# Tokyo & N.Y Doubling Time

Quantifying the rate of growth by calculating “Days for total deaths to double”

Calculating the number of days it takes for death to double, is another way to illustrate the rate of growth in more detail-based.

Let’s say, you would like to quantify the rate of growth in Tokyo and New York City around April 1st. You take the total deaths until April 1st and until March 25th (7 days before April 1st), then you can calculate that “The rate of growth around April 1st was that total death would double in Y days”. Please refer to the Appendix for the calculation formula.

Around April 1st, the rate of growth in Tokyo and New York City was “Doubling in 4 days” and “Doubling in 3 days” respectively. We can apply the same formula to each date in the past and create the chart as follows.

Y-axis shows “Y days” for total deaths to double as per the above explanation. The higher the number, the lower the rate of growth.

Disclaimer: The growth trend shown in the charts does not necessarily predict that same trend continues in the future.

Appendix – how to calculate the number of days for total deaths to double

The number of days for which total confirmed cases became double is calculated as follows.

For example, total confirmed cases in Tokyo was 1,914 on Day 32 and 897 on Day 25 (change in 7 days). In this case, we can calculate that

It means, based on data last 7 days, the total confirmed cases has become double in 6.4 days.