How to Miter Corners

A woodworking joint -- molding pieces in the corner of a room, for example -- in which two boards are joined together at an angle is called a mitered joint.

Miters for Outside Corners

A board can be mitered at any angle, the most common being 45 degrees. Two 45-degree mitered boards joined together make a 90-degree corner angle. There are two types of mitered corners. Inside corners, where two walls meet, point inward, with the profile of the molding opposing itself. Outside corners point outward, with the profile facing away from the corner. Always wear eye and breathing protection when working with miter saws.

Step 1

Swing the blade of the miter saw to the left and lock it down at 45 degrees. Be sure the saw is stable and secure before making any cuts.

Step 2

Place the molding on the bed of the miter saw table, on the right side of the blade, with the top side of the molding facing your body. The back, or wall side, of the molding should be against the fence.

Step 3

Don safety glasses and a dust mask. Hold the molding against the fence with one hand, making sure it is well clear of the saw blade. Grasp the handle of the saw with the other hand. Turn on the saw and bring the blade down to trim 1 inch from the end of the molding. Allow the blade to return to the upright position, slow down, and stop.

Step 4

Swing the blade to the right side and lock it down at 45 degrees. Place an identical piece of molding on the miter saw on the left side of the blade, with the top of the molding facing your body and the back of the molding facing the fence. Bring the blade down to trim 1 inch from the end of the molding. Fit the mitered ends together to create an outside corner.

Step 5

Measure the length of each piece from the longest point of the angle or miter. Mark the measurement on both pieces of molding. Swing the blade to the 90 degree position to cut the molding off square, or miter the ends as needed for additional corners.

Miters for Inside Corners

Step 1

Swing the blade to the right side and lock it down at 45 degrees.

Step 2

Place the molding on the bed of the miter saw table, on the right side of the blade, with the top of the molding facing your body and the back of the molding against the fence.

Step 3

Don safety glasses and a dust mask. Turn on the saw and trim 1 inch off the end of the molding. Allow the blade to return to the upright position, slow down, and stop.

Step 4

Swing the blade to the left side and lock it down at 45 degrees. Place an identical piece of molding on the miter saw on the left side of the blade, with the top of the molding facing your body and the back of the molding facing the fence. Trim 1 inch off the end of the molding. Fit the two mitered corners together to create an inside mitered corner.

Step 5

Measure the length of each piece from the longest point of the mitered edge. Adjust the miter saw to 90 degrees to cut the molding pieces off square, or miter the ends as needed.

Things You Will Need

  • Miter saw
  • Safety glasses
  • Dust mask
  • Molding

About the Author

Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since 1972. Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine. Shaddy began publishing in various magazines in 1992, and published a novel, “Dark Canyon,” in 2008.