Articles / data-notes

A 2.6 percent growth rate doubles a country in 27 years

نمو 2.6٪ يضاعف عدد السكان خلال 27 عاماً

2026-07-26

Here is the fastest trick in demography: divide 70 by the annual growth rate and you get the doubling time. Sudan grows at roughly 2.6 percent a year. Seventy divided by 2.6 is about 27 years.

Run it backwards and it checks out. Sudan held about 25 million people in the late 1990s and sits near 50 million now.

Germany, growing at essentially zero, will never double. Niger at 3.7 percent doubles in 19 years. Once you carry the rule of 70 around, growth rates stop being abstract and start being appointments on a calendar.