Hi Fran. This KitchenAid® Microwave has a width of 21 3/4 inches, a height of 12 1/2 inches, and a depth of 20 1/2 inches. So, the Microwave will fit in the space you have. However, since the depth of the Microwave is larger, it will protrude farther than the side walls. As far as the clearance needed for installation, make sure the surrounding cabinetry has clearance to open and close freely. Allow a clearance of at least 1⁹⁄₁₆" (4.0 cm) below the cutout floor (3" [7.6 cm] for installation above a built-in oven), and a clearance of at least 2" (5.1 cm) above the cutout opening. We hope this information is beneficial to you!