Recombination frequency is a number that describes the proportion of recombinant offspring produced in a genetic cross between two organisms.
Recombination frequency shows us if two genes are linked, and how tightly, by using data from the genetic crosses.
Formula to calculate recombination frequency.

Recombinant is a general name given when a piece of one DNA is combined with another DNA giving rise to a new DNA.
Example:
Suppose the number of recombinants in a family is 10 while the total number of off springs in that family are 20, calculate the recombination frequency.

Therefore, the recombination frequency is 50%.