| Quick Answer: A door labeled by its nominal size is never exactly that size. A "36-inch" door measures about 35-3/4 inches wide; a "30-inch" door is about 29-3/4 inches. Height works the same way: an "80-inch" door is typically 79-1/2 inches tall. For hidden doors, these fractions matter more than most people expect, because a 3/16-inch reveal gap is the difference between a wall that disappears and one that obviously has a door in it. |
By Jeremy Barker, Founder and CEO, Murphy Door®
Published 2026-10-01
Here's the thing about door sizes: the label on the door is not the size of the door. It never has been. The industry calls these "nominal" dimensions, and the gap between what the label says and what a tape measure shows has caused more installation headaches than almost any other single variable we hear about. We've been building hidden doors in Ogden, Utah since 2012, and week after week someone calls 888-458-5911 to tell us their "36-inch opening" won't accept a 36-inch door. It will. It's just that neither number means what they think it means.
This guide exists to fix that. I'll walk you through exactly what every common door size actually measures, what your rough opening needs to be, and where things get more precise when you're ordering a Murphy Door® hidden door instead of a standard slab. Getting these numbers right isn't just about fit. It's about whether the wall looks like a wall.
A pair of Murphy Door® hidden bookcase doors installed flush in a home office wall. When sizing is dialed in correctly, painted doors like these vanish completely into the surrounding wall plane, with no visible gap or frame break to give them away.
Is a 36-Inch Door Actually 36 Inches Wide?
Are 36-inch doors really 36 inches?
No. A nominal 36-inch door is about 35-3/4 inches wide. Door manufacturers use nominal sizing, the label describes a rounded planning dimension, not the finished measurement. The actual door slab runs 1/4 inch under the nominal width on most standard residential doors.
What is the actual clear width of a 36-inch door?
Clear width is the usable passage after the door swings open and the stops are in place. For a 36-inch door, clear width typically lands around 34 inches once you account for the door stop and the hinge leaf. If you need a specific clear width for accessibility reasons, work backward from that number to find your door size. Don't start from the nominal label and hope for the best.
Do you have to order a 36-by-83-inch door?
Not necessarily. Standard doors come in 80-inch and 84-inch heights. The 83-inch figure shows up in some pre-hung units because the frame adds height, but the door slab itself is usually 80 inches. If you see "36x83" on a pre-hung unit, that's often the frame dimension, not the slab. Confirm which measurement is being quoted before you order anything.
Are 30-inch doors actually 30 inches?
Same rule applies. A nominal 30-inch door measures about 29-3/4 inches. Plan your rough opening accordingly.
What Is the Actual Size of a 24x80 Door?
Is 24 inches a standard door size?
It is, but it's on the narrow end of residential use. You'll find 24-inch doors on closets and utility spaces. The actual slab runs about 23-3/4 inches wide by about 79-1/2 inches tall. For a Murphy Door® hidden door in a 24-inch opening, we'd want to talk through whether the space justifies that size. Narrower openings limit how much you can load onto a bookcase face before weight distribution becomes a real concern.
Is an 80-inch door actually 80 inches?
No. The slab is typically 79-1/2 inches. Like width, height follows the same nominal convention. When you see "80-inch door," you're looking at a slab that's a half-inch shorter. This matters when you're calculating reveal gaps and floor clearance on a swinging hidden door.
What is the actual size of a 32x80 door?
Actual slab dimensions run about 31-3/4 inches wide by 79-1/2 inches tall. Rough opening for that door is typically 34 inches wide by 82 inches tall, to allow for the frame, shimming, and clearance.
What does a 36x80 door actually measure?
The slab is about 35-3/4 inches wide by 79-1/2 inches tall. Rough opening target is generally 38 inches wide by 82 inches tall. Those two extra inches in width give you room for the jamb on both sides plus shim space. If you're installing a Murphy Door® hidden door in that opening, we ship pre-cut shim stock with every order so your contractor can dial in the fit without improvising.
Is 32 Inches a Standard Door Size?
Are 32-inch doors actually 32 inches?
No. A nominal 32-inch door slab measures about 31-3/4 inches. Standard residential widths run 24, 28, 30, 32, 34, and 36 inches. Among those, 32 and 36 are the most common for bedroom and main passage doors.
Will a 30-inch door fit in a 32-inch opening?
It will, with the right framing, but that's not how you want to approach it. A door that's undersized for its opening needs filler material or extended jamb work to close the gap cleanly. For hidden doors, an undersized slab in an oversized opening is a near-guarantee that your wall won't look like a wall. Size the door to the opening, not the other way around.
What size door do I need for a 32-inch opening?
If your rough opening is 32 inches wide, you need a door slab around 29-3/4 to 30 inches to allow for the frame and shimming. The general rule: rough opening width equals the nominal door width plus 2 inches. So a 30-inch door needs a 32-inch rough opening. That two-inch buffer covers the jamb on each side and shim stock.
Can an exterior door be 32 inches?
Yes, though 36 inches is more common for exterior primary entries, and local building codes often specify minimum widths for egress and accessibility. Check your local requirements for specifics. Murphy Door® ships hidden doors in a range of widths, call us at 888-458-5911 if your situation doesn't match a standard size and we'll walk through the custom options.
Our unassembled French bookcase hidden door shown open. French door sizing follows the same nominal rules as single doors, but now you're coordinating two slabs, a center meeting stile, and a shared rough opening. Getting the width right matters twice as much.
Is a 30-Inch Door Exactly 30 Inches?
Is a 30-inch door actually 30 inches wide?
No. The actual slab width on a nominal 30-inch door is about 29-3/4 inches. This 1/4-inch undersize is consistent across the industry. It exists to allow the door to swing freely within its frame without binding. If you measure an installed door and get 29-3/4 inches, the door is correctly sized.
Are 32-inch doors actually 32 inches?
Same answer: no. About 31-3/4 inches for the slab. The nominal label, the rough opening requirement, and the actual slab dimension are three different numbers. Keep all three straight before you order or frame.
What size is a 30-inch door?
| Nominal Size | Actual Slab Width | Actual Slab Height | Rough Opening Width | Rough Opening Height |
|---|---|---|---|---|
| 24 inches | 23-3/4 in | 79-1/2 in | 26 in | 82 in |
| 28 inches | 27-3/4 in | 79-1/2 in | 30 in | 82 in |
| 30 inches | 29-3/4 in | 79-1/2 in | 32 in | 82 in |
| 32 inches | 31-3/4 in | 79-1/2 in | 34 in | 82 in |
| 34 inches | 33-3/4 in | 79-1/2 in | 36 in | 82 in |
| 36 inches | 35-3/4 in | 79-1/2 in | 38 in | 82 in |
These figures reflect standard residential door conventions. Exterior doors and commercial applications often follow different specs, and some manufacturers vary slightly. Always confirm the actual slab dimension and rough opening requirement with your specific supplier before framing.
How Do Standard Door Sizes Work in Other Units?
If you're working across metric and imperial specs, here's how the most common residential dimensions convert. A 36x80 door (nominal) runs about 908 mm wide by 2,019 mm tall, or roughly 90.8 cm by 201.9 cm. A 32x80 door comes in at about 806 mm wide by 2,019 mm tall. A 30x80 lands near 756 mm wide.
In feet: a standard 80-inch door height is 6 feet 8 inches. A 36-inch wide door is exactly 3 feet nominal. Most residential doors range from 2 feet to 3 feet wide (24 to 36 inches), with heights of 6 feet 8 inches (80 inches) or 7 feet (84 inches) being most common. Exterior door standard sizes in the US tend to start at 36 inches wide and 80 inches tall, with 8-foot-tall doors increasingly common in newer construction.
For reference, standard door sizes in mm for the most common residential widths: 610 mm (24 in), 711 mm (28 in), 762 mm (30 in), 813 mm (32 in), 864 mm (34 in), and 914 mm (36 in). Height in mm for the 80-inch standard is 2,032 mm nominal, 2,019 mm actual slab.
