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The specified compressive strength in PSI.
US residential slabs are commonly specified at 3,000 to 4,000 psi. This is the 28-day cylinder strength unless the specification says otherwise.
Compressive strength
27.58 MPa
1 psi = 6,894.757 Pa, so 1,000 psi = 6.895 MPa. Cube and cylinder strengths differ by roughly 20% for the same concrete — the unit conversion does not reconcile the test method.
- Conversion factor applied
- 0.01 MPa per psi
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Concrete PSI to MPa Calculator: 27.58 MPa — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- 1 psi = 6,894.757293 Pa exactly, so 1 MPa = 145.038 psi
- Concrete compressive strength is conventionally the 28-day value; US testing uses cylinders, much of Europe uses cubes
Inputs used
- Compressive strength (psi)
- 4000
Intermediate steps
- Conversion factor applied
- 0.01 MPa per psi
Confidence note: 1 psi = 6,894.757 Pa, so 1,000 psi = 6.895 MPa. Cube and cylinder strengths differ by roughly 20% for the same concrete — the unit conversion does not reconcile the test method.
What this calculation does not cover
- The arithmetic is exact; the specifications are not interchangeable. A 4,000 psi mix is not the same specification as C25/30 — the two systems test different specimens at different ages and state strength differently, so converting the number does not convert the requirement.
- Cylinder and cube strengths differ. North American practice tests cylinders and European practice tests cubes, and a cube reads roughly 20% higher than a cylinder of the same concrete. A converted figure compared against the wrong specimen type is wrong by about that much.
- Specified strength is not the strength to design a mix for. Target mean strength adds a margin for the plant's standard deviation, which is the whole subject of ACI 211 and is not in this conversion.
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This result is a specification — 27.58 MPa — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0
Regulatory standards & verification citations2
- 1 psi = 6,894.757293 Pa exactly, so 1 MPa = 145.038 psi
- Concrete compressive strength is conventionally the 28-day value; US testing uses cylinders, much of Europe uses cubes
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Concrete specified in one market and supplied in another has to cross this boundary, and it is the one conversion here where getting the units right is not enough. American practice tests cylinders; much of Europe tests cubes; and the same concrete yields a higher number from a cube, typically by about a fifth. European grades such as C25/30 quote both figures precisely because they are not interchangeable, and comparing a cube strength against a US cylinder specification overstates the concrete by a margin that matters structurally. Convert the units, then confirm the specimen type before treating two strength figures as equivalent.