Door Rough Opening Size Guide: Standard Dimensions for All Door Sizes
Framing a door rough opening correctly is critical — too small and the door won’t fit, too large and you’ll have significant shimming and potential structural issues. The rough opening must accommodate the door slab, the frame (jambs), shims, and a gap for adjustment. This guide covers standard rough opening sizes for the most common interior and exterior door sizes.
Rough Opening vs Door Size
The door size refers to the door slab dimensions. The rough opening is the framed opening in the wall, which must be larger than the door and its frame. The standard rule is: rough opening width = door width + 2 inches (for jambs and shimming), and rough opening height = door height + 2.5 inches (for jamb, shims, and threshold clearance).
Standard Interior Door Rough Openings
- 2/0 door (24″): RO = 26″ wide × 82.5″ tall
- 2/4 door (28″): RO = 30″ wide × 82.5″ tall
- 2/6 door (30″): RO = 32″ wide × 82.5″ tall
- 2/8 door (32″): RO = 34″ wide × 82.5″ tall
- 3/0 door (36″): RO = 38″ wide × 82.5″ tall
Standard Exterior Door Rough Openings
Exterior doors use the same width formula but require slightly more height clearance for the threshold and weatherstripping. Standard exterior door rough openings are typically 2 inches wider and 2.5 inches taller than the door slab. A standard 3/0 × 6/8 exterior door requires a 38″ × 82.5″ rough opening.
Prehung vs Slab Doors
Prehung doors include the door slab, frame, and hinges as a unit. They’re easier to install but the rough opening must match. Slab doors are just the door panel and require an existing frame — used for replacement doors only. Pre-hung doors are the standard for new construction and renovation projects where you’re framing a new opening.
Header Sizing for Door Openings
The header above a door rough opening carries loads from above. In a load-bearing wall, header sizing depends on the span (door width) and loads. A 2×6 doubled header works for openings up to about 4 feet in most single-story applications. Wider doors require larger headers — consult span tables or your local building code for specifics.
Plan your door framing. Use the Door Rough Opening Calculator on diycalculator.net to get precise rough opening dimensions for any door size.