To see which electrical standard is used in your country, see one of these sources: Wikipedia – Mains Electricity by Country or the U.S. International Trade Administration.

The following list is a general guideline; you should check electrical standards in your area to ensure you order the correct product:
Europe: 50 Hz
North America: 60 Hz (includes USA, Canada, Mexico, Central America)
Africa: 50 Hz (check locally in Liberia)
Asia: 60 Hz in Philippines, South Korea, Taiwan, and southern regions of Japan (incl. Nagoya, Osaka, Shizuoka, Kyushu, Okinawa)
50 Hz in most countries not listed above (including China, India, Israel, Malaysia, Singapore, Thailand, Turkey, U.A.E., Vietnam);  also northern parts of Japan – Hokkaido, Tohoku, and Kanto regions (incl. Tokyo, Sendai, Sapporo)
Australia/New Zealand: 50 Hz
Caribbean: check link
Oceania/Pacific Islands: check link
South America: 50 Hz in Argentina, Chile, Paraguay, Uruguay
60 Hz in countries not listed above (including Brazil, Colombia, Ecuador, Peru, Venezuela)