How to Measure

Measuring for your secret Alpha Bookcase and Mirror Doors made easy.

rough opening chart

Determing Door Size

For accurate door sizing, it's recommended to measure your opening from the wall's framing, commonly referred to as the Rough Opening or "RO." To determine the actual size of your door subtract 2" from the width and the height of your RO measurements.

  1. To measure the width ("A"), start from the wall framing (stud) on one side and measure across to the other side. Measure at least 3 different spots and write down the smallest measurement
  2. To measure the height, from the floor* to the bottom of the header framing ("B") in at least 3 different areas and write down the smallest measurement
  3. To measure the wall or jamb depth measure from the outside of the wall covering (typically 1/2" drywall) to the other side of the wall making sure not to measure with the case molding attached ("C"). if the measurement varies some write down the largest width of the wall and go by that when ordering

*It is of utmost importance to consider the flooring when determining the height of your door. If you measure the height before installing the flooring, the door may not fit properly.

Measuring from an Existing Door

When possible, it is always better to measure your door size from the rough opening, but what do you do if you have an existing door in the opening?

finished opening chart

Measuring from an Existing Door

  1. Open your door
  2. "E" measure across your opening from the surface of the jamb on the right to jamb surface on the other side, this measurement corilates to your door size (width).
  3. Make sure you measure from the furthest point and not from the door stop or the hinge
  4. "D" Measure from the top of your finished floor* to the underside of your finish jamb on the top, this measurement corilates to your door size (height).

*It is of utmost importance to consider the flooring when determining the height of your door. If you measure the height before installing the flooring, the door may not fit properly.

Helpful Hints:

  1. A properly measured door will have a small space of about 1/4" between the outside of the door's jambs and the wall framing (rough opening). A door is not meant to fit snugly in any opening, if your door fits snugly it was either measured incorrectly or your rough opening is out of square; some adjustments to your opening maybe necessary
  2. The door size is determined by subtracting 2" off the width and height of the rough opening, this is typical of a conventional door as well as all of our products

FAQ: What do I do if I have an oddly sized door that you do not have a size for? Example, my rough opening is 38-1/2" what do I order?

Answer: While we can custom build any size that you need, it is less expensive to fill in the opening a bit to make a standard size work. So, if you have a 1/2" thick board you can attach it to one side or the other in your rough opening to bring the RO size down to 38" for a 36" door. Keep in mind that however you fill your RO with, you do not want to go below your target with, in this example that is 38" a fraction larger is fine but do not modify it so that it is less than 38".

Another example, lets say your opening is around 38-3/4" and you want to close the distance by 3/4" Filling a full 3/4 of an inch on one side only might present an issue with the case molding on your door covering your opening properly. In this case, we suggest installing 3/8" material on both sides of your rough opening.

Please feel free to contact us if you need a custom size: or 888-928-4534 (please leave a message if we are unable to answer)


Case Molding Specs per Door Size

The case molding used on hidden doors varies significantly from the trim found on conventional doors. One notable distinction is the extent of wall space covered by our case molding compared to the molding on your current door. Please take into consideration that if your existing wall has wallpaper or was painted up to the edge of your existing door's case molding, our trim might not completely conceal it.

Important: Your door cannot be sized by the current width of your existing door's case molding. Door sizes can only be determined by the RO or Finished Opening measurements.

FAQ: Can I use my trim on your doors?

Answer: It is extremely hard to tell from our perspective. Our doors were designed with our trim in mind. Our doors have been tested and proven to work with the trim that we provide. If you wish to try your trim, in customer comments write, "Please leave trim unattached." Then, if you receive our door and your trim doesn't work, you will be able to fall back on our trim and attach that instead.