How do I figure out correct angles?

I am trying to put moulding on my walls and all my cuts do not fit. I do not want to waste any more trim than I have to. I thought if I knew how to get angles i may be able to cut trim properly with a miter saw. Thank You.How do I figure out correct angles?
Here are several answers - you didn't specify baseboard or ceiling trim. Each is cut differently. The easiest way to cut ceiling trim is to first rip cut (lengthwise) a 12 or 18 inch piece of 2x4. Place that in your miter box with the slope facing you and rising toward you. You'll need to clamp this for safety. Now place your trim here and make the cut. This way you won't need the fancy math to figure compound angles.





Two tips for base trim...if it's only slightly open, you can choose to use the round shaft of a screw driver to roll over the joint at a slight angle. This will deform the wood slightly and close the gap. Pre-apply glue, if you wish and tape together until the glue dries. Alternatively, if the joint is close but not 'good enough' use one or more playing cards as spacers. If the joint is open, place the cards away from the cut. If the joint is tight, place cards near the cut.How do I figure out correct angles?
Most ';normal'; walls have a 90 degree angle, so you would want to cut both pieces of molding at opposite 45 degree angles to fit together. If your walls are slightly off, then you would need to adjust those cuts appropriately.





One way to see if your walls are perfectly 90 degrees is to get an adjustable protractor (available at Home Depot, Lowe's, etc). When placed in a corner and opened fully, it will let you know the degree of angle between the two walls. If it's not exactly 90 degrees, then you know to take the actual angle and divide by 2 to see what angle your molding needs to be cut at.





Also, a helpful tip... with the molding lying with it's flat side down, the molding on the left wall needs to be cut from the left angled down to the right. The molding on the right wall needs to be cut from the right angled down to the left.





Hope this helps.