The completed family size may be estimated by:

The total feility rate gives the approximate estimation of completed family size. It represents the average number of children a woman would have if she were to pass through her reproductive years bearing children at the same rates as the women now in each age group. TOTAL FEILITY RATE = (SUM OF THE AGE SPECIFIC FEILITY RATES)*(AGE INTERVAL OF THE WOMEN) 1000 or TOTAL FEILITY RATE =*(AGE INTERVAL) 1000 Where For example: TOTAL FEILITY RATE IN 5 YEAR AGE GROUPS = 5 [?](AGE SPECIFIC FEILITY RATE) 1000 Ref: Park Textbook of Preventive and Social Medicine, 19th Edition, Pages 52, 53, 386, 387