The following is a calculator that can be used to make estimates about the exponential growth phase of the COVID pandemic.
It is purely a mathematical estimator, and has no underlying insight into the disease growth patterns, but can be used as an informational tool for projecting and observing patterns.
Calculate Growth Rate
Enter two dates where the number of cases is known, and the respective number of cases, then the result will be shown.
Some examples:
- New York Mar 10, 2020: 173 cases => Mar 25: 30811 cases indicates a doubling rate of 2.01 days, however the numbers recorded on the 27th (44,635) indicate a doubling rate of closer to 3, meaning the growth is slowing.
- Ontario Mar 11, 2020: 42 cases => Mar 23: 425 cases indicates a doubling rate of 3.59 days.
- Ontario Mar 23, 2020: 425 cases => Mar 28: 994 cases indicates a doubling rate of 4.08 days, suggesting that the doubling rate is slowing.
The start date and the second cases will be automatically copied into the estimate below.
Estimate future cases
Enter the start date, the current number of cases, and number of days the cases double, and estimates will be calculated in a table.
Of course these estimates are inaccurate in the very-short term, and they become wildly inaccurate in the very-long term because the exponential growth rates quickly exceed the global human population, and the speed at which the disease propagates leaves an exponential growth phase.
Formulas
The doubling rate is calculated with:
days × logn(2) / logn(count2 / count1)
being a doubling time formula.
The estimate of future cases follows the formula:
cases × 2days / days-to-double
The estimates stop at 1 billion or 365 days.