What Are Door and Frame Sizes?
Door and frame sizes refer to the standardized dimensions of a door slab and its surrounding frame, including width, height, and thickness. For B2B buyers, these dimensions determine compatibility with wall openings, compliance with local building codes, and the ease of installation across multiple units. The two most critical numbers are the door slab width and height, followed by the frame’s jamb depth, which must match the wall thickness.
Standardization exists so that manufacturers, distributors, and contractors can specify products without custom engineering for every project. In the U.S. market, dimensions are typically expressed in inches, while many international projects use metric. Understanding both systems prevents costly specification errors in global sourcing.
Standard Door and Frame Size Charts
The table below lists common standard door slab sizes, their corresponding frame dimensions, and typical rough openings. Rough opening means the framed gap in the wall, which must be larger than the door unit to allow for shimming and leveling.
| Door Type | Door Width (in) | Door Height (in) | Frame Width (in) | Frame Height (in) | Rough Opening Width (in) | Rough Opening Height (in) |
|---|---|---|---|---|---|---|
| Interior single | 28 | 80 | 30.5 | 81.5 | 32 | 82.5 |
| Interior single | 30 | 80 | 32.5 | 81.5 | 34 | 82.5 |
| Interior single | 32 | 80 | 34.5 | 81.5 | 36 | 82.5 |
| Interior single | 36 | 80 | 38.5 | 81.5 | 40 | 82.5 |
| Exterior single | 32 | 80 | 34.5 | 81.5 | 36 | 82.5 |
| Exterior single | 36 | 80 | 38.5 | 81.5 | 40 | 82.5 |
| Exterior single | 36 | 84 | 38.5 | 85.5 | 40 | 86.5 |
| Double (each leaf) | 30 | 80 | 64.5 | 81.5 | 66 | 82.5 |
| Double (each leaf) | 36 | 80 | 76.5 | 81.5 | 78 | 82.5 |
Metric equivalents for the most common sizes: a 30-inch door equals 762 mm; 32-inch equals 813 mm; 36-inch equals 914 mm. Standard heights of 80 inches equal 2032 mm, and 84 inches equal 2134 mm. Frame widths add roughly 2 to 2.5 inches to the door width, and frame heights add about 1.5 inches.
The standard interior door height in the U.S. is 80 inches (6 feet 8 inches). The most common widths are 30, 32, and 36 inches. For exterior entrances, 36 inches wide by 80 inches tall is the dominant specification, though 84-inch heights are increasingly common in higher-end residential and commercial projects.
How to Measure Door and Frame Sizes Correctly
Accurate measurement requires distinguishing between the door slab, the frame, and the rough opening. Measuring the wrong element leads to incorrect ordering, especially when specifying pre-hung units versus slab-only doors.
Door slab measurement. Measure the door itself, excluding any frame or trim. Width is measured across the door face; height from the top edge to the bottom edge. Do not include weatherstripping or sweep attachments in these numbers.
Frame measurement. The frame width is the distance between the inside edges of the left and right jambs. Frame height is from the top of the head jamb to the bottom of the threshold or sill. For unfinished frames without a threshold, measure to the subfloor.
Rough opening measurement. The rough opening is the gap in the wall framing. Measure its width at three points: top, middle, and bottom. Use the narrowest measurement. Do the same for height, measuring from the subfloor to the underside of the header. The rough opening must be about 2 inches wider and 2.5 inches taller than the door slab to allow for shims, leveling, and the frame itself.
Jamb depth. Measure the thickness of the wall from the interior drywall face to the exterior sheathing or siding. Standard residential walls built with 2×4 studs produce a jamb depth of about 4.5 inches. Walls with 2×6 studs require jambs around 6.5 inches deep. If the jamb is too shallow, the frame will not reach the wall surface; if too deep, it protrudes and complicates trim installation.
When measuring an existing opening for replacement, account for flooring thickness. If new flooring raises the finished floor level, the door height must be adjusted accordingly. A common error is ordering an 80-inch door when the finished floor will reduce the effective opening to 79 inches.
Door and Frame Sizes by Application
Residential interior. Standard interior doors range from 28 to 36 inches wide, with 30 and 32 inches being the most common for bedrooms and bathrooms. Hallways and closets often use 28-inch doors. The 80-inch height dominates. Frame jambs for 2×4 walls are typically 4.5 inches deep.
Residential exterior. Entry doors are almost always 36 inches wide and 80 inches tall for single-family homes. Some premium projects specify 84-inch heights. Exterior frames require deeper jambs to accommodate insulation and sheathing, and thresholds add to the overall frame height. Double entry doors typically use two 36-inch leaves, creating a 72-inch clear opening.
