The relationship of the volume of space-time (L3) to mass can be presented by  

Where: 
m=mass , g=constant (matter to space-time conversion factor), L=length

The above presents a simplistic classical relationship which explains how a certain amount of matter of mass m (kilogram) melts away into creating a volume of space of the order of  L3 (cubic meter).

The constant g must be calculated by observations or measured by experiment.