Pounds per square inch.
PSI to KSI Converter — psi to ksi
Convert PSI (psi) to KSI (ksi) using the exact conversion factor (1 psi = 0.001 ksi). See the formula, worked examples, conversion table, history, and common uses.
PSI to KSI converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Kips per square inch.
Result = input x 6894.757293 / 6.89475729e+6.
Stress Pressure units are compatible.
Reserved above the conversion cards and below the converter.
About Converting PSI to KSI
PSI and KSI both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. PSI is most often used for tire pressure specifications in the us.
Formula
ksi = psi × 0.001
This factor comes from each unit's defined relationship to the category's base unit: 1 psi equals 6894.75729317 base units, and 1 ksi equals 6894757.29317 base units, so dividing one by the other gives the direct psi-to-ksi factor of 0.001.
Simple example
1 psi × 0.001 = 0.001 ksi
1 psi = 0.001 ksi.
Real-world example
100 psi × 0.001 = 0.1 ksi
100 psi = 0.1 ksi.
Conversion table
| PSI (psi) | KSI (ksi) |
|---|---|
| 1 psi | 0.001 ksi |
| 10 psi | 0.01 ksi |
| 50 psi | 0.05 ksi |
| 100 psi | 0.1 ksi |
| 500 psi | 0.5 ksi |
| 1,000 psi | 1 ksi |
Reverse conversion: KSI to PSI
0.001 ksi × 1000 = 1 psi
0.001 ksi = 1 psi.
psi = ksi × 1000
For a page dedicated to this direction, see KSI to PSI.
Understanding the PSI
PSI (psi) measures pressure. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. It is classified as a US/imperial customary unit.
Where it's used: United States (standard pressure unit for tires, tools, and plumbing)
Uses of the PSI today
- Tire pressure specifications in the US
- Hydraulic and pneumatic system ratings
- Plumbing, compressed-air tools, and industrial equipment ratings
History of the PSI
PSI is a derived unit from the pound-force and the inch, both themselves standardized through English and later international agreements rather than invented as a pressure unit from scratch.
It became the default pressure unit in US engineering as pound-force and inch-based measurement dominated American industry through the 19th and 20th centuries, and it remains in everyday use for tires and tools even as most other measurements in the US context stay imperial.
Historical origin. PSI was not the invention of a single named person; it developed through the process described above.
Understanding the KSI (ksi)
Kips per square inch.
PSI — sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units — Documents conversion factors for psi and other US customary pressure units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many ksi are in 1 psi?
1 psi equals 0.001 ksi, using the exact defined conversion factor rather than an estimate.
How do I convert psi to ksi?
Multiply the psi value by 0.001. The converter above does this instantly to whatever precision you set.
How do I convert ksi back to psi?
Use the reverse factor: 1 ksi equals 1,000 psi. You can also use the swap control in the converter above to flip the direction instantly.
What is a psi?
PSI (psi) measures pressure. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. It is classified as a US/imperial customary unit.
What is a ksi?
KSI (ksi) is a unit of engineering.
Is the psi to ksi conversion exact?
Yes. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the psi still used today?
United States (standard pressure unit for tires, tools, and plumbing)
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.