Built-in Double Ovens. Measure the distance between the left side of the oven and the right side. It should be 27 or 30 inches. A 27-inch oven will require a cabinet width cutout between 24 7/8 inches and 25 1/4 inches.A 30-inch oven will needs 28 1/2 to 29 inches.Measure the distance from the top to the bottom of the oven.ou will need 1/8-inch clearance between cabinets or walls on either side at the oven level (below 36 inches.) You'll need 1 inch above 36 inches from the floor. Measure the oven depth from the wall with the largest door open. It is likely to be 46 inches. Allow some extra space in front of that for you to stand.