How to Measure Wall Opening Size Before Ordering Custom Entry Doors

Purchasing custom entry doors for residential or construction projects starts with accurate wall‑opening measurements. Wrong dimension data is one of the top reasons for delayed shipments, returned goods and extra project costs. Whether you are a building contractor, hardware wholesaler or property developer, you must follow standard measuring rules before submitting door specifications to your door supplier.

Take measurements at three different horizontal points across the wall hole: top, middle and bottom. Always record the minimum value among these three readings as your actual opening width. Walls are rarely perfectly straight; never use the maximum number.

Measure height at three vertical positions inside the opening: left side, center and right side. Select the smallest measured height for your order specification. Uneven concrete floors or ceiling slabs often create height gaps.

Check wall thickness on upper, middle and lower spots of the opening. Again pick the minimum thickness value. Wall thickness decides the door frame profile you can use. Different wall types — normal wall, T‑style wall, double flat wall require matched frame structures.

Door swing direction is easily overlooked. You need to confirm whether the door swings inward toward indoor space or outward to outdoors. Three common wall conditions for inside‑opening doors:

1. Normal wall
2. "T" style wall
3. Double flat wall

Attention: Do NOT order door exactly equal to raw wall opening dimensions. We need proper installation gaps.

• Leave 5‑8 mm gap on both width sides
• Leave 5‑10 mm gap on height These gaps are reserved for installation adjustment, foam filling and leveling.

Example: If your measured wall opening min size: W900mm × H2100mm, Your suggested door leaf dimension will be smaller than opening, reserve installation tolerance.