What Is the Rough Opening For a 24″, 28″, 30″, 32″, 34″ And 36 Inch Door?

Ever wondered how carpenters and builders seem to install doors so seamlessly? The key lies in the accurate measurement of the “rough opening,” a term we’ll break down for you today. In this guide, we’ll discuss the standard rough openings for doors of sizes ranging from 24 inches to 36 inches.

What is a Rough Opening?

A rough opening is essentially the framed hole in a wall where a door will be installed. It’s crucial for ensuring that the door fits perfectly. Too small, and you’ll struggle to install the door; too large, and you’ll compromise on insulation and security.

Factors That Influence Rough Opening Size

Door Type

The type of door you’re installing plays a crucial role in determining the rough opening size.

  • Single Door: For a standard single door, the rough opening is generally 2 to 3 inches wider than the door width and 2.5 inches taller than the door height.
  • Double Doors: If you’re installing French doors or any double door set, you’ll need to consider the total width of both doors and potentially a central partition.
  • Sliding Doors: These require a rough opening width that is twice the door width to accommodate both the fixed and sliding panels.
  • Bi-fold Doors: These need a rough opening width that is the same as the combined width of the door panels and a bit extra for the tracking mechanisms.

Wall Thickness

The thickness of the wall where the door is being installed can also influence the size of the rough opening.

  • Standard Walls: For most residential interior walls, the thickness is around 4.5 inches, which includes the drywall. This usually doesn’t necessitate adjustments to the rough opening size.
  • Exterior Walls: These can be much thicker due to added insulation and exterior sheathing, requiring a potentially larger rough opening.

Additional Components

Various add-ons and components can also affect the rough opening size.

  • Door Frame: The door frame itself can add an extra 1.5 to 2 inches to each side of the door, affecting the rough opening width.
  • Weather Stripping: If you’re installing a door that needs weather stripping, this will also need to be considered in your measurements.
  • Thresholds and Sills: For exterior doors, you may also have a threshold or sill that could require extra height in your rough opening.

Calculating Rough Openings

General Formula

The general formula to calculate the rough opening size is fairly straightforward:

  • Width: Door Width + 2 to 3 inches
  • Height: Door Height + 2.5 inches
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For example, if you have a standard 32-inch by 80-inch door, the rough opening would usually be:

  • Width: 32 inches + 2 to 3 inches = 34 to 35 inches
  • Height: 80 inches + 2.5 inches = 82.5 inches

This formula accounts for the door frame, which usually adds 1.5 to 2 inches on each side, and also allows for minor adjustments during installation.

Special Cases

Certain types of doors and specific installation scenarios require deviations from the general formula:

  • Double Doors or French Doors: You’ll need to account for both doors’ widths and possibly a central mullion. So, you’ll take the combined width of both doors and add 2 to 3 inches, then add the width of the mullion if applicable.
  • Sliding Doors: These usually require a rough opening width that is twice the width of the door panel, as both the fixed and sliding panels need to fit into the space.
  • Bi-fold Doors: These doors fold upon themselves, and the rough opening needs to accommodate the combined width of all panels plus additional space for the tracking mechanisms.
  • Thick Walls: In some cases, extra-thick walls or walls with special insulation or soundproofing might require a wider rough opening to accommodate the added thickness.
  • Additional Components: If you’re planning on adding features like weather stripping, a door sill, or a specialized frame, these need to be included in your calculations.

Standard Rough Opening for a 24-Inch Door

For a 24-inch door, a rough opening of 26 to 27 inches in width and 82.5 inches in height is standard. These are commonly used for bathroom doors and closet doors.

Standard Rough Opening for a 28-Inch Door

A 28-inch door would usually need a rough opening that’s 30 to 31 inches wide and 82.5 inches tall. Such doors are often used for bedrooms.

Standard Rough Opening for a 30-Inch Door

The rough opening for a 30-inch door generally spans 32 to 33 inches in width and 82.5 inches in height. These doors are standard for bedrooms and living rooms.

Standard Rough Opening for a 32-Inch Door

For a 32-inch door, you’re looking at a rough opening of 34 to 35 inches in width and around 82.5 inches in height. These are often exterior doors.

Standard Rough Opening for a 34-Inch Door

A 34-inch door will usually require a rough opening of 36 to 37 inches wide and 82.5 inches high. These are less common but can be found in spacious homes.

Standard Rough Opening for a 36-Inch Door

For a 36-inch door, the rough opening would ideally be 38 to 39 inches in width and 82.5 inches in height. These are common for main entrances.

