Door Rough Opening Calculator

Calculate exact rough opening dimensions, header sizing, and framing member requirements for any door type — interior, exterior, sliding, bifold, or pocket.

Door Configuration

Door Type

Door Width

inches

Door Height

inches

Wall Framing

Number of Doors

doors

Wall Height (inches)

in (for cripple/king stud calc)

Rough Opening

—

width × height

—

RO Width (inches)

—

RO Height (inches)

—

RO Width (ft-in)

—

Header Size

Framing Members

Door Framing Diagram

Header Sizing by Span

Minimum header sizes for exterior bearing walls (1 story above, Douglas Fir-Larch No. 2). Interior non-bearing walls may use lighter headers per IRC. Consult your local code for specific requirements.

Multi-Door Rough Opening List

Add doors from the Calculator tab using the "+ Add to List" button. All rough openings and headers calculated automatically.

Framing Reference Guide

2×4 vs 2×6 Wall Framing

2×4 walls: 3.5" actual depth — standard for interior partitions and most exterior walls in mild climates
2×6 walls: 5.5" actual depth — used for exterior walls in cold climates to accommodate R-19–R-21 insulation
Header depth must match the wall thickness — use a plywood spacer with 2×6 walls to reach 5.5" depth
King and trimmer studs are the same length regardless of wall thickness

Shimming Practices

Standard RO adds 2" to width and 2.5" to height for shimming and plumb/level adjustment
Shims fill the gap between the door frame and rough framing — typically 1/4" to 1/2" per side
Always check and set door jamb plumb in both planes before securing shims
Shim at hinge and strike plate locations for maximum support

ADA Door Width Requirements

ADA minimum clear opening width: 32 inches (door leaf at 90°)
Preferred ADA clear width: 36 inches for easy wheelchair passage
A 32" door provides a 29.5"–30" clear opening (accounting for door thickness)
A 36" door provides the full 34"–34.5" clear opening recommended for accessibility

Special Door Types

Sliding Patio: RO width = opening width + 1" (single side shimming)
Bifold: RO width = panel width + 1" for the track and shimming
Pocket Door: RO width = 2× door width + 1" for the pocket frame and door thickness
French Doors: Each leaf treated as individual door; combined RO = sum of both leaves + 2"

Rough Opening Rules Quick Reference

How to Use This Calculator

Select door type — Choose Interior, Exterior, Sliding Patio, Bifold, or Pocket. Each type has a different RO formula because the frame and hardware requirements differ.

Choose door width and height — Use the preset standard sizes (24", 28", 30", 32", 36" wide; 80", 84", 96" tall) or enter a custom dimension.

Select wall framing type — 2×4 (standard) or 2×6 (common for insulated exterior walls). This affects header sizing recommendations.

Enter number of doors and wall height — The wall height is used to calculate king stud length and cripple stud count above the header.

Read the framing diagram — The SVG shows king studs, trimmer studs, header, and cripple stud positions for the calculated opening.

Build a multi-door schedule — Click "+ Add to List" to build a job schedule for multiple doors across your project.

Framing Terminology

Rough Opening (RO)The framed opening in the wall into which a door or window unit is installed. Larger than the door unit to allow shimming and adjustment.

King StudFull-height stud running from bottom plate to top plate on each side of an opening. Supports the ends of the header.

Trimmer Stud (Jack Stud)Shorter stud nailed to the inside of each king stud. Runs from the bottom plate to the underside of the header, bearing the header load.

HeaderDoubled horizontal lumber spanning the top of an opening. Transfers loads around the opening to the trimmer and king studs. Must be sized for the span.

Cripple StudShort studs above a door header (between header and top plate) that maintain stud spacing for panel nailing and transfer loads to the header.

Prehung DoorDoor unit that comes with the frame (jamb) pre-attached. The most common residential door installation method. RO must accommodate the full unit width and height.

Pocket DoorDoor that slides into a cavity in the wall. Requires a doubled rough opening width to accommodate the door in the pocket plus the active opening. Special metal stud frames are used.

Bifold DoorDoor that folds in half along a track at the top and bottom. Common for closets. RO is typically equal to the opening width plus 1 inch for track hardware.

Frequently Asked Questions

Why is the rough opening 2 inches wider than the door?

A prehung door unit includes a frame (jamb) that is approximately 1.5 inches on each side (made from 1× lumber at about 3/4" actual plus the door stop). The extra width (and height) provides room for shimming the frame plumb and level. Without this clearance, the door frame would be a tight fit in a potentially out-of-square opening and would be extremely difficult to install correctly.

How do I size headers for interior non-bearing walls?

Non-bearing interior walls do not carry loads from above, so headers can be much lighter. For openings up to 8 feet in non-bearing walls, the IRC allows a single flat 2×4 header with cripple studs above. Many builders use a doubled 2×4 or 2×6 for consistency and to provide a nailing surface for finish materials. Check with your local code authority before using a non-standard header.

What is the rough opening for a 32-inch exterior door?

For a standard 32" × 80" prehung exterior door, the rough opening is 34" wide × 82.5" tall. The 2" extra width accounts for the jambs (3/4" each side) plus shimming clearance. The 2.5" extra height accounts for the sill plate height and shimming at the bottom. For some exterior doors with a threshold that sits on top of the floor, verify the exact RO with the manufacturer's installation instructions.

How does a pocket door rough opening differ from a standard door?

A pocket door requires a rough opening that is approximately twice the door width, because the door slides entirely into the wall cavity when open. For example, a 32" pocket door needs a 65" (2 × 32 + 1) rough opening width. The pocket frame (usually a metal split-stud kit) fills the rough opening. The door itself uses a 32"-wide opening when installed; the rest is the pocket cavity.

Can I use LVL or steel for door headers instead of doubled lumber?

Yes. LVL (Laminated Veneer Lumber), PSL (Parallel Strand Lumber), and steel headers are all code-permitted alternatives and are often preferable for wide openings or when dimensional lumber headers would be too deep. LVL headers are typically 1.75" wide and need a plywood spacer to fill a 2×4 or 2×6 wall. Always verify header selection with your engineer or per manufacturer span tables.