Pressure Unit Converter
MPa, kPa, bar, psi and kgf/cm² — every unit at once.
Quick answer
With the default inputs: Value 30 · From unit Megapascal · To unit Pound per square inchConverted value 4351.13 psi
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Result
Converted value
4351.13psi
| Megapascal (N/mm²) | 30MPa |
| Kilopascal | 30000.00kPa |
| Pascal | 30000000.00Pa |
| Bar | 300bar |
| Pound per square inch | 4351.13psi |
| Kilogram-force per cm² | 305.9149kgf/cm² |
| Atmosphere | 296.077atm |
| Metre of water | 3059.15mH₂O |
| Millimetre of mercury | 225019.13mmHg |
Conversions use 1 kgf = 9.80665 N. Design and test pressures for pipelines and pressure vessels must follow the design documents and current codes.
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Formula
| Base | 1 MPa = 1 N/mm² = 1000 kPa = 1 000 000 Pa |
| Old metric | 1 kgf/cm² = 0.0980665 MPa ≈ 0.1 MPa |
| Anglo-American | 1 psi = 6.89476 kPa, 1 bar = 100 kPa |
| Heads | 1 mH₂O = 9.80665 kPa, 1 atm = 10.33 mH₂O |
| Grade | C30 concrete = 30 MPa = 30 N/mm² = 300 kgf/cm² |
30 MPa is 300 kgf/cm², 4351.13 psi or 300 bar. A 1.0 MPa pipeline test equals 10.2 m of water head or 145.04 psi.
Pressure and strength unit reference
| Unit | Symbol | In MPa | Typical use |
|---|---|---|---|
| Megapascal | MPa | 1 | Concrete strength, design pressure |
| Kilopascal | kPa | 0.001 | Bearing capacity |
| Bar | bar | 0.1 | Imported plant, air pressure |
| Pound per square inch | psi | 0.006895 | US equipment |
| Kilogram-force per cm² | kgf/cm² | 0.09807 | Old drawings, water pressure |
| Metre of water | mH₂O | 0.009807 | Pump head |
| Atmosphere | atm | 0.101325 | Physical reference |
How to work it out
- Anchor on the basic relationship: 1 MPa = 1 N/mm² = 1000 kPa = 1,000,000 Pa. Concrete grade C30 means 30 MPa, which is 30 N/mm² — that identity should be automatic.
- Legacy engineering units: 1 kgf/cm² = 0.0980665 MPa, about 0.1 MPa. An old drawing specifying 300 kgf/cm² means roughly 29.4 MPa, close to today's C30.
- Anglo-American units: 1 psi = 6.89476 kPa ≈ 0.0069 MPa, and 1 bar = 100 kPa = 0.1 MPa. Air, hydraulic and tyre pressures use these.
- Liquid columns: 1 mH₂O = 9.80665 kPa, and 1 atm = 101.325 kPa = 10.33 mH₂O. Pump head and fire system pressures work in these.
- 1 mmHg = 133.322 Pa, used for vacuum and blood pressure — rare in construction but present in HVAC work.
- Check: 30 MPa is about 4350 psi or 306 kgf/cm². A wrong order means the wrong system.
Where it goes wrong
- Treating MPa and N/mm² as different units. They are identical, so a drawing in N/mm² needs no conversion.
- Equating kgf/cm² with MPa. The 2% gap is irrelevant at low pressure but at 30 MPa it is 0.6 MPa, enough to affect mix design.
- Mixing psi and bar. One bar is 14.5 psi, so a tyre at 2.5 bar is 36 psi — inflating to 2.5 psi leaves it flat.
- Confusing pump head with discharge pressure. Head is in metres of water and pressure in MPa, related by 1 MPa ≈ 102 m; they are not interchangeable.
- Using colloquial kilograms for concrete strength. Site talk of 300 kg means 300 kgf/cm², about 29.4 MPa, but some hear 300 MPa — which corrupts both pricing and acceptance.
Material and cost
In structures, a pressure unit error is a safety issue: reading C30 as 300 MPa produces a badly wrong mix, and remediation means demolition and rebuilding. In equipment selection, under-rating bursts pipework while over-rating wastes about 30% on materials.
On site
- Memorise the chain: 1 MPa ≈ 10 kgf/cm² ≈ 10 bar ≈ 145 psi ≈ 102 m of water. It covers about 90% of site situations.
- Old grade numbers map to modern classes at roughly ten times: C20 ≈ 200, C25 ≈ 250, C30 ≈ 300, C35 ≈ 350 kgf/cm².
- Pipe pressure ratings appear as PN: PN10 is 1.0 MPa and PN16 is 1.6 MPa. Allow about 1.5 times the working pressure when selecting.
- Fire systems are tested at 1.5 times working pressure and not below 1.4 MPa. Choose the gauge range accordingly — a 0-2.5 MPa gauge reads 1.4 MPa accurately.
Basis
- GB/T 3100-3102 Quantities and units series
- GB 50010-2010 (2015 edition) Code for design of concrete structures, concrete
- GB 50242-2002 Code for acceptance of construction quality of building water supply, drainage and heating works, indoor water supply
FAQ
Why is concrete strength in MPa when old drawings say “200 grade”?
“Grade 200” meant 200 kgf/cm², which is 19.6 MPa, today's C20. Old codes used grades in kgf/cm² and new ones use MPa classes; the conversion is not a simple divide by ten — C20 matches 200, C30 matches 300, C15 matches 150 — the factor is always 0.098.
How is pipeline test pressure set?
Water supply lines are tested at 1.5 times working pressure and not less than 0.6 MPa; fire mains at 1.5 times working pressure and not less than 1.4 MPa, never exceeding 1.5 times the nominal rating. Choose gauges whose range is 1.5-2 times the test pressure — an oversized gauge hides leaks in its reading error.
Is 1 bar the same as “one kilo of pressure”?
Site talk of “one kilo” means 1 kgf/cm² = 0.098 MPa while 1 bar is 0.1 MPa, 2% apart — fine as a rough equivalence. But nameplate values in bar, psi and MPa must be converted properly: in a high-rise, 2% is the difference between adequate and inadequate pressure on the top floor.
Cite this page
Use this format in reports, method statements or coursework. The link is permanent.
Building Calculator. Pressure Unit Converter. 2026-10-25. https://jianzhujisuan.com/en/unit-pressure
Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.