Door Sizes and Measuring
Accurate measurements help prevent ordering mistakes, installation delays, uneven gaps, and hardware problems. This guide answers common questions about standard door sizes, rough openings, door thickness, handing, replacement doors, and unusual openings.
```Know Which Measurement You Need
```Door size, finished opening, frame size, and rough opening are not the same measurement. Before ordering, identify whether you are replacing only the door slab, installing a complete prehung unit, or building a sliding, folding, or pocket-door system.
Door Slab Size
The actual width, height, and thickness of the door panel itself.
Finished Opening
The usable opening after the jamb, frame, flooring, and finished surfaces are installed.
Rough Opening
The framed opening in the wall before the door frame, jamb, or complete door system is installed.
Common Interior Door Sizes
```Interior doors are sold in many widths and heights. The sizes below are common residential examples, but availability varies by manufacturer, door style, construction, and project requirements.
| Measurement | Common Sizes | Typical Uses |
|---|---|---|
| Door Width | 18, 20, 22, 24, 26, 28, 30, 32 and 36 inches | Closets, bathrooms, bedrooms, offices and utility rooms |
| Door Height | 80 inches is common; 84 and 96 inches are also available | Standard, taller and architectural openings |
| Door Thickness | 1⅜ inches is common; 1¾ inches is used for many heavier doors | Residential, solid-core, specialty and heavy-duty applications |
| Double-Door Width | Based on the combined width of both door panels | French doors, double pocket doors and wide room openings |
What to Measure
- Door slab width at the top, middle, and bottom
- Door slab height at both vertical edges
- Door thickness at several locations
- Finished opening width and height
- Rough opening width and height when exposed
- Jamb depth or finished wall thickness
- Hinge locations and hinge sizes
- Lock or latch backset and bore location
- Floor clearance and finished flooring height
- Door swing or sliding direction
- Available wall space beside the opening
- Door weight for track or roller selection
Frequently Asked Questions
What are the most common interior door sizes?
Common residential door widths range from about 18 to 36 inches, often in 2-inch increments. An 80-inch height is widely used, while taller 84-inch and 96-inch doors are also available.
Are all interior doors a standard size?
No. Older homes, remodeled openings, custom construction, and architectural designs may use nonstandard widths, heights, or thicknesses. Always measure the actual opening before ordering.
What is the difference between nominal and actual door size?
A nominal size is the size used to identify or order the door. The actual panel may be slightly different because of manufacturing tolerances, required clearances, edge preparation, or trimming.
What is a rough opening?
A rough opening is the framed wall opening before the door frame or jamb is installed. It must provide space for the door unit, adjustment, shimming, fastening, and required clearances.
How much larger should a rough opening be than the door?
There is no single formula for every door system. Prehung, pocket, bifold, bypass, French, and specialty doors have different framing requirements. Use the instructions for the exact door or hardware system being installed.
Should I frame the opening before choosing the door?
Whenever possible, choose the door and obtain its installation specifications first. This reduces the risk of building an opening that is too narrow, too short, or incompatible with the frame and hardware.
What is the difference between a rough opening and a finished opening?
The rough opening is the unfinished framed space in the wall. The finished opening is the remaining usable space after jambs, tracks, trim, flooring, and other finished materials are installed.
What is the standard thickness of an interior door?
Many residential interior doors are 1⅜ inches thick. Heavier, oversized, solid-core, architectural, or specialty doors may be 1¾ inches thick or more.
Why is door thickness important?
Thickness affects hinges, locks, pulls, latches, tracks, guides, hangers, jamb preparation, and clearances. Hardware designed for one thickness may not fit another without different components.
Can a 1¾-inch door replace a 1⅜-inch door?
Sometimes, but the jamb, hinges, stops, lock preparation, track, and guides may need modification or replacement. Confirm that the frame and hardware can accept the thicker and often heavier panel.
What does door handing mean?
Door handing describes the side on which the hinges are located and the direction the door swings. Handing is especially important for prehung doors, locks, latches, and some specialty hardware.
How do I determine the handing of a hinged door?
Stand on the side where you can see the hinge pins when the door is closed. Hinges on the left indicate a left-hand door; hinges on the right indicate a right-hand door. Also confirm whether the door swings toward or away from you, because naming methods can vary.
Do pocket doors have handing?
Pocket doors do not use left-hand and right-hand swing labels in the same way as hinged doors. However, you must identify which side of the opening contains the pocket and the direction in which the door slides.
Do bifold and bypass doors have handing?
Bifold doors may be arranged to fold toward a particular side. Bypass doors require a planned front panel, rear panel, overlap, and direction of access. Record the arrangement before ordering hardware.
How do I measure an existing door for replacement?
Measure the door slab itself rather than the casing. Record width at three points, height at both sides, and thickness in several places. Also record hinge sizes, hinge locations, lock bore, backset, and swing direction.
Should I measure the door or the opening?
Measure both. The existing slab helps identify the replacement size, while the opening reveals whether the frame is square, level, and suitable for reuse.
How do I measure door width accurately?