Special Cases: Bi-fold and French Doors


  • Bi-fold Doors:
    • Width: For Bi-fold doors, you’ll need a rough opening width that equals the combined width of all door panels plus about 2 inches for the tracking mechanisms.
    • Height: The rough opening height should be the door height plus around 2.5 inches for proper clearance.
  • French Doors:
    • Width: For French doors, you’ll calculate the rough opening width by adding together the widths of both door slabs, then adding an additional 2 to 3 inches. If there’s a central mullion, include its width.
    • Height: The rough opening height is generally the door height plus 2.5 inches, similar to single doors.
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Special Considerations

  • Bi-fold Doors:
    • Track and Hardware: Bi-fold doors usually come with tracking systems. Make sure to read the installation guidelines to factor in the required space.
    • Aligning Panels: As these doors fold onto themselves, they must be precisely aligned to operate smoothly.
  • French Doors:
    • Mullion or No Mullion: Some French doors come with a mullion (a vertical or horizontal bar), while others don’t. This will impact your rough opening calculations.
    • Sealing the Gap: Because there are two door slabs meeting in the middle, proper sealing is crucial to prevent air leaks or drafts.
    • Leveling: As with any double door system, leveling is critical. Both doors must align perfectly when closed.
  • Both Types:
    • Subfloor Level: Make sure your subfloor is level; otherwise, you might face challenges in fitting and operating either door type.
    • Additional Hardware: Sometimes, special hardware like door sweeps or transitional strips may be needed, so account for these in your rough opening calculations.

Common Mistakes to Avoid

Measuring Errors

Measuring errors are among the most common—and most costly—mistakes in door installation. Here’s how to avoid them:

  • Incorrect Rough Opening: People often miscalculate the rough opening dimensions, forgetting to add the necessary extra inches for the door frame and possible adjustments.
  • Ignoring the ‘Square’ Factor: A door might fit, but if the opening isn’t square, it won’t function correctly. Always double-check that your rough opening is square.
  • Not Measuring Door Slab: Always measure the door slab itself, not just the specifications given on the packaging or by the retailer. Sometimes there can be minor but critical differences.

Forgetting Wall Thickness

The thickness of the wall is another crucial factor that people often overlook, and here’s why:

  • Interior vs. Exterior: Interior walls are typically less thick than exterior walls, which may contain insulation and other layers. Make sure your door and frame are suitable for the wall’s thickness.
  • Extra Layers: Walls might have additional layers for soundproofing, thermal insulation, or aesthetics, like wainscoting. These layers can affect the depth of the door frame and should be included in your measurements.
  • Non-standard Wall Thickness: In some older homes or specialized constructions, walls might not have standard thickness. In such cases, you may need a custom door or frame.

Professional Tips for Perfect Installation

Tools Needed

Before you dive into the installation, make sure you have the following tools on hand:

  • Tape Measure: Accuracy is critical; make sure you have a reliable tape measure.
  • Level: To ensure that both the door and the frame are perfectly aligned.
  • Hammer: For nailing in the door frame.
  • Screwdriver Set or Power Drill: For securing screws tightly.
  • Chisel: To carve out areas where the hinges will go.
  • Circular Saw or Handsaw: For any needed adjustments to the door or frame.
  • Shims: To align the door properly within the frame.
  • Pencil: For marking measurements and hinge locations.
  • Utility Knife: For trimming and fine-tuning adjustments.
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Safety and accuracy are paramount during installation. Here are some precautions to keep in mind:

  • Double-Check Measurements: One mistake in measuring can throw off the entire installation. Always double-check your measurements.
  • Safety Gear: Don’t skimp on safety. Use goggles to protect your eyes from debris and wear gloves to protect your hands.
  • Check for Obstructions: Make sure the area where you’re installing the door is free from obstructions like electrical wiring or plumbing.
  • Ensure Level and Plumb: Use a level to make sure the door frame and door are perfectly horizontal and vertical. This is where those shims can come in handy.
  • Pre-drill Holes: Before screwing into the door or frame, pre-drilling holes can prevent the wood from splitting.
  • Test Before Finalizing: Before you put in the final screws or nails, test the door several times to make sure it opens and closes smoothly.
  • Seal All Gaps: Once the door is installed, ensure all gaps are sealed. This is especially important for exterior doors where you want to prevent drafts.


Understanding the dimensions of a rough opening is crucial for a successful door installation project. It varies based on the door size, wall thickness, and additional components.


Here are answers to some frequently asked questions about Rough Opening for a 32 Inch Door

1. What is the rough opening for a 32 by 80 inch door?

For a 32 by 80-inch door, the rough opening will generally be 34 to 35 inches in width and around 82.5 inches in height. This allows enough space for the door frame and provides some room for adjustments during installation.

2. How wide is a 32-inch door frame?

The frame for a 32-inch door typically adds an additional 1.5 to 2 inches on each side, making the total width of the door frame approximately 35 to 36 inches.

3. What size door is 32 inches?

When we refer to a “32-inch door,” we are talking about the door slab’s actual width, not including the door frame. The height is generally 80 inches unless specified otherwise.

4. What is the rough opening for a 36-inch door?

For a 36-inch door, the rough opening would ideally be 38 to 39 inches in width and about 82.5 inches in height. This size is standard for main entrances and allows room for the door frame and any other additional components.

5. How do I calculate door opening size?

To calculate the door opening size or the rough opening, add 2 to 3 inches to the door’s width and about 2.5 inches to its height. This will give you the dimensions for the rough opening, allowing for the door frame and any necessary adjustments.

6. What is the actual size of a 36-inch door?

The actual size of a 36-inch door refers to the width of the door slab itself, which is 36 inches. The height is usually 80 inches unless otherwise specified. This does not include the door frame, which adds additional width and height to the total dimensions.


A well-measured rough opening is essential for a smooth door installation. Always remember to consider all the influencing factors and to consult professionals if in doubt. Happy building!