- Choosing the right bifold doors starts long before you place your order; it begins with accurate measurements. Whether you’re replacing an existing door system or installing bifold doors in a new build, precise measurements ensure a seamless installation, smooth operation, and long-term performance.
This guide explains how to measure for bifold doors correctly, covering standard and custom sizes, rough openings, and practical tips to help you avoid costly mistakes.
Why Accurate Measurements Matter
Bifold doors are designed to fold and stack neatly while providing wide openings, abundant natural light, and a seamless transition between indoor and outdoor spaces. Because multiple door panels operate together, even small measurement errors can affect alignment, weather sealing, and overall performance.
Taking accurate measurements helps you:
- Ensure the doors fit perfectly within the opening
- Prevent installation delays
- Minimize costly modifications
- Improve energy efficiency
- Ensure smooth door operation
- Achieve a clean, professional finish
Whether you’re choosing aluminum bifold doors for a patio, garden, balcony, or commercial opening, measuring correctly is the first step toward a successful installation.
Tools You’ll Need
Before measuring, gather the following tools:
- Tape measure
- Spirit level
- Pencil
- Notepad or phone for recording dimensions
- Step ladder (if required)
- Measuring assistant for larger openings
Always record your measurements in the same unit (millimeters or inches) to avoid confusion.
Measure the Width
The width of your opening should always be measured in three places:
- Top
- Middle
- Bottom
Record all three measurements. If the measurements differ, use the smallest width when ordering your bifold doors. This ensures the door system can be installed correctly without requiring significant alterations to the opening.
Measure the Height
Next, measure the opening height from the finished floor level to the underside of the structural opening.
Take measurements on the:
- Left side
- Centre
- Right side
Again, use the smallest measurement if there is any variation. This helps compensate for floors or lintels that are not perfectly level.
Check That the Opening Is Square
Even if the width and height appear correct, the opening should also be checked for squareness.
Measure diagonally from:
- Top left to bottom right
- Top right to bottom left
The two diagonal measurements should be very close to each other.
If there is a noticeable difference, the opening may require adjustment before installation.
Check Floor Level
A level floor is essential for bifold doors.
Use a spirit level to check whether the floor slopes across the opening.
Uneven floors can affect:
- Door alignment
- Roller performance
- Locking operation
- Weather sealing
If the floor isn’t level, speak with your installer before ordering.
Measure the Structural Opening
Always measure the structural or masonry opening rather than the existing door frame when replacing old doors. Existing frames can hide irregularities or reduce the available opening size. If you’re unsure whether to measure the existing frame or the structural opening, consult your installer before placing your order.
Standard Bifold Door Sizes
Bifold doors are available in a variety of standard sizes suitable for residential and commercial applications.
Common configurations include:
- 60 × 80 inches
- 72 × 80 inches
- 96 × 80 inches
- 108 × 80 inches
- 120 × 80 inches
- 144 × 80 inches
These dimensions are available in multiple panel configurations depending on your design preferences and opening width. If your opening falls outside standard dimensions, custom-made bifold doors can be manufactured to suit your exact requirements.
Measuring for Custom Bifold Doors
Not every project fits standard dimensions. If you’re ordering custom bifold doors, additional measurements may be required, including:
- Overall opening width
- Overall opening height
- Finished floor level
- Frame depth
- Wall construction
- Threshold requirements
- Opening direction
- Number of panels
- Preferred stacking configuration
Providing complete information helps ensure your doors are manufactured accurately.
Replacement vs New Construction
Replacing Existing Doors
When replacing sliding doors, French doors, or older bifold systems:
- Remove interior trim if possible
- Measure the structural opening
- Check for damaged framing
- Verify floor level
- Inspect for moisture damage
Avoid relying solely on the dimensions of the existing doors.
New Construction
For new builds:
- Measure after structural openings are complete
- Confirm finished floor height
- Ensure lintels are installed
- Verify wall dimensions
- Check architectural drawings against actual site measurements
Builders should avoid ordering doors before the opening has been fully prepared.
Common Measurement Mistakes to Avoid
Many installation issues begin with incorrect measurements.
Avoid these common mistakes:
- Measuring only once
- Measuring the existing frame instead of the opening
- Forgetting to account for finished flooring
- Ignoring uneven walls
- Not checking diagonals
- Mixing inches and millimeters
- Guessing measurements
- Ordering before confirming dimensions
Taking a few extra minutes to verify measurements can prevent expensive delays later.
Measurement Checklist
Before ordering your bifold doors, confirm that you have:
- ✔ Measured the width in three places
- ✔ Measured the height in three places
- ✔ Checked the opening is square
- ✔ Confirmed the floor is level
- ✔ Measured the structural opening
- ✔ Decided on the opening direction
- ✔ Selected your preferred panel configuration
- ✔ Confirmed standard or custom sizing
When Should You Call a Professional?
While many homeowners can take preliminary measurements themselves, larger openings and custom installations often benefit from a professional site measure.
A professional installer can:
- Verify structural dimensions
- Identify potential installation challenges
- Recommend the best panel configuration
- Confirm threshold options
- Ensure your order is accurate
This extra step can save time and help avoid costly manufacturing errors.
Frequently Asked Questions
Can I measure bifold doors myself?
Yes. Homeowners can take initial measurements using a tape measure and spirit level. However, professional verification is recommended before ordering custom bifold doors.
What if my opening isn’t perfectly square?
Minor variations are common, but larger discrepancies may require corrective work before installation to ensure smooth door operation.
What are the most common bifold door sizes?
Popular sizes include 60 × 80, 72 × 80, 96 × 80, 108 × 80, 120 × 80, and larger custom configurations, depending on the number of panels.
Can bifold doors be custom-made?
Yes. Custom bifold doors can be manufactured to fit unique openings, making them suitable for renovations, extensions, and architectural projects.
Should I measure before or after flooring is installed?
Always measure after the finished floor level has been established, as flooring thickness can affect the final opening height.
Accurate measurements are the foundation of a successful bifold door installation. By measuring the width, height, diagonals, floor level, and structural opening carefully, you’ll reduce installation issues and ensure your new bifold doors deliver the performance, appearance, and durability you expect.
Whether you’re selecting a standard-size model or investing in custom bifold doors, taking the time to measure correctly will help you achieve a perfect fit and a smooth installation from the very beginning.
