MPa to PSI Converter

Pressure rating conversion between metric (MPa) and US customary (psi) systems for hydraulic equipment, process piping, and pressure vessel specification.

Hydraulic systems in injection molding machines, press brakes, mobile construction equipment (excavators, loaders, bulldozers from Caterpillar, Komatsu, Liebherr), and aerospace ground support equipment are rated in MPa in their European OEM literature and psi in their American marketing — a Bosch Rexroth A10VSO pump rated at 28 MPa (4,061 psi) maximum pressure is the same physical unit as a Parker P1 pump rated at 4,000 psi maximum.

Engineering teams specifying hydraulic power units for international projects must carry out this conversion at the equipment selection boundary and ensure that the relief valve setting (commonly 1.1× the working pressure) is correctly translated on both the schematic and the nameplate.

Pressure vessel code calculations per ASME Section VIII (Division 1 or 2) in the US and PD 5500 / EN 13445 in Europe are typically expressed in MPa for the international codes — a vessel designed for 5 MPa (725 psi) at 200°C requires identical allowable stress calculations but the value carried through the calc sheet switches between units depending on the engineer.

Hydrostatic testing of pressure vessels, piping, and gas cylinders universally uses a test pressure expressed as 1.3× to 1.5× the design pressure, and the test pressure in MPa for an international project must be converted to psi for the US inspector witnessing the test (and vice versa).

Safety instrumented systems per IEC 61511 specify set pressures for safety valves, rupture discs, and pressure transmitters in bar, MPa, or kPa depending on the regional market — the safety integrity level (SIL) calculation does not change with units, but the documentation must carry the correct numerical value in the local convention.

Hydraulic cylinder bore and rod calculations (force = pressure × area) require consistent units throughout — if the area is computed in in² (US) but the pressure comes from a European schematic in MPa, the force result is off by a factor of 6894.76 (the conversion from Pa to psi), a common cause of undersized cylinder selection on international projects.

Diving and hyperbaric chamber operations use bar (and occasionally MPa) in most of the world and psi in the US Navy / NOAA diving manuals — a surface-supplied diving operation at 30 meters seawater (about 4 bar, 0.4 MPa, 58 psi) must be communicated to a US diving supervisor in psi for bell runs and decompression table entry.

Hydrogen refueling stations for fuel cell vehicles are specified at 350 bar (35 MPa, ~5,075 psi) and 700 bar (70 MPa, ~10,150 psi) per SAE J2601 and ISO 17268; the conversion appears in every component datasheet and certification test report for nozzles, hoses, and storage vessels.