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How to measure a front door

Learn how to measure your front door accurately — no matter if you have a single front door, double front door, or another variation.

A man measures a rough opening inside a home with green wood siding.

Whether you’re looking to order a new front door or just get a more accurate quote when shopping, measuring is an essential step. It’s not hard to measure a front door, but it might not be intuitive if you haven’t done it before. Not to worry, we’ll explain what you need to know.

What to measure

To measure a door accurately, you need to measure the frame, rough opening, jamb thickness, and panel.

The frame is the outer structure that your door panel fits into when you close your door.
The rough opening is the space in the wall where your door is installed.
The jamb depth (or frame depth) is the thickness of your wall.
The panel is the part of your door that swings open (or operates). When you think of a door, the panel is likely what you imagine.

Hint: It can be helpful to review the parts of a front door before measuring.

In the photo on the left, a contractor is preparing a rough opening in advance of installing a new door. In the photo on the right, a contractor makes an adjustment to the hinge connecting the panel and frame.

The rough opening is the hole in the wall where your door is installed. In the photo on the left, a contractor is preparing a rough opening in advance of installing a new door. A panel is the part of the door that opens (or operates), and the frame is what the panel fits into. In the photo on the right, a contractor makes an adjustment to the hinge connecting the panel and frame.

How to measure a single door

Picture of blueprints with a tape measure, level, nails and a tool belt laying on top

1. Gather your supplies.

You’ll need a tape measure, pencil, and paper.

An illustration of a front door showing where to measure panel width.

2. Measure the panel’s width

From the top, center, and bottom. Write down all three measurements. If they vary, use the shortest dimension.

An illustration of a front door showing where to measure the panel height.

3. Measure the panel’s height

From the left, center, and right. Write down all three measurements. If they vary, use the shortest dimension.

An illustration of an open front door showing where to measure jamb depth (or wall depth) when measuring your front door.

4. Measure the jamb depth (frame depth)

To do this, open the door and measure along the frame from the back of the exterior trim to the back of the interior trim.

An illustration of a front door showing how to measure height and width.

5. Measure the frame

To do this, go outside and check if your door has brickmould (or exterior trim) overlapping the door frame.

If there’s no overlap, measure width from the outer edge of the frame on one side to the outer edge of the frame on the other side. Measure at the top, middle, and bottom of the door and use the smallest dimension. Next, measure the height from the top edge of the frame down to the bottom of the sill on the left, middle, and right. Use the smallest dimension.

If you have brickmould that appears to overlap the frame, you’ll need to take this measurement from the inside. This will require removing your interior trim (or casing) so you can see the frame. Once you remove the casing, take the same width and height measurements described above.

An illustration showing a framed-out wall with rough opening for door and lines indicating where to measure the rough opening for height and width when trying to determine the correct door size.

6. Measure the rough opening

The most accurate way to do this is by removing the casing surrounding your door. You would then measure the width between the studs (or sides of the rough opening). Again, we recommend taking three measurements from the top, center, and bottom of the opening and using the smallest dimension. Then, measure from the header (beam at the top of the rough opening) down to sub-floor (floor beneath the door’s sill and finished floor). Again, take three measurements from left, center, and right and use the smallest dimension.

If you’re ready to order a new door but don’t want to take on measuring yourself, it might be time to contact an Andersen Certified Contractor.

Why is it necessary to take all these various measurements?

If you’re replacing a front door, the easiest solution is to get a door that’s the exact same size as your current door. This is why you measure the frame size of your current door and use those dimensions when ordering your new door. However, it’s also important to measure the rough opening. This is because doors don't always fit their rough openings well. Understanding if the fit is too tight or too roomy gives you the opportunity to decide if you want to change your door size to better fit the space.

Measuring the panel is a way to uncover two things: One, is your door a non-standard size? If so, you’ll want to match that size. Two, have you measured correctly? If the current door’s panel and new door’s panel vary greatly in size, you probably want to measure again.

Similarly, you want to measure jamb depth to make sure your wall isn’t extra thick. Although there are three industry standard wall thicknesses — 4 9/16”, 5 9/16”, and 6 9/16” — your wall could fall outside of what’s standard for a variety of reasons. If your wall’s a non-standard thickness, you want to make sure your new door is the same.

We sell non-standard size doors in addition to standard size doors, and you can specify the size down to 1/8 of an inch.

Types of front doors

While single front doors are the most common, they’re not the only type of front door. Still, whether you have a double door, a door with a window next to it (called a sidelight), or a door with a window above it (called a transom), you’ll want to measure frame, rough opening, jamb depth, and panel. Read on for more details about measuring these various types of front doors.

How to measure a front door with a sidelight, transom, or both

If your front door has a sidelight or transom, you should still follow the steps described above and take all measurements described. Sidelights and transoms are a part of the rough opening, so taking that measurement will allow you to order the right size windows and door. With the rough opening dimensions, you would be able to make sure the new configuration of door and sidelight and transom fits the space. For example, you might order a standard panel and adjust the transom and/or sidelight to fill the rest of the space.

A natural wood front door with five horizontal windows and a sidelight next to it completes the clean, modern look of a white-painted brick home.

Measuring the rough opening allows you to determine what size the new configuration of door and sidelights and/or transoms should be in order to fit the space.

How to measure a double door

Follow the instructions above for measuring your door frame, rough opening, jamb depth, and panel. Then work with your contractor, builder, or dealer to order the right size doors to fit the space.

A traditional shingle-style colonial home with a deep front porch and a double front door with transom above it.

The home above has double front doors and a transom above. To measure a door like this, you would measure the frame, rough opening, jamb depth, and panels.

What to keep in mind when replacing a front door

While measuring a front door for replacement will be the same as what’s described above, there is one particular decision you’ll also need to make: Do you want to order a replacement door with or without a flange? An installation flange is a component that extends from the frame and attaches to the rough opening in order to anchor the door and help facilitate drainage. If it’s possible to remove your exterior trim, or if you’d like to update the exterior trim along with the door, then you would order a new front door with a flange, and it would be installed just like in a new construction scenario. If you don’t want to replace the exterior trim or it’s not possible to do so — sometimes the façade is too tight to the door — then you would order a flangeless front door, and it would be installed a little differently.

Remember, Andersen Certified Contractors have specialized window and door installation knowledge and can help with front door project — find one in your area.

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