Hidden Door Planning Guide

Measure once.
Order the right door.

Start by selecting your hidden door type. Single and Double Doors share this guide; Alpha and BiFold Doors have separate measuring requirements.

Choose your door typeSingle & Double instructions
!
Do not measure to the outside of your existing case molding.

Measure the rough framed opening or the finished jamb opening only. Existing casing dimensions will produce the wrong door size.

Measuring guide directory

What type of hidden door are you measuring for?

Select the door type before taking measurements. Alpha and BiFold Doors include design requirements that are not covered by the standard guide below.

This page

Single Doors

Measure an exposed rough opening or an existing finished jamb using the standard method below.

Measure a Single Door → This page

Double Doors

Double Doors use the same rough-opening and finished-jamb measuring method as Single Doors.

Measure a Double Door → Separate guide

Alpha Doors

Review Alpha-specific sizing and the permanent 6½-inch step-over built into the door frame.

Open the Alpha guide → Separate guide

BiFold Doors

BiFold units mount to the wall surface and require finished-opening and overhead-clearance measurements.

Open the BiFold guide →
Single & Double Doors

What does your doorway look like today?

Choose one path and use it from beginning to end—do not mix measurements from the two methods.

The rough-opening rule
Rough opening − 2″ = hidden door size

Example: a 38″ × 82″ rough opening orders as a 36″ × 80″ hidden door.

Method 1

Measure an exposed rough opening

Measure framing—not drywall edges or trim. Take each measurement carefully and record it before calculating the door size.

Diagram showing rough opening width A, height B, and wall depth C
A — Rough-opening widthMeasure stud to stud at the top, middle, and bottom. Record the smallest measurement.
B — Rough-opening 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 the outside finished wall surface to the other outside finished wall surface. Exclude case molding. If the depth varies, record the largest measurement.
Finished flooring changes the opening height. Always measure from the final floor surface. If flooring has not been installed, subtract the full thickness of the planned flooring and underlayment before ordering.
Watch the process

How to measure a rough opening

The opening must leave installation and shimming space around the jamb; the assembled unit should not fit tightly against the framing.

Quick calculator

Convert your rough opening to door size

Enter the smallest rough-opening width and height you recorded. Decimal inches are accepted.

This calculator applies the standard 2-inch deduction. Confirm nonstandard openings with Hide-A-Way Doors before ordering.

Enter both measurements to calculate your door size.
Method 2

Measure an existing finished jamb

Open the conventional door before measuring. These jamb-opening dimensions correspond directly to the hidden door width and height—do not subtract 2 inches again.

E — Finished opening widthMeasure from the face of one jamb to the face of the opposite jamb at their furthest points. Do not measure to the door stop, hinge, or casing.
D — Finished opening heightMeasure from the finished floor to the underside of the top jamb.
Your result is the order size. If the finished jamb opening is 36″ × 80″, select a 36″ × 80″ hidden door.
Diagram showing finished jamb opening height D and width E
Watch the process

Measuring an existing door

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

Nonstandard openings

What if the opening is an odd size?

Small framing adjustments can often create a standard opening. Never reduce the opening below the target rough-opening size.

Example: 38½″ opening

Fill the extra ½ inch

Bring the opening to 38″ for a standard 36″ door. Keep the framing square, plumb, and solid.

Example: 38¾″ opening

Consider casing coverage

Adding the full ¾ inch on one side may affect trim coverage. Splitting the adjustment—about ⅜ inch per side—can keep the door centered.

Need a custom size? Contact the team at sales@hideawaydoors.com or 888-928-4534 before placing the order.
Diagram explaining case molding coverage around a hidden door
Plan the finish

Case molding is not an opening measurement

Hidden-door trim coverage differs from conventional casing. Size the door from the rough opening or finished jamb opening, then plan the trim around that confirmed size.

If you intend to use your own casing, write “Please leave trim unattached” in the customer comments on your order. The factory-provided trim can remain available as a fallback.

Review hidden door trim options →
Final check

Before you order

ConfirmWhat to verify
OpeningMeasurements are from framing or jamb faces—not outside casing.
FloorHeight begins at the final finished floor surface.
ConsistencyYou used one measurement method from start to finish.
FitFraming is square, plumb, structurally sound, and allows installation space.
ConfigurationSwing direction and surrounding wall clearance are confirmed.
Swing direction guidePass-through clearanceThings to know before ordering

The purchaser, builder, and installer are responsible for verifying field dimensions and site conditions. If any measurement is uncertain, consult a qualified carpenter or installer before ordering.

Common questions

Measuring FAQ

Should I subtract 2 inches from every measurement?

No. Subtract 2 inches only when converting rough-opening width and height to door size. Finished jamb opening measurements correspond directly to door size.

Which measurement should I use if the opening varies?

Use the smallest width and height so the unit can fit through the entire opening. For wall/jamb depth, use the largest measurement.

Can I measure before the flooring is installed?

Yes, but you must account for the full planned flooring and underlayment thickness. Ordering from the subfloor height without that deduction can make the door too tall.

Does this guide apply to BiFold hidden doors?

No. BiFold doors have separate requirements. Use the BiFold measuring guide.

Still unsure?

Let’s verify it before you order.

Send the Hide-A-Way Doors team your opening measurements and photos. We can help identify the right next step for a standard or custom opening.

Contact a hidden door specialist