Steel French Door Sizes: The Complete Measuring & Buying Guide

Ordering a steel French door is exciting, until you look at the size chart. Suddenly you see numbers like 36x80, 60x96, or 72x80, and no one warned you that "French doors" are actually a whole family of different sizes. Ordering the wrong one will either result in you having to return the product or have the frame rebuilt - neither of which is fun. 

The good news is, this sizing system makes a lot of sense once you know what you're looking at. Below is everything you need to know: standard single and double steel French door sizes, how to properly measure your door opening, and those little things that often confuse people.

What the Numbers Actually Mean

Each steel French door is measured in inches as width x height, and this refers to the door itself - not the opening in your wall. A 36x80 door is 36 inches wide and 80 inches tall. Pretty simple.

Steel French doors come in two configurations:

Single Door — A single panel with glass, used as a simple entryway or side and back doors.

Double Door — Two identical panels that join in the middle to create a wider, more attractive entryway.

Both types of doors are available in a few specific widths and two common heights. Most suppliers, including USA Builders Depot, stock a variety of glass styles and finishes, so if you want something custom-looking, it’s easy to estimate the size.

Standard Single Steel French Door Sizes

Determining the size of a single door is easy, as you only have to think about one panel.

 

36x80 single steel French doors are the most common size in American homes. They fit into most existing frames without causing structural damage, making them a safe option for direct replacement. The 36x96 size is more suitable for new construction or renovations where you want a taller entryway — especially in all-glass or multi-panel designs.

Standard Double Steel French Door Sizes

Many people are confused about double doors because the listed size is the combined width of the two panels, not the single width of any one panel.

A 60x80 double steel door is two 30-inch panels placed side by side. A 72x96 door uses two 36-inch panels and gives you a full six-foot entryway with extra height. 

Doors up to 60x120 are available for larger entryways or commercial projects — typically found in the main entrance of a luxury home or boutique store. The same logic applies to sliding patio doors: The listed size is for the entire unit, not half of it.

How to Measure Before You Order

Before ordering any size steel French door, grab a tape measure and take these measurements:

1. Width — Measure the top, middle, and bottom of the opening. Use the smallest number. Older frames are almost never perfectly straight.

2. Height — Measure from the floor to the top of both sides of the frame. Again, use the smallest number.

3. Wall Depth — Check the depth of the jamb, especially on pre-hung units, to ensure the frame sits flush with your wall.

4. Opening Direction — Will it open to the left or right, inward or outward. Make sure this is correct before ordering.

5. Squareness Test — Measure at an angle from one corner to the other on both sides.

If the difference between these two numbers is more than a quarter of an inch, your opening is not square and needs to be corrected before installation. 

If you are replacing an older door, measuring the existing slab can be a good alternative test. Steel French door sizes are determined based on standard slab sizes, so if the old door is a whole number like 36x80, you're probably dealing with a standard rough opening.

Door Size vs. Rough Opening

This is where most people make mistakes. The size listed on the product page — for example, 36x80 — is the door unit. The rough opening is the hole in the wall that is framed, and it needs to be slightly larger to allow for shims and leveling.

A general rule of thumb is: The rough opening should be about 2 inches wider and 2 to 2.5 inches taller than the door size.

A 36x80 pre-hung steel French door typically requires a rough opening of about 38x82.5 inches. Talk to your supplier before framing anything — insulated steel frames vary slightly by manufacturer.

Why Steel Behaves Differently Than Wood or Fiberglass

Steel French doors are made with a steel shell inside a foam or composite core. This means there are a few important things to know:

It doesn’t change shape with the seasons. Wood swells and contracts with changes in humidity. Steel holds its shape year-round. It will stay in the shape you ordered.

There’s no way to adjust it right away. A wood frame can be adjusted with a little force. Steel can’t. It’s even more important to determine the exact size of a steel French door in advance.

Double doors tend to be heavier. For any door that’s 72 inches wide or wider, make sure the frame, jamb, and hinges can handle the weight before installation day.

Picking the Right Size for Your Situation

Looking to replace an old door? First, measure your current entryway. Standard sizes for steel French doors—36x80 for a single door and 60x80 or 72x80 for a double door—are standard sizes for most American homes without compromising the structure.

Building a new home or completely renovating? Look for 96-inch-high options. These tall sizes work especially well with multi-light glass patterns and give the entryway a more customized and finished look.

Is the side entrance or service door narrow? A 32x80 single door keeps everything compact, while also maintaining the security and weatherproofing features that are the main reasons to buy steel.

Want to really make your entryway stand out? A wide double door with five or more glass panels turns the front of your home into an architectural moment—especially when a covered porch protects the glass from direct weather.

Frequently Asked Questions

What size steel French door is best for most homes? For one door, 36x80 is the ideal size. For two doors, 60x80 and 72x80 sizes work best. 96-inch height versions are becoming more common in new construction. 

Can I have a custom-sized steel French door made? Yes. In addition to standard widths, suppliers like USA Builders Depot make custom-sized doors for openings that don't fit in common configurations. 

How large should the initial opening be to install the door? Typically, it should be about 2 inches wider than the door unit and 2 to 2.5 inches taller. Always check with your specific manufacturer before framing. 

Can I install a 36x96 door in an 80-inch opening? No. This type of height difference means that the entire opening, including the header, will need to be reframed. It's almost always easier to order a door that matches what you have.

Get the Steel French Door Size Right, the First Time

Once you know the difference between slab size and rough opening, and you've taken careful measurements, steel French door sizes aren't complicated. The choice between single and double comes down to your opening width and the look you're after.

USA Builders Depot carries steel French doors in all the standard sizes above — from 32x80 singles to wide double configurations — along with multiple glass patterns and finish options. If your opening is non-standard, custom sizing is available so you don't have to force the wrong door into an unconventional space. 

Browse the full steel door collection to compare options side by side, or contact the team for help matching the right door to your exact opening.