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How to use the formula to calculate the Total Fertility Rate (TFR) and the Age Specific Fertility Rate (ASFR)

Updated on June 19, 2012

The Total Fertility Rate(TFR) is a fertility rate or birth rate used in demography to help understand the fertility experience and demographic processes of a particular population. The Total Fertility Rate (TFR) can be defined as "…the average number of children that would be born per woman if all women lived to the end of their childbearing years and bore children according to a given fertility rate at each age" (CIA World Factbook) It is one of the most used measurements to compare populations in demography. However, before you can calculate the Total Fertility Rate, you must calculate the Age Specific Fertility Rates (ASFR) for the women of childbearing years in a population.

Age Specific Fertility Rate (ASFR)

Typically, Age Specific Fertility Rates are done in 5 year age groups for women between the ages 15 - 49 or 18 - 49, depending on the available data and population. The formula for the Age Specific Fertility Rate is:

Age Specific Fertility Rate (ASFR) = (Number of births to women in age group i / Number of women in age group i) x 1000

Total Fertility Rate (TFR)

After calculating all of the Age Specific Fertility Rates for the population, you can move on to calculating the Total Fertility Rate. The formula for the Total Fertility Rate is:

Total Fertility Rate (TFR) = (The sum of the Age Specific Fertility Rates x The number of years in each age group) / 1000

The final number you arrive at is the Total Fertility Rate (TFR) for the studied population. A Total Fertility Rate of 2.1 is considered replacement fertility which means that the population is stable (although this is not the case in high mortality populations), above or below means that the population is growing or shrinking. Furthermore, it is important to understand that women of the studied population have not experienced nor necessarily will experience the Total Fertility Rate of any given year.

Sources: CIA World Factbook, On the Quantum and Tempo of Fertility, Measure Evaluation


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      Arun gyawali 14 months ago

      very useful information for me..thank you

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      Bidyut 24 months ago

      Thank you, its easy to remember

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      Dina 2 years ago

      so simple and easy to understand

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      Abekebe 2 years ago

      Thanks! Very Supportive!

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      numan 2 years ago

      Really very helpfull.

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      isaiah hunuato hunis 2 years ago

      nice work. more grace to you

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      bhaskar 3 years ago

      Thank you very helpfully

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      mbah nadege adoh 3 years ago

      i really wish to be part

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      Clemmence 3 years ago

      Extremely helpful. Thax a lot

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      man 3 years ago

      Very helpful. Thank you

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      swornim adhikari 4 years ago

      that's very useful one

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      sudarsan raju k 4 years ago

      It is very useful

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      Heather Jacobs 5 years ago

      Hi Giselle. Thank you very much! I'm glad you found it helpful!

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      Giselle Maine 5 years ago

      A helpful definition of how this number is actually derived. Thanks for this useful hub.