Interior Door Planning Guide

Interior Door Size Guide

Choosing the right interior door begins with accurate measurements. This guide explains common door widths, heights, thicknesses, rough openings, double doors, closet doors, pocket doors, bifold doors, and bypass doors.

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Understanding Interior Door Sizes

Interior doors are available in many sizes, but most homes use a relatively small group of standard widths and heights. The correct size depends on the room, wall construction, door style, required clear opening, and hardware.

Door Width

Width is measured from one vertical edge of the door slab to the other. Common residential widths range from 24 to 36 inches.

Door Height

An 80-inch door is common in residential construction. Taller 84-inch and 96-inch doors are also used in newer homes and custom designs.

Door Thickness

Most residential interior doors are 1 3/8 inches thick. Heavier, taller, solid-core, or custom doors may be 1 3/4 inches thick.

Common Interior Door Sizes

Door sizes are normally listed as width by height. A door described as 30 inches by 80 inches is 30 inches wide and 80 inches high.

Nominal Door Size	Common Use	Planning Notes
18 x 80 inches	Small closets or utility access	Provides limited access and may not suit frequently used rooms.
20 x 80 inches	Linen closets or narrow storage areas	Useful when wall space is limited.
24 x 80 inches	Closets, pantries, and small bathrooms	Compact, but may feel narrow for everyday passage.
28 x 80 inches	Bathrooms, bedrooms, and utility rooms	A common choice where space is restricted.
30 x 80 inches	Bedrooms, bathrooms, and home offices	A widely used residential interior-door size.
32 x 80 inches	Bedrooms, hallways, and accessible routes	Offers easier movement than narrower doors.
34 x 80 inches	Wider room entrances	Useful when additional clearance is desired.
36 x 80 inches	Main rooms, laundry rooms, and wider passages	Provides generous access for furniture and equipment.
30–36 x 84 inches	Homes with taller ceilings	Requires a compatible frame, jamb, and hardware system.
30–36 x 96 inches	Custom homes and 8-foot openings	Taller doors may require stronger or higher-capacity hardware.

Important: Door-slab size is not the same as rough-opening size. The framed opening must provide room for the jamb, shims, fasteners, adjustment, and required clearances.

Door Size Terms You Should Know

Door Slab

The slab is the door itself, without a frame. Slab doors may be used for replacement projects or installed with separately selected jambs and hardware.

Prehung Door

A prehung door is supplied already mounted in a jamb. The complete unit is installed into the framed rough opening.

Unit Size

Unit size is the outside measurement of an assembled door and frame. It is larger than the door slab but smaller than the rough opening.

Rough Opening

The rough opening is the framed opening in the wall before the door frame, jamb, track, or pocket-door system is installed.

Finished Opening

The finished opening is measured after the jamb, trim, track, or other finished components are in place.

Clear Opening

Clear opening is the usable passage space remaining when the door is open. It may be smaller than the nominal door width.

How to Measure an Existing Interior Door

Measure the door and opening in several places. Older homes may have floors, walls, and frames that are not perfectly square.

Measure the Width

Measure the door slab from left to right. If measuring an opening, measure across the top, middle, and bottom. Record the smallest result.

Measure the Height

Measure from the top edge of the door to the bottom edge. For an opening, measure both sides and the center. Record the smallest result.

Measure the Thickness

Measure across the door edge. Common thicknesses are 1 3/8 inches and 1 3/4 inches, but older or custom doors may differ.

Measure the Jamb Depth

Measure from the front edge of the jamb to the back edge, excluding the casing. Match the jamb to the finished wall thickness.

Check the Floor

Account for carpet, tile, hardwood, underlayment, thresholds, and any planned flooring changes before determining the final door height.

Check for Square

Measure diagonally from corner to corner in both directions. Unequal measurements may indicate that the opening is out of square.

Replacement tip: Do not order a replacement door from a single measurement. Check the slab, jamb, rough opening, floor clearance, handing, swing direction, hinge locations, and hardware preparation.

Interior Door Rough-Opening Sizes

A rough opening must be larger than the door slab. For a conventional prehung swinging door, a common planning estimate is approximately 2 inches wider and 2 to 2 1/2 inches taller than the nominal slab.

