Megapascal to PSI Converter
1 MPa = 145.0377 psi. Type in either box.
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A megapascal is about 145 psi
Megapascals are how the metric world states material strength and hydraulic pressure; psi is how the American one does. Converting between them is routine in any project where the steel comes from one place and the specification from another.
1 MPa = 145.0377 psi
Two anchors make the numbers easy to judge. One megapascal is roughly ten atmospheres, and roughly 145 psi. So structural concrete at 30 MPa is about 4,350 psi, and mild steel yielding at 250 MPa is about 36,000 psi.
The megapascal
A million pascals, used where pressures and stresses are large: hydraulics, material strength, concrete. One megapascal is almost exactly ten atmospheres, which makes it a convenient size for engineering.
A megapascal is also identical to a newton per square millimetre, which is why materials datasheets quote tensile strength in MPa and structural drawings in N/mm² without anyone needing to convert.
Pounds per square inch
PSI is one pound of force spread over one square inch. It is the everyday pressure unit in the United States and still widely used in Britain for tyres, and it is defined exactly, because both the pound-force and the inch are defined exactly.
Almost every psi figure you meet in daily life is gauge pressure — pressure above atmospheric, sometimes written psig. A tyre at 32 psi holds 32 psi more than the air around it, not 32 psi in total.
The working, step by step
Every line updates with whatever you type above. The point is the method, which is the same for any pair of units in this family.
The same quantity, two different numbers
One physical amount, read off two scales. The tick marks do not line up, and the gap between them is the conversion factor made visible.
How much is that?
A number is easier to judge next to something familiar.
Your turn
Reading a method and being able to use it are different things. Answer within half a per cent and it counts as correct.
Score: 0 of 0
How to use this converter
- Type into either box. The other side updates as you go; there is no button to press.
- Swap the direction with the button between the boxes, carrying your value across.
- Set the decimals if the default is more or less precision than you need.
- Copy the answer with its unit, ready to paste.
- Use the shortcut buttons for the values that come up most often.
- Share the result. The address bar tracks what you type, so the link you copy opens on the same number.
Common uses and tips
Where pressure conversions come up
- Tyres. The single most common reason anyone converts pressure. American placards are in psi, European and Asian ones in bar or kPa, and the three appear side by side on the same door sticker.
- Weather. Forecasts use hectopascals or millibars, which are the same size — 1 hPa is 1 mbar. A typical high-pressure system reads about 1020 of either.
- Diving. Cylinder pressures are in bar almost everywhere and psi in the United States. A full 200 bar cylinder is about 2,900 psi.
- Coffee. Espresso machines are specified in bar; nine bar at the group head is the usual target, which is about 130 psi.
- Materials and hydraulics. Tensile strength and hydraulic ratings come in MPa or psi, and the two communities rarely use the same one.
The trap: gauge pressure and absolute pressure
Almost every pressure you read off a dial in daily life is gauge pressure — how much higher than the surrounding air it is. A tyre at 32 psi contains 32 psi more than the atmosphere, so its absolute pressure is about 46.7 psi.
Conversion between units never changes which of the two you have. If you start with a gauge reading you end with a gauge reading. Where it goes wrong is in physics and chemistry, where the gas laws need absolute pressure: add one atmosphere to a gauge figure before it goes into a calculation. The units psig and psia exist precisely to keep the two apart.
Tips worth knowing
- One bar is not one atmosphere. It is 0.9869 of one. The difference is small enough to ignore for a tyre and large enough to matter in a laboratory.
- Millibars and hectopascals are identical. Weather maps use whichever the local service prefers; the number is the same.
- One MPa is about ten atmospheres, which makes megapascals easy to sanity-check against everyday pressures.
- Torr and mmHg are interchangeable in practice, differing by about one part in seven million.
Values people look up most
Each one opens the converter with the number already in it.
- 0.5 MPa to psi
- 1 MPa to psi
- 2 MPa to psi
- 5 MPa to psi
- 10 MPa to psi
- 15 MPa to psi
- 20 MPa to psi
- 25 MPa to psi
- 30 MPa to psi
- 35 MPa to psi
- 40 MPa to psi
- 50 MPa to psi
- 60 MPa to psi
- 100 MPa to psi
- 150 MPa to psi
- 200 MPa to psi
- 250 MPa to psi
- 300 MPa to psi
- 400 MPa to psi
- 500 MPa to psi
Quick reference
| Megapascals | PSI |
|---|---|
| 1 MPa | 145.037738 psi |
| 5 MPa | 725.188689 psi |
| 10 MPa | 1,450.377377 psi |
| 20 MPa | 2,900.754755 psi |
| 25 MPa | 3,625.943443 psi |
| 30 MPa | 4,351.132132 psi |
| 40 MPa | 5,801.509509 psi |
| 50 MPa | 7,251.886887 psi |
| 100 MPa | 14,503.773773 psi |
| 250 MPa | 36,259.434433 psi |
| 400 MPa | 58,015.095092 psi |
| 500 MPa | 72,518.868865 psi |
Questions people ask
What is the formula for MPa to psi?
Multiply by 145.0377.
What is 30 MPa in psi?
4,351 psi — a typical structural concrete strength.
Why do materials datasheets use MPa?
Because a megapascal equals one newton per square millimetre, which matches the millimetre dimensions used on engineering drawings.
Does this convert gauge or absolute pressure?
Whichever you put in. Converting units does not change which kind of pressure you have — a gauge reading converts to a gauge reading. If a calculation needs absolute pressure, add one atmosphere first.