When planning a commercial door installation, many people ask: what is standard door size, and can it be used in a non-standard opening? The answer is yes, and in most cases, it’s the smarter approach. At CDF Distributors, we strongly recommend using standard size doors instead of ordering fully custom products whenever possible. With the right adjustments, standard doors can fit a wide variety of openings while delivering significant cost and scheduling benefits.
What Is a Standard Door Size?
In commercial construction, door sizes are standardized to simplify manufacturing, installation, and replacement. Both metal and wood doors typically come in a 1-3/4” thickness and are produced in a range of common dimensions.
Standard Commercial Door Width Options
- 2'0" (24")
- 2'6" (30")
- 2'8" (32")
- 3'0" (36") - the most popular standard commercial door width
- 3'4" (40")
- 3'6" (42")
- 3'8" (44")
- 4'0" (48")
Average Commercial Door Height Options
- 6'8" (80") - great for older buildings
- 7'0" (84") - the most popular standard door height
- 8'0" (96")
The most commonly used combinations are 3068 (3’0” x 6’8”), 3070 (3’0” x 7’0”), and 3080 (3’0” x 8’0”). These sizes are widely available, making them ideal for most projects.
A Note on Nominal Height and Width
When reviewing door specifications, you’ll often hear the term nominal width and nominal height. These terms can be confusing at first, but they play a critical role in selecting and installing the right door.
What Is a Nominal Door Size?
Nominal size refers to the labeled or “in-name-only” dimensions of a door—such as 3’0” x 7’0” (3070). However, the actual physical size of the door slab is slightly smaller than these dimensions.
For example:
- a 3070 nominal door (3'0" x 7'0")
- Actual door size is typically about 35-7/8" x 83-7/8"
This slight reduction allows space for:
- The door frame
- Hinges and hardware
- Proper clearances for smooth operation
In other words, the nominal size represents the rough opening the door is designed to fit into to, not the exact slab measurement.
Why Nominal Size Is Important
Understanding nominal dimensions helps avoid costly mistakes during planning and installation. Here’s why it matters:
Accurate Opening Preparation
Your opening likely already exists, and you’re looking for a door that best fits those dimensions. Understanding nominal sizing ensures that you account for the frame, anchors, and necessary hardware clearances, helping the complete door and frame system fit properly within the opening.
Compatibility with Standard Frames
Commercial frames are built to match nominal door sizes. Using the correct nominal width and height ensures that the door, frame, and hardware all align properly.
Better Fit and Performance
When you specify a door as “3070” or “3068,” suppliers instantly understand the correct proportions. This standardization reduces confusion and minimizes ordering mistakes.
Better Fit and Performance
Doors need precise clearances to open, close, and latch correctly. Nominal sizing ensures those clearances are built into the system from the start, preventing issues like binding, sagging, or uneven gaps.
Simplifies Field Adjustments
When you're adapting a custom opening to fit a standard door, working with nominal sizes makes it easier to determine how much to add or remove from the opening. It provides a consistent reference point for installers.
Key Takeaway
Nominal door size isn’t just a label—it’s a standardized system that ensures everything fits and functions as intended. By understanding the difference between nominal and actual dimensions, you can confidently select the right door and avoid installation surprises.
When combined with the flexibility of adjusting openings, nominal sizing is what makes using standard doors in custom openings both practical and efficient.
Why Use Standard Sizes Instead of Custom Doors?
Although custom doors can be manufactured to exact specifications, they often introduce unnecessary complexity. Here’s why CDF Distributors recommends sticking with standard options:
Lower Costs
Custom doors require special production, increasing material and labor costs. Standard doors are mass-produced, making them more affordable.
Faster Lead Times
Standard sizes are readily available or in stock, helping you avoid long manufacturing delays.
Easier Installation
A standard commercial door width and height is designed to work with common frames and hardware, reducing installation issues.
Future Flexibility
If a door needs to be replaced later, sourcing a standard door is much easier and quicker than recreating a custom size.
How to Use Standard Doors in Custom Openings
Even if your opening doesn’t match a standard door height or width exactly, there are proven ways to make it work. The key is adjusting the opening rather than reinventing the door.
Step-by-Step Process
1. Measure and Compare
Start by measuring the opening:
- Width
- Height
- Wall Thickness
Then select the closest standard door size and determine whether the opening is too large or too small.
2. Adjust the Opening
If the opening is too large:
- Recommended: Add framing or infill materials
- Wood studs: add lumber or framing members
- Metal studs: install additional studs or tack
- Masonry: use block, grout, or steel infill
- Acceptable: Minor build-backs using blocking or shims
3. Account for Wall Type
- Wood studs: easiest to modify
- Metal studs: may require reinforcement
- Masonry: most precise and least forgiving
4. Install the Frame
- Set the frame plumb, level, and square
- Anchor it based on wall type
- Use shims only for final adjustments (not major corrections)
5. Finish with Trim
- Cover small gaps around the frame
- Use trim for aesthetics, not structural fixes
6. Final Check
- Ensure smooth door operation
- Confirm consistent gaps
- Verify clean, aligned trim
By following this process, you can successfully use a standard commercial door width and average commercial door height even in a custom opening.
Why Choose CDF Distributors?
At CDF Distributors, we make commercial door projects easier, more efficient, and more cost-effective.
Expert Door Guidance
Our experienced team understands how to match standard door sizes to real-world openings. We’ll help you determine the best fit without overpaying for custom solutions.
Reliable Product Availability
We stock the most common configurations, including popular widths like 3’0” commercial door width and standard door height options.
Personalized Support
Most importantly, our door experts will guide you through the entire process—from selecting the right size to adjusting your opening—so you can confidently use a standard door in a custom space.
Final Thoughts
Understanding what is standard door size and how to apply it can dramatically improve your project’s efficiency. With common options for standard commercial door width and average commercial door height, most openings can be adapted without the need for expensive custom doors.
If you’re planning your next project, trust CDF Doors to help you simplify the process. We’ll show you how to make standard doors work, saving you time, money, and hassle along the way.