Door Slab	Common Planning Estimate	Before Framing
24 x 80 inches	About 26 x 82 to 82 1/2 inches	Confirm the prehung unit manufacturer's instructions.
28 x 80 inches	About 30 x 82 to 82 1/2 inches	Allow for jambs, shims, and adjustment.
30 x 80 inches	About 32 x 82 to 82 1/2 inches	Check finished-floor height before installation.
32 x 80 inches	About 34 x 82 to 82 1/2 inches	Verify the required clear passage width.
36 x 80 inches	About 38 x 82 to 82 1/2 inches	Confirm framing and trim requirements.

These figures are planning estimates—not universal specifications. Rough openings can vary by manufacturer, frame design, jamb thickness, floor condition, door type, and hardware system. Always follow the instructions supplied with the actual door or frame kit.

Common Interior Door Thicknesses

Door Thickness	Typical Application	Hardware Considerations
1 3/8 inches	Common residential hollow-core and solid-core doors	Widely compatible with residential hinges, locks, and sliding hardware.
1 3/4 inches	Heavy, tall, custom, or higher-performance doors	Requires hardware, guides, locks, and frames made for the added thickness.
Custom thickness	Historic, architectural, or specialty doors	Confirm every component before ordering or cutting the door.

Thickness affects hinge size, latch backset, lock preparation, pocket-door guides, hanger plates, bifold pivots, bypass-door clearances, and jamb dimensions. Never assume that hardware made for one thickness will fit another.

Sizing Different Types of Interior Doors

Hinged or Swinging Doors

A hinged door needs enough wall and floor space to complete its swing. Consider furniture, switches, cabinets, fixtures, hallway width, and traffic flow when choosing its width and swing direction.

Double and French Doors

Double doors use two slabs in one opening. A 60-inch pair may use two 30-inch slabs, while a 72-inch pair may use two 36-inch slabs. Allowances for the center gap, jambs, astragal, stops, and hardware depend on the door system.

Pocket Doors

A pocket door slides into a framed cavity inside the wall. The wall must provide room for the doorway and the hidden pocket. As a general planning rule, a single-pocket-door rough opening is approximately twice the door width, plus the allowances required by the frame system.

Door height, thickness, weight, wall construction, and soft-close options must all match the selected frame kit.

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Bifold Doors

Bifold doors use hinged panels that fold as they move along a track. Two-panel and four-panel arrangements are common. The complete set is sized for the finished opening, with operating clearances determined by the track and pivot system.

Confirm opening width, opening height, number of panels, panel thickness, panel weight, folding direction, and track length.

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Bypass Doors

Bypass doors slide past one another on separate tracks. The combined panel width must be greater than the opening width so the doors overlap when closed.

The exact overlap depends on the number of panels, handles, guides, track spacing, door thickness, and the amount of access desired.

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Barn and Wall-Mount Doors

A wall-mounted sliding door usually needs to be wider and taller than the finished opening to provide adequate coverage. The wall beside the opening must also have enough clear space for the entire door.

Account for casing, baseboards, switches, outlets, handles, floor guides, track mounting height, and door-to-wall clearance.

Closet Doors

Closet openings may use hinged, bifold, bypass, or pocket doors. The best size and style depend on available floor space, wall space, closet depth, shelving position, and the amount of access required.

Custom and Oversized Doors

Wider, taller, and heavier doors place more load on the frame and hardware. Verify weight capacity, track length, hanger rating, wall support, door thickness, and installation clearances before ordering.

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How Wall Thickness Affects Door Sizing

Door jambs and concealed door systems must match the finished wall. A wall built with 2 x 4 framing will have a different finished thickness than a wall built with 2 x 6 framing.

Drywall thickness, plaster, tile, paneling, and other wall finishes can change the required jamb depth. Measure the complete finished wall rather than relying only on the lumber size.

Pocket-door frame kits must be selected for the correct wall construction. Hartford Building Products offers frame-kit configurations for both 2 x 4 and 2 x 6 walls.

