How to measure a door opening before you order European doors
By the DoorFlux Pro installation team. Updated 2026-11-03.
European doors are made to order and often take weeks or months to arrive, so a wrong size is expensive. Measure the rough opening width in three places and the height on both sides, measure the wall thickness, and decide the swing direction. Then compare your numbers with the door maker's size chart before you pay.
What you need
- A tape measure, a pencil and paper
- A level, to see if the opening is straight
- The finished floor already installed, or its planned thickness
- The door maker's size chart, if you already picked a model
Step by step
Measure the width three times
Measure between the studs (or the old frame) at the top, middle and bottom of the opening. Write down the smallest number. Openings are rarely perfectly straight, and the door has to fit the narrowest point.
Measure the height on both sides
Measure from the header down to the finished floor on the left and on the right. Write down the smaller number. If the two differ by more than about 1/4", the floor is not level, so tell the installer.
Measure the wall thickness
Measure from the face of the drywall on one side to the face on the other side. Include tile or paneling if the wall has it. This number decides which frame you order and whether you need jamb extensions.
Check that the opening is straight
Hold a level against both sides and the top. A tilted or twisted opening can still work, but the installer needs to know before the door is ordered.
Choose the swing direction
Stand outside the room, in the hallway, facing the door. If the hinges are on your left and the door opens into the room, it is a left-hand inswing. Hinges on the right make it right-hand; a door that opens toward you is an outswing. Many European pre-hung doors cannot be reversed later.
Pick the hardware
Decide between concealed 3D hinges (flush, modern look) and visible hinges, and the lock type: passage (no lock), privacy (bathrooms and bedrooms) or keyed. European locks are usually magnetic and pre-cut at the factory in metric sizes, so they must be chosen with the door.
From opening size to door size
Many telescopic European frames need an opening at least 2" wider and 1 1/2" taller than the door slab. Some flush and hidden frames need different gaps, so always check the chart for your model.
| Door slab | Smallest rough opening |
|---|---|
| 28" × 80" | 30" × 81 1/2" |
| 30" × 80" | 32" × 81 1/2" |
| 32" × 80" | 34" × 81 1/2" |
| 36" × 84" | 38" × 85 1/2" |
| 36" × 96" | 38" × 97 1/2" |
Common European door heights sold in the US are 80", 84" and 96". Slabs are usually about 1 5/8" thick.
Wall thickness and jamb extensions
A typical telescopic European frame covers walls from about 4" to 5 3/8" without extra parts. A standard US interior wall with 2×4 studs and 1/2" drywall on both sides is about 4 1/2", which fits. Walls with 2×6 studs, tile, or double drywall are thicker and need jamb extensions in the same finish as the door. Order them with the door.
Pocket doors
A pocket door needs a much wider rough opening: about the door width × 2, plus 2". For a 30" door that is about 62". The wall also has to be free of pipes and wires where the door slides in, and it must not be load-bearing.
What to send the door seller (and us)
- Rough opening width (smallest of three) and height (smaller of two)
- Wall thickness, drywall to drywall
- Swing: inswing or outswing, left or right hand
- Hinge type and lock type for each door
- A straight-on photo of each opening, floor to ceiling
Not sure about your numbers?
We measure every opening for $100, check the floor, walls and level, and send a written measurement report you can give to the door seller. The $100 is credited toward your installation if you book with us.