Pounds-force per square inch to Standard atmospheres Calculator

Direct answer

Multiply the entered pounds-force per square inch value by 0.0680459639082161 to express it in standard atmospheres (atm). This converts pound-force per square inch (psi) to standard atmosphere (atm) within the documented pressure family.

Variables and formula

• Pounds-force per square inch (psi): the source value measured in pound-force per square inch.
• Standard atmospheres (atm): the same quantity expressed in standard atmosphere.
• Conversion factor: 0.0680459639082161 standard atmospheres per pound-force per square inch.

Standard atmospheres = Pounds-force per square inch × 0.0680459639082161

The generator emits numeric factors with at most 15 significant digits. Calculator results keep up to 10 significant digits for display; this formatting does not increase the precision of the measurement.

Unit definitions and named variants

Source unit: pound-force per square inch (psi). Psi in this family is pound-force per square international inch (lbf/in²). With standard gravity it is approximately 6894.75729316836 Pa. Named variant used: Pound-force per square inch using standard gravity; not pound-mass per square inch. Gauge versus absolute reference must be specified separately. Reference: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically; National Institute of Standards and Technology: NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement.

Target unit: standard atmosphere (atm). The standard atmosphere is defined as exactly 101,325 Pa. Named variant used: Standard atmosphere (atm); not technical atmosphere (at) or a measured local atmospheric pressure. Reference: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically.

The psi-to-atm direction remains inside the pressure quantity; it changes the unit label and numerical scale, not the kind of quantity being measured.

Relationship and precision

This route uses at least one deliberately preserved rounded factor. Treat the displayed factor as an approximation at the precision documented below.

• psi relationship: The preserved baseFactor 6894.757293 Pa is rounded from about 6894.75729316836 Pa, a difference of about 1.68×10⁻⁷ Pa per psi.
• atm relationship: The relationship to the pascal is exact.

To audit the factor through the family base unit, divide the raw dataset factors 6894.757293 by 101325. The generator emits that quotient once at 15 significant digits as the canonical direct factor 0.0680459639082161; runtime calculations do not divide the already-emitted base factors again.

Reproducible example

For 10 pounds-force per square inch, 10 × 0.0680459639082161 = 0.680459639082161 standard atmospheres. Repeating the same multiplication with the stated factor reproduces the displayed conversion before interface rounding.

Directional scale check

Because one pound-force per square inch contains 0.0680459639082161 standard atmospheres, the target number is smaller than the source number for every positive input. Zero maps to zero, while negative inputs are rejected because this family models non-negative magnitudes.

Interpretation

Read the result as standard atmospheres, not pounds-force per square inch. A value entered as psi leaves the calculator labelled atm; this directional distinction matters even when the two units describe the same pressure quantity.

Assumptions and limitations

• Only non-negative pressure magnitudes are accepted; negative gauge readings require a signed, reference-aware model.
• This family converts non-negative pressure magnitudes only. It does not add or subtract atmospheric reference pressure when changing between absolute, gauge, differential, or vacuum readings.
• Input and output must refer to the same pressure reference and measurement conditions; a unit conversion alone cannot change the reference datum.

Common mistakes

• Psi uses pound-force (lbf), not pound mass (lbm).
• The technical atmosphere (at) is based on kilogram-force per square centimeter and differs from atm.

Continue within the Pressure family

See the Pressure conversion hub for its five-unit reference table and all 20 directed routes.

• Reverse the direction: Standard atmospheres to Pounds-force per square inch
• Compare another pressure route: Pounds-force per square inch to Pascals
• Compare another pressure route: Pounds-force per square inch to Kilopascals
• Compare another pressure route: Pounds-force per square inch to Bar
• Compare another pressure route: Standard atmospheres to Pascals

Assumptions

• The entered value uses pounds-force per square inch exactly as labelled.
• Only non-negative pressure magnitudes are accepted; negative gauge readings require a signed, reference-aware model.
• Rounding and measurement uncertainty remain the user's responsibility.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically; National Institute of Standards and Technology; accessed Aug 7, 2026
• NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement; National Institute of Standards and Technology; accessed Aug 7, 2026