KSI to PSI Conversion Calculator
Enter a pressure or stress value in kilopounds per square inch (ksi) and get the result in pounds per square inch (psi) plus five other common units instantly. Switch to reverse mode to convert psi back to ksi. The step panel shows the arithmetic so you can verify every figure.
Formula
Worked example
Convert 36 ksi (A36 structural steel yield point) to psi and MPa: 36 ksi x 1,000 = 36,000 psi. Then 36,000 psi x 6.894757 = 248,211 Pa = 248.2 MPa, which matches the 248 MPa figure in Eurocode 3.
What are ksi and psi?
Pounds per square inch (psi) is the standard unit of pressure and stress in the US customary system. It expresses the force in pounds-force acting on one square inch of area. Kilopounds per square inch (ksi) is simply a thousand times larger: 1 ksi = 1,000 psi. The "k" stands for kilo, the same metric prefix used in kilogram and kilometer. Because structural loads, material strengths, and hydraulic pressures in engineering often run into the thousands of psi, ksi is the preferred scale in US structural codes such as AISC, AASHTO, and ACI, just as megapascals (MPa) serve the same role in international SI-based codes.
How the ksi-to-psi conversion works
The conversion is a single multiplication by 1,000, or division by 1,000 in reverse. There are no temperature corrections, no density factors, and no approximations: the relationship is exact by the definition of the kilo prefix. For example, a bolt rated at 120 ksi proof load carries 120,000 psi. A concrete mix with a 28-day compressive strength of 4,000 psi is a 4 ksi mix. To go further into SI units, multiply psi by the NIST-defined factor 6,894.757 Pa/psi to reach Pascals, then divide by 1,000 for kPa, by 1,000,000 for MPa, or by 100,000 for bar.
Where ksi is used in practice
The ksi unit appears throughout North American structural and mechanical engineering. Steel design tables in AISC Steel Construction Manual list yield and tensile strengths in ksi (A36 = 36 ksi yield, A572 Grade 50 = 50 ksi). AASHTO bridge specifications give bolt proof loads and cable breaking strengths in ksi. Aerospace standards such as MIL-HDBK-5 use ksi for fatigue and ultimate loads of aluminum and titanium alloys. In geotechnical work, soil bearing pressures are sometimes reported in ksf (kips per square foot), but pile and anchor loads are quoted in kips and checked against member stresses in ksi. Wherever you see a US design code at the structural scale, ksi is almost certainly the working unit.
Converting ksi and psi to SI units (MPa and bar)
Most international engineering standards and research publications use megapascals (MPa) rather than ksi. The bridge between the two systems runs through the exact NIST conversion: 1 psi = 6,894.757 Pa. Therefore 1 ksi = 6,894,757 Pa = 6.895 MPa, and the quick rule of thumb is that 1 ksi is approximately 6.89 MPa. Conversely, 1 MPa is about 145 psi or 0.145 ksi. Bar is a non-SI unit still common in hydraulics and pneumatics: 1 bar = 100,000 Pa, so 1 ksi = 68.95 bar. This calculator shows all five conversions simultaneously so you can cross-check against any code or datasheet without a separate lookup.
Common engineering pressure and stress values
| Application | ksi | psi | MPa |
|---|---|---|---|
| Atmospheric pressure (standard) | 0.01470 | 14.696 | 0.101 |
| Concrete compressive strength (typical) | 3 to 6 | 3,000 to 6,000 | 20.7 to 41.4 |
| Structural steel yield (A36) | 36 | 36,000 | 248 |
| High-strength bolt (Grade 8) | 130 | 130,000 | 896 |
| Stainless steel 316 tensile strength | 70 to 95 | 70,000 to 95,000 | 483 to 655 |
| Aircraft-grade aluminum 7075 tensile | 83 | 83,000 | 572 |
| Carbon fiber composite tensile (axial) | 300 to 500 | 300,000 to 500,000 | 2,069 to 3,447 |
| Hydraulic cylinder working pressure | 1 to 5 | 1,000 to 5,000 | 6.9 to 34.5 |
Typical ksi values used in structural and mechanical engineering, with psi and MPa equivalents for quick reference.
Frequently asked questions
How do I convert ksi to psi?
Multiply the ksi value by 1,000. For example, 25 ksi = 25 x 1,000 = 25,000 psi. The conversion is exact: "ksi" literally means "kilo-psi", and kilo always means 1,000.
How do I convert psi to ksi?
Divide the psi value by 1,000. For example, 58,000 psi = 58,000 / 1,000 = 58 ksi. Switch this calculator to "PSI to KSI" mode to do this automatically and also see MPa, kPa, bar, and Pa.
What is 1 ksi in MPa?
1 ksi = 1,000 psi, and 1 psi = 6.894757 Pa, so 1 ksi = 6,894.757 Pa = 6.894757 MPa. The practical rule of thumb is 1 ksi is approximately 6.89 MPa, or conversely 1 MPa is roughly 0.145 ksi (145 psi).
Why do engineers use ksi instead of psi?
Because material strengths and structural stresses in everyday engineering are typically in the tens of thousands of psi. Writing 36,000 psi repeatedly is cumbersome, so codes like AISC and AASHTO standardized on ksi, making tables and calculations cleaner. It plays the same role that MPa plays in SI-based codes.
Is ksi used for pressure or stress, or both?
Both. Pressure and stress have the same physical dimensions (force per unit area), so ksi can describe either. In practice, ksi is most common for material stress (tensile strength, yield strength, fatigue limits) and for high-pressure hydraulic systems. Everyday gas pressures such as tire inflation are too small and are usually reported in psi rather than ksi.
What is 36 ksi in psi and MPa?
36 ksi = 36,000 psi = approximately 248.2 MPa. This is the standard yield strength of ASTM A36 structural steel, the most common grade used in building construction in the United States.
How do I convert ksi to bar?
1 ksi = 68.9476 bar. The path is: multiply ksi by 1,000 to get psi, multiply psi by 6,894.757 to get Pa, then divide by 100,000 to get bar. This calculator shows the bar result alongside psi, MPa, kPa, and Pa.