The $\text{'}{\mathrm{R}}_{\mathrm{f}}\text{'}$(retention or retardation factor) value for any component in paper chromatography cannot be greater than

${\mathrm{R}}_{\mathrm{f}} \mathrm{value}=\frac{\mathrm{Distance} \mathrm{travelled} \mathrm{by} \mathrm{substance} \mathrm{from} \mathrm{base} \mathrm{line}\left(\mathrm{x}\right) }{\mathrm{Distance} \mathrm{travelled} \mathrm{by} \mathrm{eluent}\left(\mathrm{solvent}\right) \mathrm{from} \mathrm{base} \mathrm{line}\left(\mathrm{y}\right)}$ 

The distance travelled by solvent is always greater than the distance travelled by the component.

Hence,$\text{'}{\mathrm{R}}_{\mathrm{f}}\text{'}$ value lies between 0 to 1.

$\text{'}{\mathrm{R}}_{\mathrm{f}}\text{'}$ value zero means where component remains fixed at its origin.

$\text{'}{\mathrm{R}}_{\mathrm{f}}\text{'}$ value one means,that the component migrates as fast as with the solvent,which means that the substrate does not

bind with the stationary phase and travels with the solvent front.

$\text{'}{\mathrm{R}}_{\mathrm{f}}\text{'}$ value depends on temperature and nature of solvent used in the experiment.