How To Measure A Door The Right Way, The First Time

Measuring a door size sounds pretty basic, right? Just break out a tape measure and check the height and width of your old door. Yes and no. When it comes to measuring doors, there is actually a bit more to it than taking the length and the width of the door frame.

What measurements you need to take will depend on whether you are replacing just the door or if you are also replacing the frame and hinges. Are you dealing with an existing door space, or are you in the process of constructing? Will you need to measure the depth of the door? Is it going to be a single door or a double door?

In this guide, we’ll walk you through how to measure a front door or measure for a new one with confidence. You’ll learn how to measure from the bottom, check the height of the door frame, calculate the door width and height, and even how to measure the jamb depth—so your measurement is from the door and not just the interior trim.

No more guessing. No more returns. Just simply measure the right way from the interior edge of the door to the exterior edge, and you’ll know exactly what type of door for replacement you need. Let’s start by measuring the width—one side of the door jamb at a time—and make sure your new door is a perfect fit, right from the first try.

 

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Learn How to Measure Doors Correctly and Get It Right from the First Try

Ready to upgrade your space with the dream door you’ve been eyeing? Whether you’re shopping for a prehung front door, replacing an old one, or just figuring out if a pre-hung door unit will fit, getting the measurements right is key. The good news? It’s easier than you think. You just need to know where to measure—from the side jamb from the interior to the bottom of the threshold, and everything in between.

First, find the answers to these questions:

• What to measure when you want to replace solely the door
• How to measure the rough opening when you want to replace everything
• Standard door sizes and what they mean for front doors and interior doors
• When to call the pros and why such a decision can be incredibly beneficial

So, to correctly measure your door and frame, take a look at the following suggestions!

Interior Door Slab Door Measurements

If your frame and hinges are in good condition and you want to keep them, you can replace just the door (known as a door slab) itself.

To measure for an interior door replacement:

1. Measure horizontally across the door in 3 locations: top, middle, and bottom. Record the smallest measurement as the door width.
2. Measure the height of the door vertically in 3 locations: left side, center, and right side. Record the smallest measurement as the door height.
3. Measure the thickness of the door. (A standard thickness for an interior door is 1-3/4”.)
4. Measure the location of all 3 hinges. To obtain these measurements, measure down from the top of the door to the top of each hinge.
5. Measure the width and height of each hinge.
6. Measure the distance from the top of the door to the center of the bore (hole for the handle). For the most accurate measurement, remove the door handle and deadbolt prior to measuring.
7. Measure the distance from the center of the bore (doorknob hole) to the closest door edge.

Additional reading: You might also want to check out What Does Door Installation Cost?

Standard Interior Door Size: Pre-hung System/Net Frame

If the door frame is damaged or you want to replace it for aesthetic reasons, you will want to measure the rough opening dimensions as well. Once you’re done, you can pick a completely new front door or a door system that’s better aligned with your lifestyle needs.

To prepare to take measurements, first, use a pry bar and putty knife to gently remove the trim from around the opening. Use the putty knife to remove any insulation from between the edge of the rough opening and the door slab. This will allow for more accurate measurements.

1. As you would with a simple door slab measurement, measure horizontally across the door slab itself. It’s important to measure 3 locations: top, middle, and bottom. Record the smallest measurement as the door slab width.
2. Also, as with a simple door slab measurement, measure the vertical height of the door slab itself. Measure in 3 locations: left side, center, and right side. Record the smallest measurement as the door height.
3. Take 3 horizontal measurements of the rough opening (top, middle, and bottom). Record the smallest measurement as the rough opening width.
4. Take 3 vertical measurements of the rough opening (left side, center, right side). Record the smallest measurement as the rough opening height.
5. Measure the thickness of the door jamb. Record this measurement as the jamb width.

Additional reading: Thinking about a front door replacement? Take a look at How to Pick the Right Front Door Replacement for Your Home.

Now That You Know How to Measure a Door Size, What Type of Door Should You Buy?

The type of door you install will depend on whether you are replacing a front entry door, a patio door, an interior or exterior door, what material you want, if you want a fiberglass door, and some other details that resonate with your preferences.

A few of the main factors to consider, whether you’re buying a new or a replacement door include:

1. What is the primary purpose of the door?
2. What is your budget?
3. What type of material do you prefer?
4. What style or design fits better?

You also have the choice of various door styles. Once you measure the door and you determine the aesthetics that make the most sense, you can pick one of the following options:

• Metal Doors: Famous because of their sleek and polished nature, more secure. They look good with a variety of colors, but especially against cool tones.
• Flush Doors: They have a plain design with no textures, but can be decorated. A flush door is usually the cheapest one. It lets other features shine in your home.
• French Doors: Usually come in a pair, have glass panels, and are very decorative. Fit in with stunning hardwood floors, patios, and elegant dining rooms.
• Carved Wood Doors: Elegant. More expensive, but worth it.
• Barn Doors: A barn door looks like how you would expect a barn door to look. Adds a vintage look. Rolls across a bar like a sliding door.

Additional reading: This Guide to Choosing the Perfect Exterior Glass Door will give you essential information on one of the most popular options with homeowners.

Expert Door Measurements and Installation, Regardless of Door Design

No matter what kind of door you have in mind—modern, traditional, rustic, or totally custom—Chicago Window Guys has you covered. Our expert team knows that every door has its own personality, and we’re here to make sure it fits just right.

With years of experience and a passion for precision, we specialize in professional door installation that gets it right the first time—regardless of the door design. Whether you’re upgrading your front entry or replacing interior doors, you can count on us to handle every detail with care. Ready to get started? Let’s make that dream door a reality. Get a free quote today!

Post Update: The article was updated on April 24th, 2025, and originally published on December 24th, 2018. It has been completely revamped and updated for accuracy and comprehensiveness.