As the name implies, doubling time is a term used to describe the time needed for a quantity to double in value. For an amount to double at some point, the quantity must increase by a certain amount each period of time. This increase is called a growth rate. If this increase stays the same over all periods, we can say that the growth rate is constant. There are two reasons why a constant growth rate is important:
- the constant growth rate leads to a constant doubling period. If the growth rate does not change from period to period, the doubling period will not change. It means that no matter the quantity, the time it will take the value to double will be the same. It will take the same amount of time for 1 to grow into 2 as it takes 2 to reach 4, or for 400 to reach 800, as long as the growth rate is constant.
- more importantly, the constant growth rate allows us to calculate the doubling time directly from the growth rate, enabling our doubling time formula calculator to do its magic.
As an interesting side note, doubling time is an application of compound interest, where the percentage increase is also calculated on all other previous increases. In this situation, it's searching for the time it takes to increase by exactly 100%. We write more about this topic in the compound interest calculator.
Doubling time is useful in a number of fields, including: finance (growth of money, compound interest, inflation), medicine (determining the growth of cancer), demography (population), and even mining (natural resources extraction). If you know the constant growth rate, you can use it to find out how long it will take to double the size of a population.
As you've probably noticed by now, the concept of doubling time is straightforward. So why do we need a doubling time calculator? The idea is simple, and the doubling rate equation is very short indeed. However, answering the question How to calculate doubling time by hand? is not that easy. Find out why below!
