O you who believe, fasting is decreed for you, as it was decreed for those before you, that you may attain salvation. (2:183)
Ramadan is the month during which the Quran was revealed, providing guidance for the people, clear teachings, and the statute book. Those of you who witness this month shall fast therein.... (2:185)
20 July 2012 - 17 August 2012: Therefore, God willing the first day of Ramadan is July 20, and the last day of Ramadan is August 17 for most of USA, Canada and Mexico. Hawaii, parts of Alaska and north west Canada have the beginning for the month of Ramadan a day earlier (July 19th).
These Ramadan dates God willing are also for: South America, Europe, WesterN Asia (e.g., Syria, Turkey), Africa (e.g., Egypt, Libya, Morocco, Nigeria, South Africa)
20 July 2012 - 18 August 2012: The first day of Ramadan is July 20, and the last day of Ramadan is August 18, for most of Asia (including Bangladesh, India, Indonesia, Malaysia, Pakistan, Singapore), Middle-East (e.g., Iran, UAE), Eastern Africa (e.g., Kenya), Australia and New Zealand.
Please check your local sunset times to verify these dates. For example, the last day of fasting may be, God willing, August 17 for some countries in Middle East and Africa even though they start fasting on July 20, 2012. Hawaii and a few areas on the north-west US and Canada, begin on July 19th.