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.

These values are taken from Table 8 of References 17.