How to Level Base Cabinets Using Shims

Set a level on the top of the base cabinets to determine where the height differs. Draw a straight line above the cabinets using a ruler; draw the line from the highest cabinet to the end of the cabinets on the wall. Any cabinets that don't meet this reference line will need to be raised.

Determine how high the base cabinet will need to be raised. Measure from the top of the cabinet to the reference line quarter inch. Purchase shims that match this measurement -- quarter inch shims.

Lift the rear-corner of the base cabinet. Then wedge the appropriate shim underneath the rear-corner.

Look at your reference line to determine if the back of the cabinet is now the appropriate height. If not, insert a taller or shorter shim.

Place the level width-ways across the side of the cabinet to determine if the back of the base cabinet is level with the front. If not, the front of the cabinet will need to be shimmed also.

Pick the front-corner of the cabinet up just enough to wedge the appropriate size shim underneath.

Place the level width-ways again and make sure the front and rear of the cabinet are level. If not, readjust the shim as needed.

Check the other side of the cabinet to determine whether or not it will need to be shimmed. Place the level width-ways to make sure the back and front are level, and check to see if the back of the cabinet meets the reference line. If shims are needed in either the rear or front corner, repeat the steps to insert them.