Muslims who fast in Ramadan do not always fast for the same period of time. Depending on where they are in the world, depending on the time of the year, fasting hours often fluctuate.
In Brazil, fasting will last only for 10 hours. In Australia and South Africa, it is 11 hours.
At the other end of the world in the Northern hemisphere, fasting hours last an arduous 21 hours in Greenland.
Parts of Scandinavia and Russia also have over 18 hours of fasting due to the extended daylight in the regions.
Bangladeshis have to fast for 15 hours. In the Middle East, it is 14 hours.