Standard Indoor Door Sizes: A Complete Buying Guide

Key Takeaways: Standard Indoor Door Sizes at a Glance

If you are replacing doors or building new interior walls, the most common standard interior door sizes are 24, 28, 30, 32, and 36 inches in width, with 80 inches (6’8″) being the near-universal height in the US. In metric regions, the typical widths are 600, 700, 800, and 900 mm, with heights of 2000 or 2100 mm. Door thickness for interior slab doors is usually 1¾ inches (35–45 mm).

However, these “standard” sizes are not a single global rule. They vary by region, by manufacturer, and by whether you are buying a door slab (the door only) or a pre-hung unit (door plus frame). This guide explains the differences, how to measure correctly, and when custom sizing is the smarter choice.

Indoor Door Sizes Explained: Types, Dimensions, and Standards

Standard Sizes by Region

The most common mistake buyers make is assuming a door size from one country will fit a frame in another. Here is the breakdown:

• United States (imperial): Standard interior door widths are 28″, 30″, 32″, and 36″. The most common for bedrooms is 30″–32″; bathrooms often use 28″–30″. Standard height is 80″ (6’8″). Some newer homes use 84″ (7’0″) doors for a more modern proportion. Thickness is typically 1¾” for slab doors.
• United Kingdom (metric): Standard internal door widths are 762 mm (30″), 838 mm (33″), and 914 mm (36″). The standard height is 1981 mm (78″) or 2032 mm (80″). Thickness is typically 35 mm or 40 mm.
• European Union (metric): Common widths are 600 mm, 700 mm, 800 mm, and 900 mm. Standard height is 2000 mm, with 2100 mm increasingly common in new construction. Thickness is usually 40 mm.

Nominal vs. actual size matters. A door labeled “30 inches” is not exactly 30.000 inches. A 30″ slab door typically measures 29½” wide to allow for a 1/8″ gap on each side plus the jamb clearance. Similarly, a metric 800 mm door is often 794 mm or 798 mm wide. If you are ordering a slab to fit an existing frame, always measure the actual door, not the label.

Door Slab vs. Pre-Hung Unit

This is the first decision that affects everything else, including sizing.

• Door slab: Just the door panel, with no frame, hinges, or pre-drilled holes. You reuse your existing frame. You must match the slab size to the existing frame’s rough opening and jamb depth. This is the cheaper route if your frame is in good condition.
• Pre-hung unit: The door slab comes already fitted into a jamb (frame) with hinges installed. You set the entire unit into the rough opening. This is the standard for new construction and for replacing a damaged frame. Pre-hung units require you to specify the rough opening size, which is larger than the door itself.

For a pre-hung door, the rough opening is the wall gap you build before installing the unit. A typical rule: rough opening width = door width + 2 inches, and rough opening height = door height + 2½ inches. But this varies with jamb thickness and manufacturer tolerances, so always confirm with the supplier’s spec sheet.

Door Types and Their Sizing Logic

• Slab doors: Sizing is straightforward—match the slab to the existing frame.
• Pre-hung doors: Sizing involves the door plus jamb. The jamb depth must match your wall thickness (see below).
• Bifold doors: Used for closets and laundry rooms. Standard widths are 24″, 30″, 32″, and 36″, with the door split into two panels that fold. Height is typically 80″ or 96″ for taller closets.
• Pocket doors: These slide into a wall cavity. The rough opening must be roughly twice the door width plus framing. Standard door widths are the same as hinged doors (30″–36″), but the wall cavity depth is a critical constraint—you cannot install a pocket door in a thin partition wall.
• Sliding barn doors: These are surface-mounted and do not require a rough opening. They are sized to cover the doorway plus 2–4 inches on each side for overlap. Standard widths for the door panel itself are 30″–42″.