Commercial. Commercial doors are governed more strictly by accessibility codes. The International Building Code (IBC) and the Americans with Disabilities Act (ADA) require a minimum 32-inch clear opening for doorways. Because the clear opening is measured with the door open at 90 degrees, the door slab itself must be wider than 32 inches. A 36-inch door slab typically provides the required clearance, depending on hinge and stop placement. Commercial doors are commonly 36 inches wide and 84 inches tall, with 40-inch-wide frames.
Custom and non-standard openings. Older buildings often have non-standard openings due to settling, previous renovations, or non-modular construction. In these cases, the practical approach is to measure the actual rough opening and order a custom frame that fits, rather than attempting to force a standard unit into an irregular gap. Custom sizing adds lead time and cost but avoids on-site modification.
Special Cases: Oak Frame Doors and A-Frame Doors
Oak frame doors are a distinct category in the U.S. and U.K. markets. These are not standard slab doors fitted with oak trim; they are complete door assemblies built from solid oak, typically with a frame that is deeper and heavier than standard softwood or aluminum frames. An oak frame door has frame dimensions that exceed the door slab by a wider margin, often 4 to 6 inches in width, because the frame itself is a structural and decorative element.
For B2B buyers specifying oak frame doors, the critical measurement is the overall frame size, not the door leaf size. A 36-inch oak door leaf may sit within a frame that is 44 inches wide overall. This affects rough opening requirements significantly. Verify whether the supplier quotes the leaf size or the frame size, as confusing the two is a frequent sourcing error.
An “A frame door” refers to a door installed within an A-frame structure, where the opening is not rectangular but angled to match the roofline. This is common in chalet-style buildings, cabins, and certain architectural designs. Sizing for an A-frame door is not governed by standard tables because the side jambs are angled rather than vertical. The door leaf itself may be a standard rectangle, but the frame must be custom-fabricated to fit the angled opening. The head jamb may also be angled if the door follows the roofline.
When specifying an A-frame door, provide the angle of the side jambs relative to vertical, the width at the base of the opening, the width at the top, and the height. Suppliers need these dimensions to fabricate the frame correctly. Standard door sizes do not apply to the frame in this scenario, though the door leaf can often be a standard size if the opening width permits.
Related Considerations for B2B Buyers
Frame material affects dimensional tolerance. Wood frames are typically fabricated to within 1/8 inch of specified dimensions but can expand and contract with humidity. Aluminum frames, common in commercial and exterior applications, hold tighter tolerances and are less affected by moisture. Thermal-break aluminum frames add insulation but increase the overall frame depth, which affects jamb requirements.
Building codes vary by region. The International Residential Code (IRC) requires a minimum 36-inch clear width for egress doors in residential occupancies. However, local amendments can change these requirements. Always verify the applicable code for the project’s jurisdiction rather than assuming national standards apply universally. Accessibility requirements under ADA are federal in the U.S., but state and local codes may impose additional requirements.
Rough opening sizes vary by manufacturer. The figures in the table above are typical for wood and aluminum frame systems. Some systems, particularly European-style system windows and doors, use different frame profiles that require larger or smaller rough openings. When sourcing from a specific manufacturer, request their installation instructions and rough opening specifications rather than relying on generic tables.
Metric versus imperial specification. For international projects, confirm whether the supplier quotes metric or imperial dimensions. A 30-inch door is 762 mm, but a 750 mm door is not the same size. Rounding errors in conversion lead to ill-fitting frames and costly rework. Specify the measurement system clearly in the purchase order.
Final Thoughts and Expert Guidance
Standard door and frame sizes exist to simplify specification, but they are not universal. The correct size depends on the application, the wall construction, the frame material, and the applicable building codes. For B2B buyers, the most reliable approach is to measure the actual rough opening, confirm the jamb depth required by the wall thickness, and then match those figures against the manufacturer’s specifications.
As a manufacturer, our approach to this is straightforward. We produce thermal-break aluminum doors and windows, system windows, and custom villa doors and windows. Because we supply directly from our factory, we can adjust profile structures and fittings to match local building codes in your target market. If your project requires non-standard frame sizes, an oak frame door, or an A-frame installation, we can fabricate to your exact measurements rather than forcing a standard unit into the opening.
We also provide full customs documentation, packing lists, and proforma invoices for international shipments, with both FCL and LCL options. If you are specifying doors for a construction project and need verified dimensions for your openings, contact our team with your rough opening measurements and wall construction details.
