A general contractor or an architect can come out and assess your situation. But if you want to try and figure it out yourself just look at the space and decide what would be the most economical way for the structure above to run. Typically lets say in a kitchen that is maybe 14 feet deep and 20 feet wide, the joists would have run the shorter span of 14 feet and the wall the joists are sitting on would be the bearing wall. You can also go in the basement if unfinished and see the row of columns and what direction they run. But to be 100% sure you need to poke a hole in the ceiling. Good luck!
The best way is to cut an access hole into the ceiling to see if either floor joists for a second floor are resting on it or if ceiling joists are resting on it. If you can determine this, then you will know if a beam is needed to carry whatever the wall is supporting. Good luck and be careful.
To determine if the wall that you want to remove is a load bearing of not: If the ceiling or floor joist are running perpendicular to the wall, that could mean that the wall is load bearing. To verify, go up to the attic to see where the wall is located in relation to the joist layout. Same idea if you have a wall in a unfinished basement and you can see the joist layout. If you are not comfortable, contact a contractor to look at the wall before the work is to begin.
Check the joists. For any building contractor this is Course 101A.
Go to your city hall and get a record of your house plans. Purchase it from them and then go to any lumber store. Ask any of their associates; usually they are very knowledgeable in structural questions.
Hiring a professional such as a contractor or structural engineer.
It depends on where the wall is located and if the home or building is one story or multiple stories. Always seek help from a professional because the wall may not be a load bearing wall but could be a shear wall which provides lateral resistance during earthquakes.
If it is a load bearing wall, it should be common sense to anyone with adequate experience in the construction building trade…is the wall supporting any other framing members? If above the wall you have attic space, you can take a look from the attic and see if the wall is supporting roof rafters, ceiling joists, kickers, purlins etc. If the wall is below a floor level, then you will have to cut into the ceiling to see if the wall is supporting any floor joists and you should also check if there is a wall directly above the wall in question.
Get a professional general contractor or an architect to come over and look at it. This determination should not be done by anyone that is not qualified.
You must look into the addict and determine if this is load bearing wall or not. You can also remove the drywall and determine it that way.
Never do anything before asking a professional, or you can get into trouble!!!
A quick and easy way to determine a load bearing wall is to go in the attic and look at which direction your joists run (if not easily accessible, you can go into crawl space or unfinished area in basement to see joists). If the ceiling or floor joist are running perpendicular to the wall, that could mean that the wall is load bearing (99% percent of the time). If you have any doubt, please contact a contractor to look at the wall before any work is to begin.