Jamb Depth and Wall Thickness

This is where most sizing errors happen. The jamb (the frame the door sits in) must match the thickness of your finished wall. Common wall thicknesses:

• 2×4 framing with ½” drywall: About 4⅞” finished thickness. This needs a 4⅞” jamb.
• 2×6 framing with ½” drywall: About 6⅞” finished thickness. This needs a 6⅞” jamb.

If you order a pre-hung door with the wrong jamb depth, it will either protrude from the wall or sit recessed, requiring shims and trim work to hide the gap. For slab doors, the jamb is already in place, so you only need to match the door’s thickness (usually 1¾”) to the frame’s groove.

White Internal Doors and Other Popular Styles: What to Consider

White is the dominant finish for interior doors because it is neutral, brightens hallways, and works with any trim color. But “white door” covers several distinct products, and the differences matter for sizing and durability.

White Door Finishes and Materials

• Solid white doors (solid core): These have a solid interior—either engineered wood, particleboard, or MDF core—with a white factory finish. The solid core makes them heavier, denser, and better at blocking sound. They are the best choice for bedrooms, home offices, and bathrooms where privacy matters. Sizing is identical to hollow core doors, but the weight affects hinge requirements.
• White door slab (hollow core): These have a honeycomb cardboard or foam interior with a thin MDF or wood veneer skin. They are lightweight, inexpensive, and easy to install. The trade-off is poor sound insulation and a “hollow” feel when knocked. They are fine for closets and utility rooms.
• White internal doors with factory primer: Many “white” doors actually ship with a white primer, not a finished paint. The primer is meant to be painted over with your chosen white. Factory-finished doors (painted at the factory) are more expensive but save labor and give a consistent, durable surface.

Paint Types and Maintenance

Factory-finished white doors typically use polyurethane or polyester paint, which is baked on for durability. Field-painted doors (primed at the factory, painted on site) are more vulnerable to chipping and yellowing over time.

For high-traffic areas, specify a door with a factory-applied UV-cured or polyurethane finish. It resists scuffs, cleans with a damp cloth, and does not yellow as quickly as oil-based paints. Matte or eggshell finishes hide fingerprints better than gloss but are harder to clean. Semi-gloss is the practical middle ground for white doors.

Solid White vs. Hollow Core: The Real Trade-off

If you are buying for a rental property or flipping a house, hollow core white doors keep costs down. If you are building or renovating your own home, solid white doors are worth the premium for the feel and acoustic performance alone.

Comparison Table: Door Sizes and Types

Prices vary significantly by material (solid wood > MDF > hollow core) and finish (factory-painted > primed). The table reflects relative cost tiers, not absolute prices, which fluctuate with lumber and MDF costs.

How to Choose the Right Door Size: A Practical Guide

Step 1: Measure the Existing Frame (for Slab Replacement)

• Measure the width at three points: top, middle, and bottom of the frame opening. Use the narrowest measurement.
• Measure the height at both left and right sides, from the floor to the top of the frame. Use the shorter measurement.
• Measure the thickness of the existing door (not the frame). Standard is 1¾”, but some older homes have 1⅜” doors.
• Check for square. Use a level on the frame sides. If the frame is out of square by more than ¼”, a slab door may not fit properly; you will need to plane the door or adjust the frame.

Important: Measure the frame opening, not the existing door. Doors can be trimmed or swollen, so the frame is your reference.

Step 2: Measure the Rough Opening (for Pre-Hung Installation)

• Width: Measure the rough opening from stud to stud at three heights. Use the narrowest.
• Height: Measure from the subfloor (not the finished floor) to the top of the header.
• Wall thickness: Measure the total wall depth at the opening (drywall to drywall).

Then subtract for the jamb and clearance: typically ¾”–1″ from the width and ½”–¾” from the height to get the maximum door size that will fit.

Step 3: Consider the Flooring

If you are installing new flooring, the finished floor height will reduce the door clearance. A door that fits now may scrape after carpet or tile is installed. Plan for a ½”–¾” gap under the door, and account for flooring thickness when measuring the rough opening height.

