What Size Interior Door Do I Need? How to Measure for a Prehung Door
Quick answer: most interior doors in U.S. homes are 80 in. tall and 28 to 32 in. wide, and 30 x 80 in. is the most common size for bedrooms and bathrooms. To pick the right prehung door, measure the rough opening (the framed hole in the wall), not the old door. A 30 x 80 prehung door typically needs a rough opening of about 32 in. wide by 82 to 82 1/2 in. tall. Then check wall thickness for the jamb and note which way the door swings.
Below: how to measure, a size chart by room, and the prehung, slab and core choices.
What Are the Standard Interior Door Sizes?
Interior doors are sold by their slab size, width x height, in inches. Height is almost always 80 in. in homes with 8 ft ceilings. Widths step up in 2 in. increments.
| Door width | Typical use | Notes |
|---|---|---|
| 18 to 24 in. | Linen closets, small reach-in closets, utility spaces | Narrow; not meant for regular foot traffic |
| 28 in. | Smaller bathrooms, closets, older homes | Common in homes built before the 1990s |
| 30 in. | Bedrooms, bathrooms, laundry rooms, pantries | The most common interior door size |
| 32 in. | Bedrooms, main hallways | Easier for moving furniture through |
| 36 in. | Primary suites, accessible doorways, garage entry | Gives the most clear width for wheelchairs and walkers |
Replacing a door? Match the existing size. Framing a new opening? 30 or 32 in. suits most rooms.
How Do I Measure for a Prehung Interior Door?
A prehung door comes already hung on its hinges in a frame (the jamb), so the frame has to fit the opening in the wall. Here's how to measure:
- Remove the casing (trim) on one side if you're replacing an existing prehung door. You need to see the framing, not the trim.
- Measure the rough opening width between the wood studs (the "jack studs") at the top, middle and bottom. Use the smallest number.
- Measure the rough opening height from the subfloor (or finished floor, if it stays) to the underside of the header on the left and right. Use the smallest number.
- Measure wall thickness from the face of the drywall on one side to the face on the other. This sets the jamb width.
- Note the swing: which side the hinges are on and whether the door swings into the room or out toward the hallway.
What rough opening does each door size need?
A simple rule: rough opening = door width + about 2 in. and door height + about 2 to 2 1/2 in. The extra space leaves room to shim the frame plumb and square.
| Door size | Rough opening (approx.) |
|---|---|
| 24 x 80 in. | 26 x 82 to 82 1/2 in. |
| 28 x 80 in. | 30 x 82 to 82 1/2 in. |
| 30 x 80 in. | 32 x 82 to 82 1/2 in. |
| 32 x 80 in. | 34 x 82 to 82 1/2 in. |
| 36 x 80 in. | 38 x 82 to 82 1/2 in. |
If your opening is a little bigger, shims and casing will cover the gap. If it's smaller than the door frame, the opening has to be reframed or you need a narrower door.
What Jamb Width Do I Need?
The jamb is the frame the door hangs in, and its width needs to match the wall thickness. A standard interior wall built with 2x4 studs and 1/2 in. drywall on both sides is about 4 1/2 in. thick, which a 4 5/8 in. jamb fits with a little room to spare.
If your walls are thicker (2x6 framing, plaster walls, or added paneling), you'll need jamb extensions or a wider jamb. Measure before you order, because this is the step most people skip.
Prehung or Slab: Which Should I Buy?
| Prehung door | Slab door | |
|---|---|---|
| What you get | Door already hinged in its jamb | Door panel only |
| Best for | New openings, damaged frames, remodels | Swapping a door into a frame that's still good |
| Install effort | Set, shim and nail the unit | Mortise hinges and drill for the lockset to match the old frame |
| Fit risk | Low if the rough opening is right | Higher; the old frame must be square |
For most homeowners, prehung is the easier route: the hinges are already aligned, so you mainly shim the unit level and plumb. A slab makes sense when the existing frame is in good shape.
Solid Core or Hollow Core?
- Solid core doors are heavier, feel more substantial when you close them, and do a noticeably better job of blocking sound. They're the better pick for bedrooms, bathrooms and home offices.
- Hollow (honeycomb) core doors are lighter and cost less. They're fine for closets and low-traffic spaces.
Which Door Fits Most Bedrooms and Bathrooms?
If your measurements land on a standard 2x4 wall with a rough opening around 32 x 82 in., the 30 in. x 80 in. White 1-Panel Shaker Solid Core Prehung Interior Door is built for exactly that situation. It's the door our customers order most. Here's why it works for so many rooms:
- Solid core MDF, 1 3/8 in. thick, for a quiet, solid close
- Primed white, ready for your paint color
- 4 5/8 in. finger-jointed pine jamb, sized for standard 2x4 walls
- Left-hand or right-hand in-swing, reversible for out-swing, with satin nickel, oil-rubbed bronze or black hinges
- Single bore for a standard knob or lever, assembled to order
The same 1-panel Shaker style comes in 24 in., 28 in., 32 in. and 36 in. widths, so closets, bedrooms and wider openings can all match. You can browse every style, including glass-panel and honeycomb options, in our interior doors collection.
How Do I Tell a Left-Hand From a Right-Hand Door?
Handing describes which side the hinges are on and which way the door swings. The simplest way to avoid a mix-up is to record it from the hallway side:
- Stand in the hallway, facing the doorway.
- Note whether the door should swing away from you into the room (in-swing) or toward you (out-swing).
- Note whether the hinges are on your left or right.
Handing terms aren't used the same way by every manufacturer, so if you're unsure, send us a photo of the opening and a note on the swing and we'll confirm the handing before your door is built.
What About the Door Between the House and the Garage?
The door between an attached garage and the house usually has to meet a fire-rating requirement under local building codes. Don't use a standard bedroom door there. Check your local code, then choose a fire-rated house-to-garage prehung unit. Contact our team with your opening size and swing, and we'll point you to the right door.
Frequently Asked Questions
What is the most common interior door size?
30 x 80 in. is the most common size for bedrooms and bathrooms in U.S. homes. 28 in. and 32 in. widths are also common, all at 80 in. tall.
How much bigger should the rough opening be than the door?
Plan on about 2 in. wider and 2 to 2 1/2 in. taller than the door. For a 30 x 80 prehung door, that's roughly 32 x 82 to 82 1/2 in.
Can I put a 30 in. door in a 32 in. rough opening?
Yes. That's the standard fit. The extra inch on each side leaves room to shim the jamb plumb, and the casing covers the gap.
Is a solid core door worth it for a bedroom?
For most people, yes. Solid core doors block more sound and feel sturdier, which matters most for bedrooms, bathrooms and offices.
Do prehung doors come with the doorknob?
The 1-panel Shaker prehung doors come with hinges installed and a single bore for the knob or lever. The knob itself is a separate purchase, so you can choose the finish.
Can I paint a primed interior door?
Yes. Primed doors are ready for paint. Lightly scuff-sand, wipe off the dust, and apply two coats of a quality interior paint.
Ready to Order Your Doors?
Measure each opening, note the wall thickness and swing, and match it to a size in the chart above. If anything doesn't line up, or you're doing a whole house and want the sizes checked, call us at 215-745-7900 or contact our team. We're happy to review your measurements before you order.