Alpha Series Planning Guide

How to measure
for an Alpha Door.

Accurate sizing for Alpha Bookcase and Alpha Mirror doors starts with the opening—not the existing casing. Choose the method that matches your doorway today.

Choose your methodAlpha vs. Standard
!
Never size an Alpha Door from the outside of the existing case molding.

Use either the exposed rough opening or the finished jamb opening. Do not combine the two methods.

Start here

Which opening do you have?

Rough framing is the preferred method. If a conventional door and jamb are still installed, use the finished-opening method instead.

Rough-opening conversion
Rough opening − 2″ = Alpha Door size

A 38″ × 82″ rough opening requires a 36″ × 80″ Alpha Door.

Method 1

Measure the rough opening

Measure to framing at three locations. Width and height are determined by the smallest readings.

Alpha Door rough opening diagram showing width A, height B, and wall depth C
A — WidthMeasure stud to stud at the top, middle, and bottom. Record the smallest measurement.
B — HeightMeasure from the finished floor to the underside of the header at the left, center, and right. Record the smallest measurement.
C — Wall / jamb depthMeasure from one outside finished wall surface to the other, excluding case molding. If the depth varies, record the largest measurement.
Flooring must be included. Measure height from the final finished floor. If flooring is not installed, subtract the planned flooring and underlayment thickness from the measured height.
Watch first

Measuring a rough opening

The assembled jamb needs installation and shimming space. It should not fit tightly against the framing.

Alpha size calculator

Convert rough opening to order size

Enter the smallest width and height measured from the rough framing. Decimal inches are accepted.

This calculator applies the standard 2-inch deduction. Contact Hide-A-Way Doors before ordering if your opening is nonstandard or out of square.

Enter both measurements to calculate your Alpha Door size.
Method 2

Measure an existing finished jamb

Open the existing door. These finished-opening measurements equal the Alpha Door order size—do not subtract two inches.

E — Finished widthMeasure from one jamb face to the opposite jamb face at their furthest points. Do not measure from the stop, hinge, or casing.
D — Finished heightMeasure from the final finished floor to the underside of the top jamb.
Order-size example: A finished jamb opening measuring 36″ × 80″ requires a 36″ × 80″ Alpha Door.
Existing finished opening diagram showing Alpha Door height D and width E
Watch first

Measuring an existing doorway

See which jamb surfaces establish the finished opening and where to place the tape.

Odd-size openings

Adjust the opening—or request a custom size

A small framing adjustment can often create a standard rough opening. Never reduce it below the target size.

38½″ rough opening

Fill the extra ½ inch

Bring it to 38″ for a standard 36″ Alpha Door. Keep the framing solid, square, and plumb.

38¾″ rough opening

Keep the opening centered

Adding the full ¾ inch to one side may affect casing coverage. About ⅜ inch on each side can keep the unit centered.

Need a custom Alpha size? Email sales@hideawaydoors.com or call 888-928-4534 before ordering.
Case molding coverage diagram for hidden doors
Trim planning

Case molding does not determine door size

Hidden-door trim covers the wall differently from conventional casing. Confirm the Alpha Door size from the rough opening or finished jamb first, then consider the surrounding finish.

If you want to try your own trim, write “Please leave trim unattached” in the customer comments. The supplied trim can remain available as a fallback.

Review trim options →
Final verification

Check before ordering

ConfirmWhat to verify
Correct methodEvery measurement comes from either rough framing or finished jamb faces.
Finished floorThe height accounts for flooring and underlayment.
Opening conditionThe framing is square, plumb, solid, and allows installation space.
Order sizeThe 2-inch deduction was used only for a rough opening.
ConfigurationSwing direction, wall clearance, and Alpha step-over are understood.
Alpha vs. StandardSwing directionPass-through clearance

The purchaser, builder, and installer are responsible for verifying field dimensions and site conditions. Consult a qualified carpenter or installer if any measurement is uncertain.

Common questions

Alpha measuring FAQ

Are Alpha Bookcase and Alpha Mirror doors measured the same way?

Yes. Both use the rough-opening or finished-jamb methods explained above.

Do I subtract two inches from a finished jamb opening?

No. The two-inch deduction applies only to rough-opening width and height. Finished jamb dimensions correspond directly to the order size.

What if the opening varies from top to bottom?

Use the smallest width and height. For wall or jamb depth, use the largest measurement.

Can I measure before flooring is installed?

Yes, but the full planned thickness of flooring and underlayment must be deducted from the opening height.

Still unsure?

Verify your Alpha opening with us.

Send measurements and photos before ordering. Our team can help identify whether your opening needs a standard size, a framing adjustment, or a custom Alpha Door.

Contact a hidden door specialist