The Ultimate Guide to Standard Door Sizes

Are you renovating your home? Want new doors for your space? Looking to change the door style and refresh your office? Cannot decide between slab or prehung doors? It doesn't matter which of these questions is your active concern because all of them lead to the same point – the door size. It is the one thing you need to know if you want to replace your doors successfully.

Precise door measurements are crucial for their installation – whether it's a slab or prehung door. A tape measure will be your best friend here. 

Fortunately, your door measurements won't be a random set of numbers because the door industry has come up with several door heights, widths, and thicknesses that are optimal for every home. As a result, your door measurements are certain to fall into one of many established dimensions.

Let us now focus on standard door sizes.

Standard Door Sizes

Generally speaking, manufacturers design modern doors to be of the same height. It is a door's width and thickness where the difference lies.

The width is important as it determines the door opening size. This is the space we go through when passing from one room to another. A door that is too narrow or too wide is unfunctional and ruins the aesthetic of the two rooms it connects. The door width has another crucial aspect as it configures the size of the door jamb, which is the part that connects a door to a wall.

However, there are various building codes and acts (IRC, IBC, ADA) that determine the minimum door height and width. They enable you to easily find a replacement for your door in case of damage or stylistic change. This is because building codes and acts have standardized door sizes.

Standard door measurement takes into consideration only a door slab without its hardware. When measuring, you don't include hinges, handles, jambs, frames, and door openings.

With that said, what are standard door sizes for interior and exterior doors in the US market?

What Are Standard Interior Door Sizes?

Interior doors refer to doors that part and connect two rooms or a room and a hallway. This category includes bedroom doors, pocket doors, and barn doors, among many others.

Standard interior door sizes follow the International Residential Code (IRC). However, building codes vary from state to state. As such, a door must fulfill certain requirements in terms of its width, height, and thickness. One such norm dictates that the minimum thickness of standard interior doors is 1 3/8 inches. You can't install a smaller door than the code allows, but you are allowed to install a larger one.

In addition, besides the prescribed criteria there are also non-standard door sizes. This is why it's always good practice to take the doors' measurements when replacing them.

Standard Interior Door Width

These are standard residential door sizes in terms of width for the interior:

• Closet doors do not need to follow the criteria set by the IRC. Some older closet doors are as narrow as 18 inches, but in modern homes they are 30 inches in width.
• The standard interior door width is 28 to 32 inches. Other sizes include 24 and 36 inches (the latter size is the optimal width to accommodate a person with disabilities).
• The standard bifold door sizes you can find on the US market vary from 24 to 36 inches. However, the number of door panels may dictate different dimensions of said panels.
• The width range of 36 to 42 inches are the standard barn door sizes available in retail, which can also vary in thickness.

Standard Interior Door Height

While there is a standard door height commonly used, the demand and circumstances influence the height to range from 80 inches up to 10 feet. Here's an overview of the general door height:

• The standard interior door size is 80 inches, which is the minimum allowed height prescribed by the IRC.
• The standard bifold door size is also 80 inches. Yet, different manufacturers may offer alternative sizes depending on your home's type.
• To go big is what it means when you opt for the standard barn door size that spans from 80 to 96 inches.
• The modern closet door size is standardized at 96 inches. It is often featured in newer homes in the US.

What Are Standard Entry Door Sizes?

Exterior doors are the doors that serve as an entrance or exit into a building. This category includes entry doors, back doors, garage entry doors, fire or security doors, etc.

The IRC also sets the minimal requirements for standard exterior doors as well. Like in previous cases, the states differ in building codes, so be mindful of them. The thickness of a standard entry door is 1 3/4 inches.

Moreover, next to the standard front door sizes, you can also find non-standard exterior door sizes at various door stores.

Standard Exterior Door Width

Here is an outline of standard residential door sizes in terms of width for the exterior:

• The standard width of double exterior doors: 30 - 32 inches.
• The standard front door size in terms of width that is also the most popular choice: 36 inches.
• Often promoted exterior door width in newer homes: 42 inches.
• The common width of exterior pivot doors: 48+ inches.

