In process engineering, pressure measurement is critical for system safety and performance. The Megapascal (MPa) is the SI unit of pressure, defined as one million pascals (newtons per square meter). It is the standard unit used in international engineering specifications, particularly for structural materials and hydraulic systems.
The Pound per square inch (psi) is a non-SI unit derived from the avoirdupois system, commonly used in the United States and within the oil and gas industry. The relationship between these units is defined by the conversion factor: \(1 \text{ MPa} \approx 145.038 \text{ psi}\).
MPa Applications: Used in material yield strength, high-pressure vessel ratings, and international piping standards.
psi Applications: Used in pneumatic systems, tire pressure, and legacy industrial equipment specifications.
Megapascal to Pound per square inch Conversion Reference Table
Megapascal (MPa)
Pound per square inch (psi)
0.1
14.5038
0.5
72.5189
1.0
145.0377
2.0
290.0755
5.0
725.1887
10.0
1450.3774
20.0
2900.7549
50.0
7251.8872
100.0
14503.7744
500.0
72518.8719
1000.0
145037.7439
Conversion Example: 10 MPa to psi
To convert pressure from Megapascals to psi, multiply the value by the conversion factor of 145.03774389728312.
The factor 145.03774389728312 is derived from the exact definitions of the pound-force and the inch. Since 1 pascal is 1 newton per square meter, and 1 psi is 1 pound-force per square inch, the conversion relies on the international standard definitions of the pound (0.45359237 kg) and the inch (0.0254 m).
You should use MPa when working with international engineering standards (ISO), European material specifications, or scientific research. Use psi primarily when working with legacy US-based equipment or specific industry sectors like automotive or HVAC where psi remains the standard operating unit.
"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison." "Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house." — Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)