Why Does Door Size Matter More for a Hidden Door Than a Standard Door?
Here's where it gets specific to what we build. A standard door has visible casing, visible hinges, a visible gap between the door and the frame. Nobody's trying to hide any of that. A Murphy Door® hidden door is trying to look like a wall, a bookcase, a pantry, or a mirror until you open it. Every fraction of an inch in the gap shows.
We figured this out the hard way around year three. The problem wasn't weight. It was the reveal. A hidden door needs a 3/16-inch gap on the latch side and top to look right. Bigger than that, and the shadow line gives away the door's location. Smaller, and the door binds when humidity changes cause seasonal wood movement. Our Vaultwood Core construction (a proprietary MDF engineered stronger than standard MDF) with real wood veneer skins holds dimensionally stable across humidity cycles better than a solid-wood slab would. That's exactly why we build that way. We still pre-cut shim stock and include it with every order, along with written torque specs for the hinge bolts, because even a stable door needs a square opening.
I'll tell you what surprised us when we started watching field installations: most out-of-square rough openings aren't way off. They're 1/8 to 3/8 of an inch out of plumb. That's enough to ruin a hidden door reveal and not enough for most contractors to flag as a problem on a standard door. For a hidden door, we ship a frame kit that squares the opening before the door goes in. Not optional.
The Hidden Flush Mount Walnut Wine Rack Door, shown open. The flush mount design requires the door to sit exactly within the wall plane, which means rough opening sizing and shim tolerance have to be right before the door goes in. Note the clean, frameless reveal along the perimeter.
What Murphy Door® Sizes Are Available and What Do They Cost?
We build to a range of widths and heights, both standard and custom. The most common residential widths we ship are 28, 30, 32, 34, 36, and 42 inches. Heights run from standard 80-inch to 84-inch and beyond for taller applications. If your width or height falls outside our standard range, we have a custom width option and a custom height option built into our ordering system.
Here's where prices land across our hidden door catalog:
- Hidden Bookcase Door (flush mount, fully assembled): starting at $1,440.00, view product
- Unassembled Bookcase Hidden Door (DIY, paint grade): $1,000.00, view product
- Paint Grade Flush Mount Bookcase Hidden Door: $1,440.00, view product
- Pantry Murphy Door® (flush mount): $2,800.00, view product
- Wine Rack Hidden Door: $2,280.00, view product
- Mirror Hidden Door (single): $2,320.00, view product
- Mirror Closet French Door: $5,700.00, view product
- Wine Rack French Door: $3,640.00, view product
- Pool Cue French Door: $3,800.00, view product
Every Murphy Door® hidden door ships pre-hung, fully assembled, and QA-inspected before it leaves our Ogden, Utah facility. You're not unboxing a bag of parts. The door arrives tested and ready for your contractor to hang in a square opening. Lead time on most orders is 10 days.
Our hinge and hardware system carries the Patented Ball Bearing Lower Pivot Point, tested to 1,540 lbs, and handles 400 lbs of shelf load on doors up to 36 inches wide. The warranty covers a lifetime on hardware, wood, finishes, and workmanship, with a 1-year warranty on electronics. See our full warranty policy for complete terms.
Want to see finishes and wood options before you commit? Check our woods and finishes page or order samples. Still working out your sizing? Our measurement charts page walks through rough opening requirements for every door we offer.
How Do You Measure for a Hidden Door Correctly?
Measure the rough opening, not the existing door or door frame. Three measurements: width at the top, width at the middle, width at the bottom. Use the smallest of the three. Same process for height: left side, center, right side. Use the smallest. If your smallest width and largest width differ by more than 1/4 inch, the opening isn't square enough to hang a hidden door without framing work first.
Look, here's what we've learned after serving 200,000+ households since 2012: homeowners consistently measure the interior passage (what they can walk through) rather than the structural opening. Those two numbers are different by the thickness of the jamb and stops on each side. For a hidden door order, we need the rough opening, the framed-out hole in the wall before any finish trim or jamb is installed.
