How to Measure Door Sizes Before Ordering: A Guide to Correctly Measuring Door Frames and Openings
Summary
Learn the correct way to measure door and frame sizes, including width, height, thickness, and swing direction, to minimize ordering mistakes and on-site adjustments.
Key takeaways
- Door measurements should include width and height at at least 2-3 points because frames or walls may not be uniform across all positions.
- When replacing only the door leaf using an existing frame, measure the original leaf and check leaf thickness, hinge positions, and handle locations.
- When ordering a door with a new frame, measure the wall opening, wall thickness, and consider the finished floor level before production.
- Verify the opening direction (left or right hinges) and take site photos to include with the information sent to the manufacturer.
- For custom doors, multiple units, or out-of-square openings, have a technician or manufacturer take on-site measurements to reduce errors.
Measuring door sizes before placing an order is a crucial step. Even a difference of just a few millimeters can prevent installation, cause gaps when closed, or require costly on-site modifications. This is especially important for custom-made doors, wooden doors, or when replacing a door while keeping the existing frame, so you should always take precise measurements beforehand.
Before Measuring: Know What You Are Measuring
Generally, door measuring falls into two main scenarios:
1. Measuring to Replace Only the Door Leaf
In this scenario, the existing frame remains usable, and you only want to replace the door leaf. The measurements required include:
- Width and height of the existing door leaf
- Thickness of the door leaf
- Hinge positions and opening direction
- Knob or handle positions
Recommendation: In this case, you should measure the actual existing door leaf rather than the frame opening, as the original leaf accurately reflects the working dimensions.
2. Measuring to Order Both a New Door Leaf and Frame
For new construction or when removing the entire existing frame, you should measure the wall opening, taking at least:
- Width and height of the opening
- Wall thickness
- Finished floor level and clearance for the frame
- Door opening direction
How to Measure Door Width
Use a tape measure to check the width at 3 points: top, middle, and bottom. Do not measure just a single point, as door frames or walls may not be perfectly aligned throughout.
Example:
- Top: 90.2 cm
- Middle: 90.0 cm
- Bottom: 89.8 cm
In this case, you should report all three values to the manufacturer or use the appropriate value recommended by a technician. Do not hastily assume it is a 90 cm door without actual measurement.
How to Measure Door Height
Similarly, measure at least 2–3 points: left, middle, and right, measuring from the finished floor level to the top of the opening or frame.
If the house flooring is not yet finished, you must account for the future floor level—such as tiles, SPC, wood, or leveling mortar—because the height of the floor after material installation may change.
Do Not Forget to Measure Wall Thickness
This point is often overlooked but is very important if ordering a new frame. Wall thickness affects the frame size, especially for brick-and-mortar walls, drywall, or walls with decorative tiles. You should measure at multiple points and report the actual thickness after surface finishing work.
How to Check If a Door Opening is Square
Even if the width and height are correct, a slanted door opening can make installation difficult. A basic check is to measure the diagonals:
- Measure from top-left corner → bottom-right corner
- Measure from top-right corner → bottom-left corner
If both values are close, the door opening is likely square. If they differ significantly, a technician should inspect the site before production.
You Must Also Specify the Door Opening Direction
In addition to dimensions, clearly specify the opening direction:
- Inswing or outswing
- Hinges on the left or right
Easy Check: Stand on the side where you pull the door toward yourself and see which side the hinges are on. However, taking on-site photos or drawing a layout plan will best minimize errors.
What Additional Measurements Are Needed If Reusing an Existing Frame?
When replacing only the door leaf on an existing frame, additionally measure:
- Size and thickness of the original leaf
- Number and size of the hinges
- Distance from the top edge to each hinge
- Distance from the floor to the handle position, and the borehole for the knob/Mortise lock
- Condition of the existing frame (if swollen, rotted, warped, or termite-damaged, replace the frame)
Should You Measure Yourself or Hire a Technician?
For standard general doors, you can take basic measurements yourself. However, for custom doors, special-size wooden doors, slanted wall openings, old houses, or large-quantity orders, it is recommended that a technician or manufacturer take actual on-site measurements to prevent errors.
Checklist Before Submitting Dimensions to the Manufacturer
- Leaf width, height, and thickness
- Wall thickness
- Using an existing frame or ordering a new frame
- Opening direction (inswing/outswing) and hinge position (left/right)
- Handle/knob position
- Door material type and actual site photos
Frequently Asked Questions (FAQ)
Can I measure the door directly from the frame opening?
Yes, in some cases. But if you are replacing only the existing leaf, you should also measure from the original door leaf to accurately account for opening-closing clearances and perimeter gaps.
What are standard door sizes?
Door sizes vary according to application types, such as bedrooms, bathrooms, or entryways. However, you should never order based on standard sizes alone; always measure the actual site first.
Can minor measurement errors be fixed?
This depends on the door type and the extent of the discrepancy. Some cases allow edge trimming, but certain materials or structures are unsuitable for modification, making accurate measurement from the start essential.
Conclusion
Measuring doors before ordering requires considering more than just width and height. You must also check thickness, swing direction, hinge positions, frame condition, and finished floor levels. If you want to order custom wooden doors or are unsure about dimensions, you can send site photos and basic measurements to Feel Wood for review and evaluation before manufacturing.
Frequently asked questions
What are standard door sizes?
Current primary door sizes include 70x200cm, 80x200cm, 90x200cm, and 100x200cm, but you should never order based solely on standard sizes and should always measure the actual site first.
What needs to be measured before ordering a door?
You should measure the width, height, and thickness of the leaf or wall, check the opening direction, hinge positions, and existing frame condition. For custom doors, actual site photos should also be sent to the manufacturer.
Should a door be measured from the original leaf or the frame?
If replacing only the leaf while keeping the existing frame, measure from the original door leaf along with the frame opening. If replacing both leaf and frame, measure the wall opening and wall thickness.
Why must width and height be measured at multiple points?
Because door frames or walls may be slanted or uneven throughout. Measuring multiple points helps reveal discrepancies and reduces the risk of ordering the wrong size.
Can I measure the door if the house flooring is not yet finished?
Preliminary measurements can be taken, but manufacturing based solely on those dimensions is not recommended. Finished floor levels can vary; in some cases, excessive clearance is left under the door, while in others, the actual floor is higher than expected, causing the door to drag and fail to open or close. Therefore, wait for the finished floor level to be established before taking final measurements for production.
Should custom doors be measured by yourself or a technician?
You can take basic measurements yourself, but for custom doors, special sizes, multiple units, or out-of-square openings, it is recommended that a technician or manufacturer take on-site measurements before actual production.
Can minor measurement errors be fixed?
This depends on the door type and the extent of the discrepancy. Some cases allow edge trimming, but certain materials or structures are unsuitable for modification, making accurate measurement from the start essential.