Step 4: Decide on Custom Sizing

Non-standard openings are common in older homes, basements, and custom builds. If your opening is, say, 31½” wide, you have two options:

• Order a custom slab door cut to your exact dimensions. This is the cleanest solution and avoids the gap-filling shims and trim that come with using a 30″ door in a 31½” opening.
• Use a standard door with filler strips. This is cheaper but looks unprofessional unless you are skilled with trim work.

Custom sizing is also the answer for:

• Wheelchair access: A 36″ door is the minimum for ADA-compliant pathways in the US. For tight turns, 42″ or wider may be needed.
• High ceilings: 84″ or 96″ doors can make a room feel more spacious and are increasingly popular in luxury builds.
• Older homes: Pre-1950s homes often have odd-sized openings that do not match modern standards.

Step 5: Verify Building Codes and Clearances

Building codes are regional, so do not rely on a universal rule. In the US, the International Residential Code (IRC) requires a minimum 32″ clear opening for doors in accessible pathways—but this applies to new construction, not necessarily replacements. In the UK, Part M of the Building Regulations specifies minimum door widths for accessibility in new dwellings. Always check your local code before ordering, especially for basement egress doors or doors in accessible routes.

Frequently Asked Questions About Indoor Door Sizes

What are the standard interior door sizes in inches and centimeters?

In the US: widths of 28″, 30″, 32″, and 36″ (71, 76, 81, 91 cm), height of 80″ (203 cm). In metric regions: widths of 600, 700, 800, and 900 mm (24″, 28″, 32″, 36″), heights of 2000 or 2100 mm (79″ or 83″). Thickness is typically 1¾” (45 mm) in the US and 35–40 mm in Europe.

How do I measure for a new interior door?

For a slab door, measure the frame opening at three widths and two heights, use the smallest dimensions, and measure the existing door’s thickness. For a pre-hung door, measure the rough opening (stud to stud, subfloor to header) and the wall thickness. Always measure twice; door sizes are unforgiving.

What is the difference between a door slab and a pre-hung door?

A door slab is just the door panel—you reuse your existing frame. A pre-hung unit includes the door, jamb, and hinges, and is installed as one piece into a rough opening. Slab replacement is cheaper and simpler if the frame is sound; pre-hung is necessary for new walls or damaged frames.

Can I get custom-sized white internal doors?

Yes. Custom sizing is standard in the industry for non-standard openings. You specify the exact width, height, and thickness, and the manufacturer cuts the door to your dimensions. This is common for older homes, high ceilings, and accessibility requirements. Custom white internal doors are available in both solid core and hollow core construction.

What are the benefits of solid white doors over hollow core doors?

Solid white doors are heavier, block sound significantly better, resist dents and warping, and feel more substantial when closed. They are the right choice for bedrooms, bathrooms, and offices. Hollow core doors are lighter, cheaper, and easier to install, but they transmit sound and dent easily. For a closet or utility room, hollow core is a sensible budget choice.

Are white door slabs suitable for exterior use?

Generally, no. White interior door slabs are not designed for exterior exposure. They lack the weather sealing, insulation, and structural reinforcement needed for exterior doors. If you need a white door for an exterior opening, you need a dedicated exterior door unit with proper weatherstripping, thermal break, and threshold. Using an interior slab outside will lead to warping, water damage, and energy loss.

What sizes are available for indoor-outdoor living doors?

Indoor-outdoor living doors—typically large sliding or folding glass systems that connect living spaces to patios or gardens—are not governed by the same standards as interior doors. Common configurations use panels that are 30″–40″ wide and 80″–96″ tall, but the total opening can be 8 to 20 feet wide. These are almost always custom-engineered for the specific opening. The key specification is the structural header above the opening, which must support the weight of the glass and framing. You will need a structural engineer or a specialized manufacturer for these systems.

