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Total Fertility Rate Formula:
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The Total Fertility Rate (TFR) represents the average number of children a woman would have over her lifetime if she experienced the current age-specific fertility rates throughout her reproductive years. It's a key demographic indicator for population studies.
The calculator uses the TFR formula:
Where:
Explanation: The formula sums the age-specific fertility rates across all reproductive age groups (typically 15-49 years) and multiplies by the age interval width to estimate the total fertility over a woman's reproductive lifespan.
Details: TFR is crucial for understanding population growth patterns, planning social services, and formulating population policies. A TFR of 2.1 is generally considered the replacement level fertility rate in developed countries.
Tips: Enter age-specific fertility rates for each 5-year age group from 15-19 to 45-49 years. All values must be valid (non-negative numbers). The calculator will sum the rates and multiply by 5 to get the TFR.
Q1: What is the difference between TFR and crude birth rate?
A: TFR measures the average number of children per woman, while crude birth rate measures the number of births per 1000 population per year.
Q2: Why multiply by 5 in the formula?
A: The multiplication by 5 accounts for the 5-year width of each age interval, converting annual rates to total fertility over the reproductive lifespan.
Q3: What TFR value indicates population replacement?
A: Approximately 2.1 births per woman is considered replacement level fertility in most developed countries.
Q4: How often should TFR be calculated?
A: TFR is typically calculated annually using the most recent fertility data to track population trends.
Q5: What are the limitations of TFR?
A: TFR assumes that current fertility patterns will continue and doesn't account for changes in timing of childbearing or mortality rates.