Measure across the face of the slab at the top, middle, and bottom. Record all three dimensions. Differences may indicate that the door was trimmed or that the opening is out of square.
How do I measure door height accurately?
Measure from the top edge to the bottom edge on both sides of the slab. Do not include a sweep, guide, or removable bottom seal in the door-panel measurement.
How do I measure the jamb depth?
Measure from one finished wall surface to the other, excluding the casing. Include drywall, plaster, tile, paneling, or other permanent wall finishes.
Why should I measure in more than one location?
Openings and older doors are not always square or uniform. Measuring at several points reveals tapering, bowed jambs, uneven floors, and previous trimming.
How do I check whether an opening is square?
Measure diagonally from corner to corner in both directions. Matching diagonal measurements indicate a square opening. Also use a level to check the header and a level or plumb tool for both sides.
Should finished flooring be considered when measuring?
Yes. Hardwood, tile, carpet, underlayment, and thresholds affect the finished floor height and bottom clearance. Builders should establish the final floor level before making final door-height adjustments.
How much clearance should be left under an interior door?
Required clearance varies with the flooring, ventilation needs, door material, threshold, and local requirements. Follow the door manufacturer’s instructions and the project specifications.
How do I measure for a pocket door?
Record the desired clear opening, door width, height, thickness, weight, wall construction, finished wall thickness, and available wall space for the pocket. Use the frame-kit instructions to determine the required rough opening.
How much wall space does a pocket door need?
The wall must contain enough uninterrupted length for the door panel and pocket-frame components. Plumbing, wiring, ducts, switches, cabinets, and structural framing may reduce the available space.
How do I measure for double pocket doors?
Measure the full opening and determine the width of each panel. Allow for two wall pockets, a center meeting point, stops, guides, and any converging-door hardware specified by the system.
How do I measure for bifold doors?
Measure the finished opening width and height at several points. Record the number of panels, panel thickness, total door weight, and desired folding direction. Follow the hardware instructions for operating clearances.
How do I measure for bypass doors?
Measure the finished opening, track length, panel height, panel thickness, and available depth. Account for the required panel overlap so the doors cover the opening without leaving a visible gap.
How do I measure an arched or unusually shaped opening?
Record the width and height at several points and create a full-size template when required. Custom manufacturers may also request the arch rise, radius, spring line, or a digital drawing.
What should I do with a doorway that is not square?
Determine whether the problem is in the framing, jamb, floor, or surrounding structure. Correct the opening when practical rather than trimming a new door excessively to fit a distorted frame.
Can a standard door be trimmed to fit an unusual opening?
Some doors can be trimmed within manufacturer limits. Hollow-core, molded, fire-rated, glass, and engineered doors may have strict limits. Cutting too much can weaken the panel or remove required edge material.
When should I order a custom-size door?
Consider a custom door when the opening is unusually wide, tall, narrow, arched, historic, or difficult to modify. Custom doors may also be appropriate when matching existing architectural details.
What measurements should builders confirm before ordering?
Confirm rough-opening width and height, slab size, jamb depth, wall thickness, handing, floor elevation, hinge preparation, lock preparation, door weight, hardware capacity, trim, and required clearances.
Replacement Door Measuring Checklist
| Measurement | Where to Measure | Why It Matters |
|---|---|---|
| Slab Width | Top, middle and bottom of the door | Identifies tapering or previous trimming |
| Slab Height | Along both vertical edges | Reveals uneven floors or altered edges |
| Thickness | At the top and both side edges | Determines hardware and jamb compatibility |
| Hinge Locations | From the top of the door to each hinge | Helps align a replacement slab with the jamb |
| Lock Bore | From the top and edge of the door | Helps match the existing latch and strike |
| Backset | From the door edge to the center of the bore | Determines lockset compatibility |
| Jamb Depth | Between finished wall faces | Helps size a prehung frame correctly |
| Floor Clearance | Between the slab and finished floor | Prevents rubbing and allows planned ventilation |
Matching Door Measurements to Hardware
```Sliding and folding door hardware must match the door’s width, height, thickness, weight, wall construction, and operating arrangement. Hartford Building Products offers hardware for pocket, bifold, and bypass door projects.
Pocket Door Frame Kits
Select a frame kit by wall construction, single- or double-door arrangement, door size, thickness, and preferred operating features.
Pocket Door Tracks and Rollers
Match tracks, hangers, guides, stops, and soft-close components to the panel dimensions and total door weight.
Bifold Door Hardware
Record finished-opening dimensions, panel thickness, panel count, folding direction, and weight before selecting the track and pivots.
Bypass Door Hardware
Measure the opening, panel overlap, door thickness, panel height, track length, and available depth for the parallel tracks.
Pulls and Locks
Door thickness, bore preparation, backset, and edge dimensions must suit the selected pull, privacy lock, or passage hardware.
Technical Planning
Review the product dimensions and installation instructions before framing the wall or modifying an existing opening.
Measure First and Order Second
```Confirm the door slab, opening, wall, floor, hardware, and operating direction before placing an order. A few extra measurements can prevent costly changes after construction begins.