Where: \(V_{mix}\) is the volume of the entire gradient (typically the volume of the ultracentrifugation tube), \(\rho_{mix}\) is the desired final density of the gradient mixture, \(\rho_{CsCl}\) is the density of the CsCl solution, and \(\rho_{\left(GB+DNA\right)}\) is the density of the gradient buffer and DNA mixture. The rest of the volume should be filled with the mixture of GB and DNA. The density of GB is around 1.01 g ml-1, while that of DNA solution is very close to 1 g ml-1. Although the exact density of the GB + DNA solution can be calculated, depending on the volume of the DNA sample, the effect of the latter on the overall density is negligible, and it is safe to assume that the density remains unchanged. Hence equation \ref{eqn:mix1} can be re-written as follows: