How to Measure a Door Size?

Before you start shopping for a new door or set of doors, you may want to measure your door to get a rough estimate of your door size. The most accurate way to measure for a replacement door is with the interior – beginning with taking three measurements inside the frame of the door at the top, middle and at the bottom.

Measure a Door Size

It is critical to measure your existing doors before replacing them, as you do not want to end up with an incompatible door.Unfortunately, the majority of people believe that only the height, width, and thickness of the door must be measured in order to get the correct door measurements.

It can't be too far off the mark! If you want to replace a door in your home, you'll need more than just the height and width to ensure a perfect fit! To ensure that the measurements are taken on the spot, follow the steps outlined in this paper.


Imperial or Metrics?

Imperial or Metrics

Let's begin with the big question: should you measure in imperial (meters) or metric (inches) units? We recommend measuring in inches rather than millimeters for the most accurate results. As a result, your installer will be able to ensure a perfect fit for your replacement door.


Door Slab vs Prehung Door Unit

Jamb Frame with Hinges

In the door industry, a door is a complete door unit consisting of a door hung from a complete jamb frame with hinges. Inside doors have side and top jambs but no door sill or threshold.

Exterior doors have a four-sided threshold frame and many of them have exterior finishes such as the brick mold, which is a thick wood molding. If it fits your opening and the style of your house, you can use the brick mold or replace it with other shapes.

Alternatively, you can buy a replacement door that does not have jambs or hinges. This is referred to as a door slab. But don't get bogged down in the jargon: A slab door is a door that stands alone; a slab door or slab-style door has basic, flat sides without any panels or decorative features.

Interior and exterior door measurements are comparable, though prehung exterior doors with trim normally require some additional measurement to make damn sure that the trim fits through the opening for the exterior siding.


Door Terminologies

door Rough Opening

Let's take a look at some of the door vocabulary that's out there to help you understand what's being said.

  • Door Swing Direction

The direction in which the door is meant to swing. Either a door can swing to the right or to the left. You will know where your door is going to go, if you know which directions the door is going to swing.

You'll also know where your door knob is supposed to go . To get a clearer picture, see where the hooks are located and whether the door is swinging to the right or to the left. For instance, if the hinges are on the right, you have a right-hand door.

  • Rough Opening

A rough opening is a structural opening in the wall for a door. It is the aperture formed by the side wall studs, the header at the top, and the floor or sill at the bottom.

  • Jamb

The jamb is the wood framework that surrounds the doorway. It, however, does not include the door trim/casing. As a result, a door jamb is simply the framework within which the door is installed.

  • Sweep/ Weather Stripping

Look at the bottom of the door for a rubber/metal plate that has been adhered to it. This is referred to as sweep or weather stripping. The rubber or metal plate can also be affixed to the door edge to assist prevent air leaks and debris from entering via an opening that would otherwise allow such foibles to enter.

  • Trim/Moulding/Casing

The trim or casing conceals the joint between the jamb and the surface material. As such, it is primarily decorative and should never be included in a door replacement measurement.

Typically, the door frame is half to three-quarters of an inch smaller than the rough opening and roughly two inches shorter. This enables you to fit the framework into the opening and secure it before attaching it to the raw opening frame. On the locations where the nails or tensioners are driven, there are tapered shims; the shims are meant to keep the frame plumb and level.

The frame is tiny and has a lot of dramatic openings in it. When the door is completed, ornamental trim is applied to fill the gaps around the frame and the bridge between the frame and the finished wall. This trim, known as casing, must be removed to measure for a prehung door but can be left in place if only the door slab is being replaced.


5 Steps To Measure A Door For Replacement

To measure the door, all you need is a tape measure; once you have that, simply follow these 5 simple steps:

 Step 1: Measuring the Door Width

Measuring the Door Width

From left to right, run the tape measure well over the width of the door, excluding the surrounding frame and any other components. If you have a frame but no door, take your measurements from the inside of the frame, where the door would be.

Step 2: Measure the Height

Measure the Height

Place the tape measure at the top corner of the door and run it down to the bottom corner of the door to calculate the height while the door is still closed. Remember to take measurements of the slab itself, not the frame or sill. To acquire an accurate height measurement, measure in several places of the door and choose the longest dimension.

Step 3: Measure the Thickness

It is not enough to measure the door's height and breadth; you must also determine the thickness of the door. You should also acquire a measurement of the door frame (jamb), which is where the door rests when closed within the frame.

Step 4: Take the Door Frame Measurement

Take the Door Frame Measurement

Measuring a door's frame is comparable to measuring the door itself. To measure the height, run the tape measure along the inside of the door frame from top to bottom, then take three width measurements: across the top, middle, and bottom parts.

Step 5: Take Several Measurements

Several Measure a Door Size

A door may warp or wear down with time, resulting in it no longer being a perfect rectangle. It's a good idea to take height and width measurements in a few different places, especially when measuring wooden doors:

Width: Towards the top, the center, and the bottom.

Height: On the left, in the center, and on the right.

After that, you'll have a total of six measures. Take the biggest measurement for height and breadth and use it to inform your contractor of the size of door you want.

You're ready to take your information and start shopping for a new door now that you have your door measurements. If you bring these measurements to a showroom, you will be able to get a rough estimate for the door replacement. You can still have professional measurements done, which can provide you insight into more serious alterations you might make to fit different types of doors.


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