanical literature and convert with this identical factor, but they are stresses, not fluid pressures. A modulus of 10⁷ psi becomes 6.89 × 10¹⁰ Pa quite correctly and means nothing in a gas-law calculation. Confirm what quantity a psi figure describes before the converted number goes anywhere near a thermodynamic equation.