The calculation are based on the percentages of parent, and daughter elements.
These calculations are based on geological assumptions of uniform process, the lack of erosion of either the parent or daughter elements.
Relative and absolute dating are dependent on the fossils and used to support the conclusions of the Darwinian order of descent with modification.
Radiometric dating (often called radioactive dating) is a technique used to date materials such as rocks or carbon, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.
The results are often determined by the estimates of the presumed age of the strata based on relative ages.
The age determined by relative dating is based on the rules of super imposition and the presumed age of strata based on fossils.
This means that absolute dating is basically the same as relative dating as it is based on the law of superimposition the most recent rocks are higher in the geological column.