Determine how much higher you want your coffee table to be. Table height is normally 30 inches. If you have stools or tall chairs, such as dining chairs, you will want to raise the coffee table to 37 inches.
Photograph of your coffee table legs. This will help determine the style of the pre-turned furniture legs that you buy from the local home center. Buy one leg for each leg of the coffee table. Match the stain or paint of the table while you are there.
Turn the coffee table upside down so the ends of the legs are in the air. Remove any non-wood material, such as casters, glides or foot protectors. You will need a wrench, hammer or wood chisel, depending on the type of hardware you must remove. Keep the hardware nearby because you may need to re-install it if the new legs didn't come with hardware.
Find the center of one leg of the coffee table. Mark the center with the pencil. Drill a 2-inch hole into the leg at the mark. Make the hole 1/4 inch deep. Place a few drops of wood glue into the hole. Tap one of the dowels into the hole firmly. Allow the assembly to dry. Repeat this step for each leg.
Set one of the pre-made legs on its side on a flat surface. Use the measuring tape to measure the length of leg you need to raise the coffee table and mark a line across one side at that height. Use a saw to cut the leg to size. Make the hole for the dowel in this leg as you did in Step 4, including putting glue in the hole.
Squirt a ring of wood glue on the bottom of the existing table leg. Fit the extension leg over the dowel. Tap the extension down over the dowel until it meets the bottom of the old leg. Make the edges even if you are using squared legs. Remove excess glue with the damp rag. Allow the leg to dry overnight. Stain or paint the extension to match the coffee table legs. Repeat this with each leg.