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Allowing for Finished Flooring

Door height and bottom clearance should be planned around the finished floor—not only the subfloor. Flooring installed after the door is measured can reduce clearance or prevent the door from operating properly.

Include hardwood, tile, vinyl, laminate, or carpet thickness.
Include underlayment, padding, mortar, and transition profiles.
Provide enough clearance for the door to move freely.
Avoid excessive gaps that reduce privacy or sound control.
Check whether ventilation requirements affect the bottom gap.
Determine whether a threshold or floor transition will be installed.

Interior Floor Transitions

A hardwood interior threshold can provide a finished transition between rooms, bridge different flooring materials, or help manage modest differences in floor height.

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Door Width and Accessibility

A door's nominal width does not always equal its usable clear opening. Hinges, stops, jambs, handles, door thickness, and the opening angle can reduce the available passage.

When accessibility is a goal, begin with the required clear opening rather than selecting a door based only on its advertised slab width. A wider slab may be needed to produce the desired usable passage.

Accessibility rules and building codes vary by project type and location. Confirm current local requirements with the building department, designer, architect, contractor, or other qualified professional before framing or ordering materials.

For floor transitions along an accessible route, choose a threshold profile and height appropriate for the application.

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Door Size Checklist

Before ordering a door, frame, or hardware system, record the following:

Door slab width
Door slab height
Door thickness
Rough-opening width and height
Finished-opening width and height
Finished wall thickness
Flooring type and finished height
Door weight
Left- or right-hand operation
In-swing or out-swing direction
Single- or double-door configuration
Hinge, lock, pull, or track requirements
Required clear passage width
Available wall and floor space
Applicable building-code requirements

Common Door-Sizing Mistakes

Confusing Slab and Rough-Opening Sizes

A 30-inch door does not fit into a rough opening that is exactly 30 inches wide. The frame and installation space must be included.

Measuring Only Once

Openings can be wider at one point than another. Measure the top, center, and bottom, as well as both sides of the opening.

Ignoring Door Thickness

Locks, guides, hanger plates, pivots, and sliding-door systems may be designed for a specific range of door thicknesses.

Forgetting Finished Flooring

New flooring can reduce the bottom clearance and cause a swinging or sliding door to drag.

Overlooking Door Weight

Solid-core, hardwood, glass, oversized, and tall doors may require stronger frames, tracks, hinges, and hangers.

Ordering Hardware First

Select hardware only after confirming door type, dimensions, weight, thickness, wall construction, and operating arrangement.

Interior Door Size Questions

What is the most common interior door size?

An 80-inch height is common in residential construction. Frequently used widths include 28, 30, 32, and 36 inches, depending on the room and required access.

How wide should a bedroom door be?

Many bedroom doors are 30 or 32 inches wide. The best size depends on the home, required clear opening, furniture movement, and applicable building requirements.

How wide should a bathroom door be?

Bathroom doors commonly range from 24 to 32 inches wide. A wider door generally improves access, but the room layout and required clearances must also be considered.

Is a 32-inch door the same as a 32-inch clear opening?

No. The usable clear opening is normally smaller than the slab width because the open door, hinges, jambs, and stops occupy part of the opening.

Can an interior door be trimmed to fit?

Some doors can be trimmed within limits, but hollow-core and engineered doors may have narrow solid edges. Check the door manufacturer's trimming allowance before cutting.

How large is a pocket-door rough opening?

A single-pocket-door opening generally needs enough width for both the visible doorway and the hidden door pocket. Exact dimensions depend on the door width, frame design, hardware, and manufacturer instructions.

Should bypass-door panels equal the opening width?

The combined width of the panels normally exceeds the opening width so the doors overlap when closed. The required overlap depends on the track arrangement and number of panels.

Are bifold doors the same size as their opening?

Bifold sets are usually identified by their nominal opening size, but the actual panels are made slightly smaller to provide operating clearances for the track, pivots, hinges, and floor.

This guide provides general planning information. Door and rough-opening dimensions can vary by manufacturer, product, hardware system, wall construction, and local building requirements. Verify all measurements and product specifications before purchasing, cutting, or framing.