If you are about to order a TWF roller garage door, download the Measuring Guide PDF and use the video below to guide you through each step, so you can measure with confidence.
Measuring is quick, but accuracy matters. The PDF is your full reference, and the video helps you follow along step by step.
For best results, keep the PDF open while you measure. Pause at each step, write your figures down in mm, then double check before you order.
Once you have your measurements, use the Garage Door Builder to select your options.
How to Measure a Garage Door Opening
To measure a garage door opening for a roller door, take the width at the top and bottom, the height from the finished floor to the underside of the lintel, the left and right side returns, and the clearance above the lintel for the top box. Measure in mm, from inside looking out, and use the smallest measurement if it varies.
| Measurement | What to measure | Notes |
|---|---|---|
| 1. Opening width (top) | Brick to brick at the top of the opening | Record in mm |
| 2. Opening width (bottom) | Brick to brick at floor line | Measure the tightest point |
| 3. Opening height | Finished floor to underside of lintel | If floor slopes, measure on the highest side |
| 4. Left return | Opening edge back to wall or obstruction | Inside looking out |
| 5. Right return | Opening edge back to wall or obstruction | Inside looking out |
| 6. Top clearance | Lintel area up to nearest obstruction above | Confirms top box position |
Record each measurement in millimetres (mm), from inside the garage looking out.
Step 1: Measure the opening width at the top (brick to brick)
Measure across the opening at the top, brickwork to brickwork.
Step 2: Measure the opening width at the bottom (brick to brick)
Measure across the opening at the floor line, brickwork to brickwork. If there is a threshold or uneven floor, measure at the tightest point.
Step 3: Measure the height from the floor to the underside of the lintel
Measure from the finished floor to the bottom of the lintel. If the floor slopes, take the measurement on the highest side.
Step 4: Measure the left pillar or side return width (inside)
Measure the clear return from the opening edge back to the inside wall or obstruction. Measure at the tightest point. Remember, left and right is from inside looking out.
Step 5: Measure the right pillar or side return width (inside)
Repeat on the right side. Measure the clear return from the opening edge back to the inside wall or obstruction. Measure at the tightest point.
Step 6: Measure top box clearance above the lintel (inside)
Measure from the top of the opening (lintel area) to the nearest obstruction above (ceiling, beams, pipes, etc). This confirms whether the top box can sit behind the lintel or needs to sit below it.
Tape measure (5m or longer), step ladder (if needed), pencil and paper (or notes app).
Measure to the brickwork, not trims. Check for thresholds and any obstructions near the opening.
Make a note of anything that could affect the fit, for example pipes, lights, sockets, and internal trims.
Make sure you are measuring from the finished floor level (do not measure to loose gravel) and double check your figures. A roller door cannot be made larger once manufactured.
© 2025 – TWF Roller Garage Doors is a trading name of TWF ROLLER GARAGE DOORS LTD | All rights reserved.
TWF ROLLER GARAGE DOORS LTD is an independent retailer and is not authorised by or affiliated with any garage door manufacturer mentioned. Product names, including “Roller Garage Doors,” may be trademarks of their respective owners.
© 2025 – TWF Roller Garage Doors is a trading name of TWF ROLLER GARAGE DOORS LTD | All rights reserved.
TWF ROLLER GARAGE DOORS LTD is an independent retailer and is not authorised by or affiliated with any garage door manufacturer mentioned. Product names, including “Roller Garage Doors,” may be trademarks of their respective owners.
