Standard Exterior Door Sizes & Rough Opening Chart (Prehung vs Slab) — Measuring Checklist

Replacing an exterior door? The fastest way to avoid delays is to confirm two numbers: the door size and the rough opening (RO).

This guide includes standard exterior door sizes, a practical RO chart for prehung units, and a copy/paste measuring checklist for a fast quote.

1) Key terms (to avoid measurement mistakes)

• Door size (slab size): the door panel size (e.g., 36" x 80")

• Prehung unit: door + frame/jambs + hinges (often threshold + weatherstripping)

• Rough opening (RO): framing opening (stud-to-stud width, subfloor-to-header height)

• Jamb depth: wall thickness the frame must match

Most problems happen when people quote the old door slab size instead of the rough opening.

2) Standard exterior door sizes (most common)

Popular single exterior door sizes (W x H):

• 30" x 80" (762 x 2032 mm)

• 32" x 80" (813 x 2032 mm)

• 36" x 80" (914 x 2032 mm) — most common in US/CA

• 36" x 84" (914 x 2134 mm)

• 36" x 96" (914 x 2438 mm)

Popular double door widths (total W x H):

• 60" x 80" (1524 x 2032 mm)

• 72" x 80" (1829 x 2032 mm)

3) Prehung vs slab: which should you choose?

Prehung is recommended for most exterior projects because it installs faster and seals better (frame alignment + weatherstripping).
Choose slab only if you are reusing an existing frame and the hinge/lock prep matches.

We supply prehung and slab, in standard sizes and custom sizes.

4) Rough opening rule of thumb (for many standard prehung doors)

• RO width ≈ door width + 2" (51 mm)

• RO height ≈ door height + 2" to 2-1/2" (51–64 mm)

Note: The exact RO depends on the frame/jamb profile and threshold system. For custom units, always confirm with the supplier.

5) Rough opening chart (typical for prehung exterior doors)

Single door — typical RO:

• Door 30" x 80" → RO 32" x 82"–82.5"

• Door 32" x 80" → RO 34" x 82"–82.5"

• Door 36" x 80" → RO 38" x 82"–82.5"

• Door 36" x 84" → RO 38" x 86"–86.5"

• Door 36" x 96" → RO 38" x 98"–98.5"

Double door — typical RO:

• Door 60" x 80" → RO 62" x 82"–82.5"

• Door 72" x 80" → RO 74" x 82"–82.5"

(If you prefer, use the editor’s “Insert Table” and fill the same values.)

6) How to measure your rough opening

Measure each dimension 3 times and use the smallest value.

• RO width: stud-to-stud at top / middle / bottom

• RO height: subfloor (or finished floor) to header at left / center / right

• Wall thickness / jamb depth: measure finished wall thickness so the jamb depth matches

7) Common mistakes (that cause delays)

• Measuring the old door slab instead of the rough opening

• Not accounting for finished flooring height (threshold conflicts)

• Not confirming handing (LH/RH) and swing (inswing/outswing)

• Ignoring jamb depth (wall thickness mismatch)

8) Copy/paste checklist for a fast quote (RFQ)

Send us the info below and we’ll confirm the best size (standard or custom) and quote for prehung or slab:

1. Project market: US / CA / AU / UK / Middle East

2. Door type: single entry / double entry / other

3. Prehung or slab:

4. Swing: LH/RH + inswing/outswing

5. Rough opening (W x H):

6. Wall thickness / jamb depth:

7. Floor condition: subfloor or finished floor (material & thickness if known)

8. Material: cast aluminum / steel / wood

9. Glass & hardware options:

10. Quantity & timeline:

FAQ

Q: What is the most common front door size in the U.S.?
A: 36" x 80" is the most common.

Q: What RO is typical for a 36" x 80" prehung door?
A: Often around 38" x 82"–82.5", but confirm based on the frame/threshold system.

Q: Do you offer standard and custom sizes?
A: Yes. We supply both standard sizes and custom sizes for US/CA/AU/UK/ME projects.