Standard Exterior Door Height

This is a list of door heights you might see when inspecting the market:

• The standard exterior door size in the US: 80 inches.
• The exterior door height that is featured in older homes: 84 inches.
• Newer homes typically showcase this height for their exterior doors: 96 inches.
• Extravagant homes often display an exterior door height of: 109+ inches.

Commercial Door Sizes

Commercial doors are generally larger and heavier in comparison to residential ones. Depending on their function, they frequently feature different hardware, like panic bars. Standard commercial door sizes are 80 inches in height, with various widths:

• 36 inches for standard commercial exterior doors.
• 28 - 32 inches for standard commercial interior doors.

Commercial door sizes conform to the International Building Code (IBC) and the Americans with Disabilities Act (ADA). These two set the minimum and maximum dimensions of doors to optimize the passageway in case of an emergency.

The IBC sets the minimum door width of commercial buildings at 32 inches and the maximum at 48 inches. Medical institutions feature a minimal width of 41.5 inches. The IBC selects 80 inches as the minimum height of commercial doors.

Following the ADA rules, the width of commercial doors should range from 32 inches up to 48 inches in width, while the commercial door height cannot be under 80 inches in height. The ADA standards also prescribe guidelines for door surfaces, handles, locks, thresholds, closing speeds, etc.

Different Standard Door Sizes

In the table below, you can find a summary of the previously mentioned doors and their standard sizes.

How to Measure a Door?

The first step to replacing your doors is to take measurements. But, how do you measure a door? Is there a special trick to it? If there is, what is the proper way to measure a door?

Measure a Door Slab

When replacing a door slab, you'll want first to measure it without taking the frame, hinges, and other hardware into account. As such, you can measure the door slab while it's still hanging, since the jamb and the frame will remain the same.

To have the most accurate measurements of your door slab, follow the steps below:

1. Measure the door's height near the left edge, at the center, and near the right edge.
2. Measure the door's width at its top, middle, and bottom – do this on the inside and the outside of the door.
3. Measure the door's thickness – the distance between the interior and exterior side of the door.

In addition, pay close attention to the door swing, which can be inswing or outswing for the left or right hand. It is good information to have to optimize your door's functionality.

In case you opt to change the entire door system, the dimensions of the door slab are less important. The jamb measurements will dictate the size of the interior doors, while the frame and sill dimensions will determine the size of exterior doors.

Standard Door Frame Sizes

A door frame is a structure that supports a door. It has three segments:

• Two vertical or side jambs
• One horizontal or head jamb

The standard door frame size is 80 inches in height and 36 inches in width. In some cases, the width will vary depending on the door type (interior or exterior, sliding or French, etc.).

The standard door opening sizes are around 2 inches larger in width and height: 38x82 inches. However, another practice is to add 2 1/2 inches to the door's height instead of just 2 inches.

What is the Standard Door Jamb Width?

A jamb is a part of a door's wooden or metal frame. Its size is crucial for your door. Too large ones can be trimmed, but if a jamb is too small it won't allow your door to function properly.

When taking the measurements for your door, it is good practice to measure the height, weight, and thickness of the door jamb, along with measuring the frame.

The standard door jamb sizes depend on the frame's dimensions and the drywall thickness. Here are some standard door jamb widths:

• 4 9/16 - 5 1/2 inches
• 6 9/16 inches

Do Doors Have to Be the Exact Size?

If you are replacing a door slab, then the answer is yes. Your new door slab should be the same size as your current one, if it's to fit the existing door frame. The same size doesn't require a new door frame. However, if you go for a smaller door, you will need a shortened frame, and with a larger door you will need a bigger frame.

The size of the door is proportional to the door frame. This means that the frame has to be of a certain size to be able to fit the door and handle its weight during its operation. Different door sizes have different thicknesses, which have a direct impact on which frames can support such doors.

Where to Buy Standard Doors?

It is important to carefully select your doors before purchasing them, since they can impact the safety, functionality, and aesthetics of your home.

If you want to refresh your home and elevate your style, feel free to browse through our selection of standard interior doors and exterior doors.

The Discount Hardware offers a variety of sizes and styles to enhance your home and comfort with affordable prices and a two-year limited warranty.