Accurate door measurements are the foundation of a perfect installation.
Even the most durable and stylish door will not perform well if its size doesn’t fit the opening.
Mistakes in measuring can lead to extra costs, alignment issues, and poor insulation.
In this guide, Estdoor experts explain how to measure a doorway precisely, so your new door fits perfectly the first time.
Why Accurate Measurements Matter
Measuring “by eye” or checking only the width often results in:
- a door that doesn’t fit into the frame or leaves gaps;
- drafts, uneven closing, and poor thermal insulation;
- locks that jam or require excessive force.
To avoid this, you need to take three key measurements, width, height, and wall thickness.
What You’ll Need
Before you start, prepare:
- a tape measure (at least 3 m long);
- a level or laser level to check alignment;
- a pencil and notepad for notes;
- a helper, if the door opening is large.
Step-by-Step Measurement Guide
1. Measure the Width
Measure the distance between the walls in three points, top, middle, and bottom.
Take the smallest value as your reference to ensure a snug fit for the frame.
2. Measure the Height
Again, take three measurements, left, centre, and right.
Measure from the finished floor to the top of the opening.
If flooring will be added, account for its thickness.
3. Measure the Wall Thickness (Depth)
This is essential for choosing the right frame and trims.
Take several readings along the wall, many openings are uneven.
If the difference exceeds 10 mm, note it for the installer.
4. Check Geometry and Alignment
Use a level to make sure the opening is vertical and even.
If the deviation exceeds 5-10 mm, the wall may need adjustment before installation.
Common Measurement Mistakes
Avoid these typical errors:
- measuring only one point instead of three;
- ignoring plaster or decorative finish thickness;
- measuring over an old, deformed frame;
- forgetting to leave a 10-20 mm installation gap around the frame.
Recommended Doorway Sizes
| Door Size (mm) | Recommended Opening (mm) | Note |
|---|---|---|
| 800×2000 | 870×2070 | Interior doors |
| 900×2100 | 970×2170 | Standard entrance doors |
| 1000×2100 | 1070×2170 | Reinforced or double doors |
Leave a 10-20 mm gap between the frame and wall on each side for foam and adjustment.
When to Call a Professional
Sometimes it’s better to trust the experts:
- if the wall is uneven or has irregular geometry;
- if you plan to install an insulated steel door;
- if you need a custom-sized or designer model.
When you order an Estdoor door, you can also request a professional measurement service.
Our specialist will visit your site, take all dimensions, and recommend the ideal model.
Estdoor Recommendations
- Confirm whether your measurements are taken before or after wall finishing.
- For insulated metal doors, include the door leaf and frame thickness.
- Always use professional mounting foam and anchor bolts during installation.
In Summary
Precise measurement is the first step to a long-lasting, secure door.
If you’re unsure, let Estdoor handle it, we’ll save you time and guarantee accuracy.
Request a free consultation and get expert advice on the right dimensions and door type for your home.
