What is the difference between fertility rate and fertility ratio?

The fertility rate and fertility ratio are related but distinct demographic measures. The fertility rate, or the total fertility rate (TFR), is the average number of children a woman would have during her reproductive years, assuming that age-specific fertility rates remain constant. It measures the level of fertility in a population. On the other hand, the fertility ratio, or the general fertility rate (GFR), is the actual number of live births per 1,000 women of childbearing age (typically between 15 and 49 years old) in a given year. It measures the current level of fertility in a population.