How to measure for a new door.

The number-one reason doors get returned is a measuring mistake. Ten minutes with a tape measure before you order saves weeks of headaches.

Measuring a door sounds trivial until you realize there are several measurements that matter, and the one printed on your old door is often not the one you order by. Here is how to get it right.

Slab size vs rough opening

There are two different measurements people confuse:

• Slab size — the door panel itself, e.g. 30" x 80" (interior) or 36" x 80" (exterior).
• Rough opening — the framed hole in the wall, which is larger than the door to leave room for the frame, shims, and squaring. A pre-hung door is ordered to fit the rough opening.

If you are replacing a slab in an existing frame, you measure the slab. If you are replacing the whole unit (recommended for exterior doors), you measure the rough opening after the old unit is removed.

Measuring a replacement slab

1. Width: measure the door panel edge to edge at the top, middle, and bottom. Use the largest number.
2. Height: measure top to bottom on both sides.
3. Thickness: common interior is 1-3/8"; exterior is typically 1-3/4". Measure the edge.

Measuring a rough opening

1. Width: measure between the framing studs at top, middle, and bottom; use the smallest number.
2. Height: measure from the subfloor to the header.
3. Wall (jamb) depth: measure the wall thickness so the frame depth matches — older homes vary, which trips up many orders.

Figure out the handing (swing direction)

Handing is where most returns come from. Stand facing the door from the side it swings toward you (the side where hinges are visible):

• Hinges on the left, knob on the right = left-hand door.
• Hinges on the right, knob on the left = right-hand door.
• For exterior doors, also note inswing vs outswing.

When in doubt, photograph the opening from inside and outside and let your specialist confirm the handing on the order.

Common sizes to sanity-check against

• Interior single doors: 24", 28", 30", and 32" wide x 80" tall are most common; 30" x 80" is a typical default.
• Exterior entries: 36" x 80" is the workhorse; 96" tall is common in modern homes.
• Double and pivot doors: 48", 60", 64", 72"+ wide.

These are starting points. We custom-size doors to your exact opening, so the measurement always wins over the chart.

When to call a pro

Measure yourself for a quick budget, but have a specialist confirm before ordering any exterior, oversized, or pivot door — those are expensive to re-order. We coordinate rough-opening dimensions as part of every quote. Browse interior and exterior doors, or contact us to confirm sizing.

Frequently asked questions

What is the difference between slab size and rough opening?

The slab is the door panel itself (for example 30 by 80 inches). The rough opening is the framed hole in the wall, which is intentionally larger to fit the frame, shims, and squaring. Pre-hung doors are ordered to the rough opening; slab-only replacements are ordered to the slab size.

How do I know if I need a left-hand or right-hand door?

Stand on the side the door swings toward you, where you can see the hinges. If the hinges are on the left, it is a left-hand door; if on the right, it is right-hand. For exterior doors, also note whether it swings in or out. When unsure, photograph both sides and let your specialist confirm.

What are the standard door sizes?

Interior single doors are commonly 24, 28, 30, or 32 inches wide by 80 inches tall, with 30 by 80 a frequent default. Standard exterior entries are commonly 36 by 80 inches, with 96-inch heights popular in modern homes. Double and pivot doors run wider. Your actual opening can differ, so measure before ordering.

Should I measure myself or have someone do it?

Measuring yourself is fine for a rough budget. For any exterior, oversized, or pivot door, have a specialist confirm the measurements before ordering, since those are costly to re-order. We coordinate rough-opening dimensions as part of every quote.