A great fit starts with knowing where to put the tape. Follow this guide for a single door, double door, or an entrance with sidelites and a transom.
Stand outside and note whether you have a single or double door, sidelites on the left or right, and a transom above. Take a photo of the whole entrance from both sides. Measure each opening separately.
Have a tape measure, pencil, level, and a helper ready. Record inches to the nearest 1/16 inch, with width before height. Label each measurement as slab, frame, or rough opening.
Open the door and measure the moving panel itself: edge to edge for width, and top to bottom for height. Exclude the frame, sill, weatherstripping, and any sweep attached below the slab. On a double door, record each slab separately.
In the configurator, “Nominal width” is the size name: a 36-inch selection represents a 35¾-inch-wide slab. “Slab height” is the stock slab height. These fields are not the dimensions of the opening in your wall.
Measure from the outside edge of one frame jamb to the outside edge of the other. Include all sidelites and the posts between them. Measure height from the underside of the sill to the top of the frame, including the transom when present. Exclude casing and exterior brickmould.
Use “Overall frame width” for an entrance with sidelites, and “Overall frame height” for an entrance with a transom. If trim hides the frame edges, mark the measurement unconfirmed rather than measuring the trim as the frame.
If the structural opening is exposed, measure between the framing at the top, middle, and bottom. Measure from the sill support to the header at the left, centre, and right. Record all six readings and identify the smallest width and height. Compare both diagonals and check that the sill support is level.
The rough opening is larger than the finished door frame. Installation clearance depends on your opening and selected system; have your installer confirm it. Do not enter rough-opening measurements as slab sizes or apply a window-size deduction. If framing is concealed, leave this measurement unconfirmed.
Measure the required frame depth from the exterior frame face to the interior finished wall face, excluding decorative trim. Record this separately from the opening width. Note floor finishes, the sill condition, and clearance for the door to swing.
Describe handing while standing outside: hinges on the left or right, and whether the door opens inward or outward. For double doors, identify the active door. A photo with the door open helps us confirm these details.
Choose the slab size first, then review the complete frame dimensions for your selected layout, swing, and sill. For a cut-down door, enter “Finished door frame height”: bottom of sill to top of the door frame, excluding a transom and exterior trim. This is not the finished slab height.
For a shaped top or transom, also record the highest point and the height where the curve or slope begins. If anything is uncertain, keep “Help me measure” selected and save your design. Confirm the measurements before adding the door to your cart.