Additional Considerations: Factory Doors, Exterior White Doors, and Indoor-Outdoor Living Doors

Factory Door Supply: What It Means for Buyers

Buying doors directly from a factory changes the value equation. When you purchase from a distributor or retail store, you pay for their inventory, storage, and markup. A factory-direct purchase eliminates the middleman, but it also shifts responsibilities: you are specifying the product yourself, and you are relying on the factory’s quality control.

The practical advantages of factory-direct doors include:

• Custom sizing without custom pricing. Factories can adjust dimensions without the surcharge a distributor might add.
• Consistent finish. Factory-applied white finishes are more uniform than field painting.
• Full documentation. A factory can provide packing lists, proforma invoices, and customs documents—essential for international orders.
• Logistics flexibility. Factories can ship full container loads (FCL) or less-than-container loads (LCL), depending on your order volume.

The trade-off is lead time. Factory orders are manufactured to order, so you wait weeks rather than days. Plan ahead for renovation timelines.

White Door Exterior vs. Interior

White is a popular finish for exterior doors in modern architecture, but the product is fundamentally different from an interior white door. Exterior white doors must have:

• A thermal break in aluminum frames or insulated cores in wood/steel doors.
• Weatherstripping around all edges to prevent air and water infiltration.
• UV-resistant finish to prevent yellowing and chalking.
• Reinforced construction to resist forced entry and wind loads.

If you are considering a white door for an exterior application, the interior door standards do not apply. You need a purpose-built exterior unit, and the sizing is dictated by the rough opening and the door’s structural requirements, not by interior door conventions.

Indoor-Outdoor Living Doors: Sizing and Structural Considerations

Transitional spaces—sunrooms, patios, and garden rooms—require doors that blur the line between inside and outside. These are typically large-format sliding or folding systems. The sizing logic is different:

• Panel width: Most systems use panels from 30″ to 40″ wide. Wider panels mean fewer frames and more glass, but they also require heavier hardware and thicker framing.
• Panel height: Standard residential heights are 80″–96″. Taller panels (up to 120″) are possible but require specialized engineering.
• Total opening width: This is the sum of all panels. A 12-foot opening with four 36″ panels is a common configuration.

The critical factor is the header above the opening. It must support the weight of the door system plus any loads above (roof, second story). For openings wider than 8 feet, a structural engineer should calculate the header size. The door manufacturer will provide the weight and load specifications, but the building structure must accommodate them.

Performance testing matters. For indoor-outdoor doors, the manufacturer should provide test data for air-tightness, water-tightness, and wind resistance. These are not optional extras—they determine whether the door performs in real weather conditions. A door that fails the water-tightness test will leak during heavy rain regardless of how it looks.

Get a Free Quote for Custom Indoor Doors

When you are ready to move from planning to purchasing, the key is working with a manufacturer that can execute your specifications precisely. As a door and window factory, our approach is straightforward: you provide your measurements or drawings, and we manufacture the doors to fit.

Here is how we meet the standards discussed in this guide:

• Direct factory supply. We manufacture solid wood doors, thermal-break aluminum doors, and system windows, and we supply them directly without distributor markup. Your quote reflects factory pricing, not retail margins.
• Full customization. We adjust size, color, glass, and hardware to match your project. If your opening is 31½” wide or your ceiling is 84″ tall, we build the door to those dimensions—no filler strips, no compromises.
• Pre-shipment inspection. Every order is tested for air-tightness, water-tightness, and wind resistance before it leaves the factory. For indoor-outdoor living doors, this is the data you need to verify performance.
• International logistics. We handle FCL and LCL shipments with full customs documentation, including packing lists and proforma invoices. We also adjust profile structures and fittings to match local building codes in your target market.

We work with contractors, builders, and importers on bulk supply projects, and we support OEM and ODM orders. If you are comparing white internal doors, solid white doors, or custom-sized door slabs, send us your opening dimensions and we will confirm the exact product that fits.

Get a Free Quote

For a faster response, contact our team directly on WhatsApp or email Leon Wu at cyxs001@gmail.com. Include your measurements, quantities, and any drawings, and we will respond with a detailed quotation and production timeline.