You need what is called a CMA or Comparable Market Analysis on your Home. You can do this yourself to a point but you should use the help of a Realtor.
"Free Home Value Analysis" or "Free CMAs" are only free if you list the property with a Realtor. They will take your address and compare it to properties that have sold in the last ~90 days within a 1 mile radius of your house.
If you check sites like here on Trulia or Zillow (I prefer Trulia) and do a search for your address, filter the searches so that they only show sold properties around your home, then filter it further to show square footage of the property, you can narrow it down to a few homes. Now this has to be narrowed down further to homes that match your property on the number of bedrooms and baths, year it was built and condition. Find properties that have been recently sold near your home that are as close as possible to your own home and take the average of the best 3 matches and you should have an idea of what your home value is.
Home Value is only good if someone is willing to pay that amount. So just because you think a property is worth so much based on what you purchased it for, it doesn't mean that is what people will buy it for today...it could be more...it could be less.
Realtors will visit your home and do a free listing on the condition that you will list with them. Once you sign on that line, you will get your free home value estimate. Once you sign on that line, know what you are signing, read everything and get copies. Do not get rushed into making a decision that you will regret in the future.
Try to steer clear from signing an exclusive contract for over 6 months and make sure you find an Agent that you like AND has great listings, meaning that they actually take the time to describe the properties they sell to the T, talking about the area, the features, and income that the property is bringing in along with the current expenses that go out, a video would be great. Make sure the agent has quality listings not just "a lot" of listings. The more listings an agent has the more their time is spread between managing all those listings.
If you are looking to sell, I actually work with Realtors and Attorneys that deal with traditional as well as creative ways of selling your house. There are about 13 ways to sell, how many can your Realtor list...why don't you ask him/her? There's an idea.
All the best!