Visit American Mensa website. This international organization is recognized worldwide for its success in devising and administering IQ tests. There are home tests available, in addition to those taken at the Mensa Institute.
American Mensa, Ltd.
1229 Corporate Drive West
Arlington, TX 76006-6103
817-607-0060
us.mensa.org
Join the US Army. The US military requests all new recruits take a standardized IQ test --- the Armed Forces Qualifying Test --- to get an impression of a soldier's cognitive abilities.
Contact a psychologist in your area. For a fee, almost all psychologists will be able to assess your IQ level. Depending on your reasons for taking the IQ test, it may be covered by your health insurance.