Dealer buying guide
How to Measure a Bifold Door Opening: Step-by-Step Guide
Getting the measurements right is the difference between a smooth install and a costly reorder. Here is the exact method our engineers ask every customer to follow.
By X Star Industry Co., Ltd Technical Team · Published August 3, 2026
Why accurate measurements matter
When you order a bifold door from a factory in China, every panel is manufactured to your exact specifications. There is no cutting it to fit on-site. A measurement error of even half an inch means the door arrives too big — or too small — and your project stops.
The good news? Measuring correctly is simple if you follow a consistent method. Here is how our engineers ask every customer to measure.
Before you start: tools and prep
- A tape measure at least 25 feet long
- A pencil and paper (or your phone's notes app)
- Ideally a second person to hold the tape
- Make sure the opening is clean and unobstructed
Step 1: Measure the width in three places
Measure across the opening at the top, middle, and bottom. Write down all three numbers.
Step 2: Measure the height in three places
Measure from floor to head at the left, center, and right. Again, note all three.
Step 3: Check for square
Measure both diagonals (corner to corner). If they differ by more than 1/4 inch, your opening is out of square — the wall, not the door, is off. A professional installer will need to correct this before installation, or the door can be designed with adjusting tolerances.
Step 4: Note the wall construction
- Frame material: timber, steel, or block
- Opening depth (wall thickness) at the jamb
- Any tiling or flooring not yet installed — it will raise the finished floor level
Step 5: Record everything and send it
Send us:
- All three width measurements
- All three height measurements
- Diagonal difference
- Wall construction details
- Photos of the opening
Common mistakes that cost money
- Measuring only one spot — openings are rarely perfectly square
- Measuring to the edge of drywall instead of the stud — the door will sit proud
- Forgetting planned floor tiles — the door won't fit once the floor is raised
- Assuming the opening is square without checking diagonals
What happens after you send your measurements
Our team reviews your numbers, confirms the configuration, and produces a detailed CAD drawing of your door before anything goes into production. You approve the drawing, we build. That is how we keep order errors below 1%.
Have a project in mind?
Send us your opening measurements — width, height, wall construction, and photos — and we will come back with a configuration proposal within 24 hours.