Most real estate agents offer a free home valuation. This of course happens with an eye on the fact that you actually want to sell your property and you see this broker as a serious candidate to do that for you.
A good real estate agent does not determine the value of your home by wetting his finger, raising it and saying that he thinks this X euro is worth it. With a good valuation, the broker does a prior investigation at the Land Registry, comes along, views your property on structural condition, maintenance condition, layout, possibilities, details and measures the property to determine the total area. Then he will compare your home at his office and plus and minus with transactions that have taken place in your area. He determines the home value and ensures that he can also substantiate this. He will often offer you this home value determination together with a sales plan.
If you want to sell your property (perhaps) and want to know how much it is worth, first look for 2 or 3 good real estate agents and invite them.