Standard Door Sizes & Configurations: The Complete Measuring Guide

Every hardware return starts the same way: a threshold, astragal, or hinge that was ordered to fit a door size that turned out to be slightly different than assumed.

Doors look standardized, and mostly they are - but "standard" covers a range, not one fixed number, and the difference between a 30 inch and 32 inch door, or a 1-3/8 inch and 1-3/4 inch thickness, is exactly the kind of detail that determines whether your hardware fits the first time.

This guide breaks down the actual standard sizes - residential, commercial, and double-door configurations - so you're measuring against real industry numbers, not guesswork.

Door Size vs. Rough Opening vs. Clear Opening

These three measurements get mixed up constantly, and each one means something different:

• Door size is the nominal dimension of the door slab itself - the number on the box.
• Rough opening is the framed hole in the wall before the door and jamb are installed, sized larger than the door to allow for the frame and shimming.
• Clear opening is the actual usable passage width once the door is installed and open - always smaller than the door size itself, once you subtract the frame, stop, and hinge offset.

A 36 inch door, for example, typically yields only about 32 to 34 inches of clear opening width - a distinction that matters directly for ADA accessibility calculations, which are based on clear opening, not door size.

Standard Residential Door Sizes

Exterior Doors

• Width: most commonly 36 inches, with 30 and 32 inch stock sizes also available
• Height: 80 inches standard, with 96 inch tall entries increasingly common in newer construction
• Thickness: 1-3/4 inches

Interior Doors

• Width: 24 inches (closets), 28 to 30 inches (bathrooms and bedrooms), 32 to 36 inches (accessible or primary rooms)
• Height: 80 inches standard
• Thickness: 1-3/8 inches, though wider or taller interior doors sometimes step up to 1-3/4 inches for added rigidity

Standard Commercial Door Sizes

Commercial doors follow a narrower, more standardized range than residential doors, driven largely by accessibility and building code requirements.

• Most common size: 36 inches wide by 84 inches tall
• Thickness: 1-3/4 inches is standard, with 2-1/4 inches used in specialized high-security or heavy commercial applications
• Accessibility: 36 inch width is widely used specifically because it supports ADA clear-opening requirements alongside comfortable movement of people and equipment

Because commercial doors see far higher daily traffic, hardware selected for them should match commercial-grade standards, not just the door's dimensions. Our guide on commercial vs. residential hardware covers this distinction in more detail.

Rough Opening Sizing

The rough opening is the unfinished, framed space in the wall - it needs to be larger than the door unit itself to leave room for the frame, shims, and leveling.

As a general formula: rough opening width equals door width plus about 2 inches, and rough opening height equals door height plus about 2 to 2.5 inches. Always confirm against the specific door or frame manufacturer's requirements before framing, since these numbers can shift slightly by product line.

Double Door and Specialty Configurations

Double doors, French doors, and sliding systems don't follow the same single-leaf math, since total opening width is split across two panels meeting at a shared center point.

• Double/French doors: commonly span 60 to 72 inches total width or more, split evenly across two door leaves
• Sliding patio doors: often around 80 inches tall by 72 inches wide, though wider multi-panel configurations are common

On any double-door opening, the hardware at the center seam and the base becomes more critical, not less - that shared meeting point is exactly where T-astragals and a properly sized, rail-integrated threshold matter most. Total opening width, not per-panel width, is what determines the correct threshold length to order.

Why Getting the Size Right Matters for Your Hardware

Every hardware category on a door depends on an accurate measurement in a slightly different way:

• Thresholds are ordered by total opening width, not door slab width - critical on double and sliding doors especially.
• Astragals are sized to door height, and need to match the full-height door leaf to seal the meeting stile without gaps at the top or bottom.
• Hinges depend on door thickness and weight, not just height - a door outside a hinge's rated thickness range won't mortise or seat correctly. Our concealed hinge line, for example, is built for doors thicker than 35mm.
• Door bottoms are cut to door width, so an accurate width measurement avoids trimming too short.

How to Measure Your Door Correctly

1. Measure the door slab width at the top, middle, and bottom - use the smallest number if they differ.
2. Measure height from the top edge to the bottom edge on both the left and right sides, using the longer measurement.
3. Check thickness at the door's edge directly, rather than assuming based on interior or exterior use.
4. For double doors, measure total combined opening width, not each leaf separately.
5. If replacing hardware only, measure existing hardware cutouts and dimensions rather than the door itself.

FAQ

Have more questions? Visit our full FAQ page.

Final Thoughts: Measure Twice, Order Once

Standard door sizes give you a reliable starting point, but "standard" still spans a real range - in width, height, and thickness alike. The fastest way to avoid a hardware return is to measure the actual door or opening directly, rather than assuming it matches the most common number on this page.

Once you've got accurate measurements in hand, matching the right threshold, astragal, hinge, or door bottom becomes a straightforward lookup instead of a guess.