Walk into any home improvement store and you will see stacks of doors labeled “prehung” at nearly twice the price of a basic slab. So what does prehung door mean, and why do contractors reach for these first on almost every remodel? A prehung door is a complete unit: the door itself, hinges already mortised and attached, and a matching jamb assembled around it. You buy a ready-to-install package, not a flat slab that needs drilling, routing, and fitting on site.
The Anatomy of a Prehung Door Unit
Pop open the shrink wrap on a typical prehung and you get four parts working as a system. The slab (the door itself), the jamb (three pieces of wood forming the sides and top of the opening), pre-installed hinges (usually three 3.5 inch hinges on interior doors), and a pre-bored hole for the knob and strike plate.
Exterior prehung units add a sill, a weatherstrip gasket around the jamb, and often a factory-applied threshold sweep. That complete package is the reason a prehung exterior door runs $250 to $600 at big box stores while a plain slab of the same design sits around $80 to $150.
Prehung vs Slab: When Each One Wins
Slab doors are the right call when your existing jamb is square, plumb, and in good shape. You save money, reuse the trim, and skip re-shimming. Expect to spend an afternoon with a chisel, a hinge template, and a 35mm Forstner bit for the knob.
Prehung units win in new construction, additions, or any project where the old frame is rotted, out of square, or getting replaced for style reasons. A framer can set a prehung in 20 to 30 minutes. Installing a slab into an existing frame, by contrast, typically takes a careful DIYer two to three hours per door.
Standard Sizes You Will Actually See
Interior prehung doors come in a narrow range of US standard sizes. Knowing these saves time at the store:
- 24 inches wide by 80 inches tall (closets, small baths)
- 28 inches wide by 80 inches tall (secondary bedrooms, pantries)
- 30 inches wide by 80 inches tall (most interior doors)
- 32 inches wide by 80 inches tall (ADA-friendly, master suites)
- 36 inches wide by 80 inches tall (entry doors, main hallways)
Exterior prehungs add a 36 by 80 single and common 60 by 80 or 72 by 80 double units. Jamb thickness for interior units is usually 4-9/16 inches to match 2×4 walls with half-inch drywall on each side. For 2×6 exterior walls, order a 6-9/16 inch jamb.
Swing Direction: Don’t Order the Wrong One
Every prehung is either left hand or right hand. Stand on the side of the door that swings toward you. If the hinges are on your left and the door swings into the room on the left, it’s a left-hand inswing. Getting this wrong means a restocking fee or a lot of uninstalling and flipping.
For exterior doors, the terminology expands to inswing and outswing. US residential code typically requires main entry doors to swing inward. Secondary doors, screen doors, and doors in tight mudrooms sometimes swing out.
What a Prehung Door Costs in 2026
Budget interior prehungs with a hollow-core flush slab run $70 to $120 at Home Depot or Lowe’s. Six-panel molded units in the same range land between $90 and $160. Solid-core interior doors, which kill sound and feel substantially heavier, climb to $180 to $300.
Exterior prehung steel doors start around $250 for a basic 36 by 80 and climb to $600 or more for insulated fiberglass with decorative glass inserts. Custom sizes, knotty alder, or mahogany units can hit $1,500 to $3,000. Installation labor from a pro runs $150 to $350 per door on a replacement, more if the rough opening needs reframing.
Installing a Prehung: The Short Version
The install is straightforward if your rough opening is sized correctly (typically 2 inches wider and 2-1/2 inches taller than the prehung unit itself). Here is the contractor’s sequence:
- Dry-fit the unit in the rough opening and check the subfloor is level
- Shim the hinge-side jamb first, using cedar shims behind each hinge
- Drive 8d finish nails or 2-1/2 inch trim screws through the jamb into the king stud
- Check plumb in both directions with a 4-foot level, not a torpedo
- Shim and fasten the latch-side jamb with a consistent reveal of 1/8 to 3/16 inch
- Install the top jamb shims, then nail the casing
A common rookie mistake is pulling the plastic retainer clips off the slab before the unit is fully fastened. Those clips hold the reveal while you shim. Leave them on until the last nail.
When to Skip Prehung and Stick With a Slab
Historic homes with plaster walls, custom trim, and out-of-square openings often do better with a slab. Trying to fit a modern prehung into a 1920s opening can mean tearing out plaster, reframing, and losing original casing. A carpenter with a hinge mortise jig and a lock installation kit can hang a slab into the old jamb in a couple of hours without disturbing the historic finishes.
Homeowners on a tight budget replacing a single damaged slab also save real money going with just the slab. A $90 slab plus $30 in hardware beats a $180 prehung you do not need.
Final Take
So circling back to the original question: what does prehung door mean in practical terms? It means you are buying a fully assembled, ready-to-install door package that cuts installation time from hours to minutes. For new builds, full-gut remodels, and exterior replacements, prehung is almost always the smart money. For slab-only swaps in good frames, save the cash and keep your existing jamb.