If you're not sure which number you have, call us at 888-458-5911 and we'll walk through it. We'd rather spend 10 minutes on the phone confirming your opening than have the wrong-sized door show up at your house. You can also use our guide on choosing a hidden door or book a virtual consultation if you want eyes on the space before you order.
For DIY installs, our DIY hidden door collection includes the Hidden Door Starter Kit and unassembled options with complete instructions. Our how-to support videos cover the installation process step by step. And if you want someone else to handle it, check our installation services for professional install options in select cities.
Start Your Project
Ready to size your hidden door or just need to talk through your rough opening? Call us directly at 888-458-5911 or visit murphydoor.com. We've been at this since 2012, we know which questions to ask, and we won't waste your time.
About Murphy Door®
Murphy Door® is headquartered in Ogden, Utah, and has served 200,000+ households since 2012 from our Utah and Kentucky factories. We're the largest hidden door company in the world and manufacture our hinge and hardware systems in-house, which is why we can back every door with a Lifetime Warranty on Hardware, Wood, Finishes, and Workmanship (with a 1-year warranty on electronics). Every Murphy Door® hidden door is built on Vaultwood Core (a proprietary MDF engineered stronger than standard MDF) with real wood veneer skins in your choice of species, plus solid hardwood face frames and solid-wood components. The Patented Ball Bearing Lower Pivot Point, part of a hinge and hardware system tested to 1,540 lbs, handles 400 lbs of shelf load on doors up to 36 inches wide. Featured in Forbes, Fortune, Fox News, HGTV, and Architectural Digest. Call 888-458-5911 or visit murphydoor.com.
Frequently Asked Questions
Q: What size door do I need for a 32-inch opening?
A: For a 32-inch rough opening, you need a nominal 30-inch door, which has an actual slab width of about 29-3/4 inches. The two-inch difference between rough opening and nominal door size accounts for the jamb on each side plus shimming room. If you're installing a hidden door in that space, confirm the opening is square at top, middle, and bottom before ordering.
Q: What is the actual clear width of a 36-inch door?
A: Clear width runs about 34 inches on a standard 36-inch door once the door stop and hinge side are factored in. The slab itself is about 35-3/4 inches, but the passage narrows when the door is open. If you need a specific clear width for accessibility or code compliance, work backward from that requirement to find the right nominal door size.
Q: Is an 80-inch door actually 80 inches?
A: No. The actual slab height on a nominal 80-inch door is about 79-1/2 inches. The half-inch difference exists to give clearance at the floor. For hidden doors, this matters because your reveal gap at the top and floor clearance at the bottom both need to be calculated using the actual slab height, not the nominal number.
Q: What is a standard door size in cm and mm?
A: The most common US residential door size, 36x80 inches, converts to about 91.4 cm wide by 203.2 cm tall (nominal), or 914 mm by 2,032 mm. Actual slab dimensions convert to roughly 908 mm wide by 2,019 mm tall. For a 30x80 door: about 762 mm wide by 2,032 mm tall nominal, with the actual slab at roughly 756 mm by 2,019 mm.
Q: Do you have to order a 36-by-83-inch door?
A: No. The 83-inch figure usually describes a pre-hung door unit's overall frame height, not the slab. The slab in that unit is typically 80 inches. When ordering any door, confirm whether the dimension quoted is the slab, the frame, or the rough opening requirement. Murphy Door® quotes slab dimensions and provides the required rough opening measurements separately on every product page.
Q: What is the standard door size for exterior doors in feet?
A: Standard exterior door sizes in the US start at 3 feet wide by 6 feet 8 inches tall (36x80 inches). Wider options at 3 feet 6 inches (42 inches) and taller options at 7 or 8 feet are increasingly common in newer construction. Local building codes typically specify minimum egress dimensions for exterior entries, so check your local requirements before ordering or framing.