September 18, 2026

Concrete Cube Strength Calculator

By Admin

Concrete & Materials

Concrete Cube Strength Calculator

Calculate concrete compressive strength from maximum failure load and loaded specimen area, with SI and US customary unit support.

v1.0.1

Inputs

Test / reference basis Choose the reference basis used by your project. This selection does not alter the arithmetic strength calculation. Failure load Maximum load recorded by the compression testing machine at failure. Failure load unit Select the unit of the entered failure load. Loaded area Loaded cross-sectional area normal to the applied compression load. A 150 mm x 150 mm cube has an area of 22500 mm2. Loaded area unit Select the unit of the entered loaded area.

Results

Compressive strength — MPa Compressive strength in MPa (N/mm2).

Compressive strength — psi Equivalent compressive strength in psi.

Formula, assumptions & references

Formula notes

Compressive strength = maximum failure load / loaded cross-sectional area.
For load in kN and area in mm2: strength (MPa) = load (kN) x 1000 / area (mm2).

1 MPa = 1 N/mm2.
Worked example: 675 kN on 22500 mm2 gives 30.000 MPa, approximately 4351.1 psi.
QA 1: 675 kN and 22500 mm2 -> 30.000 MPa.
QA 2: 450 kN and 22500 mm2 -> 20.000 MPa.

QA 3: 900 kN and 22500 mm2 -> 40.000 MPa.
QA 4: 1000 kN and 40000 mm2 -> 25.000 MPa.
QA 5: 150 kip and 36 in2 -> approximately 28.728 MPa.

QA 6: 200 kip and 25 in2 -> approximately 55.158 MPa.

Assumptions

Failure load is the maximum valid load recorded during the compression test.
Loaded area is positive and represents the actual loaded cross-sectional area.

The calculator performs arithmetic strength calculation only.
No automatic cube-to-cylinder conversion is applied.
Use the governing laboratory standard and project specification for specimen preparation, loading rate, validity, and acceptance.

References

EN 12390-3, Testing hardened concrete - Compressive strength of test specimens.
ASTM C39/C39M, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens.

ACI 318, Building Code Requirements for Structural Concrete.
Applicable project and local concrete testing specifications.

This calculator provides failure load divided by loaded area. It does not determine acceptance of concrete or automatically convert cube strength to cylinder strength. Verify units, specimen dimensions, test procedure, and governing requirements before professional use.