IQ tests can be a useful tool to assess your intellect and problem-solving skills. If you’re curious as to your own, there are ways you can find out. Make sure you’ll be comfortable whatever the result before you continue.
Find out if you’ve already been evaluated. It’s very possible that at some point in your life, you were tested. The numbers aren’t necessarily given to you if it was part of peripheral research into your psyche. There are a number of times it may have been given to you:
If you enlisted in the army, you’re often given an IQ test to see what you can handle and are capable of. If this could be you, contact your higher-ups to gain the results.
If you had experience with depression or other psychological issues, your psychiatrist may have given you the test. This is especially common if medications are part of your regimen.
If you were noted as “gifted” in school, you may have been given an IQ test. If it was when you were a child and you are an adult, you’ll have to take it again; the test for children is different.
Tap into your resources. If you haven’t taken it before, seek out all the available resources. It can be as free or as expensive as you’d like it to be. Know however, that free testing online is not accurate. A psychologist does testing that can’t possible be done online.
A local counseling center may be able to test you. Grab your phone book or search the online yellow pages for a center in your area.
A psychologist can offer you the test. This is the better alternative, both for accuracy and money-wise. If you’re testing because of a medical reason, like maybe you had a really bad concussion your insurance will cover the fees.
There are a plethora of online tests available. However, this is mainly for fun. This is not a legitimate way to fully test for IQ.
Take the test. There are actually a number of variations; you’ll want to consult an expert or do some thorough research to find out which one appeals most to you. Each test could give slightly different results as there is a standard deviation.
For adults, common options are Raven’s Progressive Matrices, the Wechsler Adult Intelligence Scale, the Stanford-Binet, and the Woodcock-Johnson Tests of Cognitive Abilities. Adult evaluation can be obtained starting at age 17. Your IQ at that age will not change much over the years. It measures potential rather than actual education. 
All tests will measure your spatial, mathematical, vocabulary, analytical skills, problem solving skills, and short term memory. This is how they get their feel for a “general” intellect. 
These tests are regarded as having high statistical reliability. That is to say, your true IQ is 95% likely to lie 3 points above or below the score you are given due to accepted deviation. Clinical psychologists generally regard them as having sufficient statistical validity for many clinical purposes. 
Method One of Two:
Know what your number means. The average person’s IQ is 100. On most tests, a score between 85 and 115, with the median deviation, indicates average intelligence. Even though humans have shown a pattern of rising 3 IQ points per decade, the scale is set so that the average is 100.  However, this is not a percentile and certain factors should be known.
Standard deviation is normally 15 points. 95% of the population lies with two SDs of the average, meaning that the vast, vast majority of people have an IQ between 70 and 130 always assuming SD=15 (think of your standard bell curve). 98% of people lie below 131. 
IQ scales are not just a number — they are ordinarily scaled. Therefore, an IQ of 50 is not half as much as an IQ of 100. These numbers are representative of cognitive ability — cognitive ability is not linear. 
Parents’ IQ scores are often within 10 points of their children’s. And there are other factors, too, like social status and environment. 
Take another test if you took your test on-line. If you are tested professionally twice, you’re number will be close, and your true IQ is somewhere between the two numbers. If you were particularly tired or frustrated, you may want to take it again.
Your IQ will vary from time to time, test to test, but only +- 1 SD. All the tests place you on a very similar level, much like scale you use to weigh yourself. Though weight scales may vary from scale to scale, you’ll get a pretty good idea no matter which one you use (especially if it’s been endorsed by a group of scientists).