Total Fertility Rate: A statistical scenario indicating how many live babies a woman would give birth to over the span of her reproductive years, a mathematical possibility based on the current age-specific fertility rates remaining constant throughout the course of a woman’s fertile years.
The calculation of the total fertility rate is a bit more complex than the formulas for the crude birth rate and the basic fertility rate. As such, the method for finding the TFR (total fertility rate) will be shown elsewhere.
But at this juncture it is important to note that when the TFR is higher than 2.0 (the possible number of children born to the average woman), the replacement rate either has been achieved, or perhaps has been achieved (depending on other factors like death rates, etc. in a territory).
In the United States, the replacement rate has been determined to be around 2.1, with the .1 being added for a variety of reasons like sex ratios and death rates. In some parts of the world, due to higher death rates, etc., the replacement rate is significantly higher than 2.1.
The TFR is a complicated statistical concept indicating a mathematical possibility, not an actual event. Think of the replacement rate as the sufficient level of births that could, in essence, replace the prior parenting generation that produced the children.