What this calculator does
Ksi (kilopound per square inch) and MPa (megapascal) are both units of stress or pressure, and both turn up constantly in materials engineering: a steel datasheet quoting a yield strength in ksi, a design code specifying an allowable stress in MPa, or a supplier certificate that uses whichever unit its home country prefers. This calculator converts ksi to MPa or MPa to ksi in either direction, so a figure from one system can be checked against a spec written in the other.
The conversion is a fixed multiplication, not something that changes with material or temperature: 1 ksi equals exactly 1,000 psi, and 1 psi equals 6.89476 kilopascals, which gives 1 ksi = 6.89476 MPa. The tool also shows the equivalent value in plain psi, since ksi is really just psi expressed in thousands.
The formula
Multiply a ksi value by 6.89476 to get megapascals. To go the other way, divide the MPa value by the same 6.89476. Both directions use the identical factor, since it comes directly from the definition of the pound-force per square inch in SI units, not from an approximation.
| Term | Meaning |
|---|---|
| ksi | Kilopound per square inch: 1,000 pounds-force per square inch, a common unit for tensile and yield strength in US engineering. |
| MPa | Megapascal: one million pascals, the SI unit most structural and materials codes outside the US use for stress. |
| psi | Pound per square inch, the base unit that ksi is a multiple of: 1 ksi = 1,000 psi. |
The inputs explained
| Field | What to enter |
|---|---|
| Direction | Choose whether you are converting a ksi figure into MPa, or a MPa figure into ksi. |
| Value | The stress or pressure value to convert, in whichever unit you selected above. |
When to use it
Checking a material datasheet
US steel and aluminium suppliers often quote yield and tensile strength in ksi, while a project specification or design code written to a metric standard wants MPa. Converting the datasheet figure confirms it actually meets the specified value before it is signed off.
Comparing standards across countries
A component sourced from a supplier working in ksi needs to be checked against a local building or pressure-vessel code written in MPa, or vice versa, and a small rounding slip in that conversion can make a safe design look marginal or a marginal one look safe.
Converting pressure ratings
Ksi and MPa are also used for pressure ratings on cylinders, hydraulic systems and test equipment, not only for material strength, so the same conversion applies whenever a rating sheet uses one unit and the working documentation uses the other.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Common ksi values converted to MPa
Yield and tensile strength figures often seen on steel and aluminium datasheets, converted to MPa.
| ksi | Value in MPa | Value in psi |
|---|---|---|
| 10 ksi | 68.95 MPa | 10,000 psi |
| 20 ksi | 137.90 MPa | 20,000 psi |
| 36 ksi | 248.21 MPa | 36,000 psi |
| 50 ksi | 344.74 MPa | 50,000 psi |
| 60 ksi | 413.69 MPa | 60,000 psi |
| 80 ksi | 551.58 MPa | 80,000 psi |
| 100 ksi | 689.48 MPa | 100,000 psi |
Common MPa values converted to ksi
Round MPa figures, as they might appear on a metric spec sheet, converted back to ksi.
| MPa | Value in ksi | Value in psi |
|---|---|---|
| 50 MPa | 7.252 ksi | 7,252 psi |
| 100 MPa | 14.504 ksi | 14,504 psi |
| 150 MPa | 21.756 ksi | 21,756 psi |
| 200 MPa | 29.008 ksi | 29,008 psi |
| 250 MPa | 36.259 ksi | 36,259 psi |
| 400 MPa | 58.015 ksi | 58,015 psi |
| 500 MPa | 72.519 ksi | 72,519 psi |
Questions
What is the exact ksi to MPa conversion factor?
1 ksi equals 6.89476 MPa. It follows from the definition of the pound-force per square inch in SI units, not from a rounded approximation, so it applies exactly regardless of the value being converted.
Is ksi the same as psi?
No, but they are directly related: ksi means kilopound per square inch, so 1 ksi equals exactly 1,000 psi. A yield strength of 36 ksi is the same as 36,000 psi.
Why do US and metric material standards use different units?
The US customary system for engineering stress developed around pounds and square inches, while most of the rest of the world standardised on SI pascals. Ksi and MPa persist side by side because older US codes, supplier certificates and metric design standards are all still in active use.
Does this conversion apply to pressure as well as stress?
Yes. Ksi and MPa are both units of force per unit area, so the same 6.89476 factor converts a pressure rating just as it converts a material stress figure. The physical quantity being measured does not change the arithmetic.
For everyday pressure units such as bar, psi and atmospheres, see the pressure converter. For tyre pressures specifically, use the kPa to PSI tyre pressure converter.