Conversion between Cube and Cylinder Strengths

Generally a cylinder test strength is between 5% and 25% less than a cube test strength for a given concrete mix, the percentage difference decreasing with an increase in the concrete strength.

Firstmix uses the following matching values of cylinder and cube strengths to convert between cylinder and cube strengths, employing linear interpolation for intermediate values and linear extrapolation for values outside the range.

Cylinder Strength Cube Strength
MPa Psi MPa Psi
12 1740 15 2175
16 2320 20 2900
20 2900 25 3625
25 3625 30 4350
30 4350 37 5365
35 5075 45 6525
50 7250 60 8700

These values are taken from Table 8 of References 17.