Door Frame Materials Calculator
Calculate jamb, casing, and shim materials from rough opening size.
Returns linear feet and a cut list for interior and exterior door frame installations.
Door framing involves three distinct phases: the structural rough opening in the wall framing, the finish jamb that lines the opening, and the decorative casing that trims both sides of the finished wall.
Rough opening size (structural framing):
Rough Opening Width = Door Width + 2 inches (for jamb + clearance)
Rough Opening Height = Door Height + 2.5 inches (for jamb, threshold, and clearance)
Standard door rough openings:
| Door Width | Door Height | Rough Width | Rough Height |
|---|---|---|---|
| 24" (2'0") | 80" (6'8") | 26" | 82.5" |
| 28" (2'4") | 80" (6'8") | 30" | 82.5" |
| 30" (2'6") | 80" (6'8") | 32" | 82.5" |
| 32" (2'8") | 80" (6'8") | 34" | 82.5" |
| 36" (3'0") | 80" (6'8") | 38" | 82.5" |
| 36" (3'0") | 96" (8'0") | 38" | 98.5" |
Finish jamb components:
Side Jamb Length = Rough Opening Height − Floor to Finish Floor Thickness
Head Jamb Length = Rough Opening Width + 2 × Jamb Thickness
Standard jamb thickness = 1-1/16 inch (27 mm) for 4-9/16" wall or 1-3/8" for thicker walls. Jamb width must match your wall thickness: 4-9/16" for 2×4 construction + drywall, 6-9/16" for 2×6 construction.
Casing / trim components: Casing is installed on both faces of the wall around the door.
Side Casing Length = Door Height + Reveal + Miter Allowance (add ~3")
Head Casing Length = Door Width + 2 × Reveal + Miter Allowance (add ~6")
Reveal = the visible setback from the jamb edge, typically 3/16"–1/4" (5–6 mm).
Shim pairs: Shims are used to plumb and level the jamb within the rough opening. Install shim pairs every 16 inches along each side jamb (typically 3 locations per side) and behind each hinge location.
Materials list for a standard 32"×80" interior door:
| Item | Quantity |
|---|---|
| Side jambs | 2 × ~82" lengths |
| Head jamb | 1 × ~35" length |
| Side casings (per side) | 2 × ~86" per face |
| Head casings (per side) | 2 × ~39" per face |
| Shim pairs | 8–10 pairs |
| Door stop (optional) | 3 pieces (2 sides + head) |
Pro tip — pre-hung vs. build-in-place: Pre-hung doors (door slab already mounted in the jamb assembly) cost more but eliminate most of this measuring and cutting work.