Getting the wrong roller door size is an expensive mistake. Order a door that's too small and it won't fit the opening. Too large and you can waste money on material you don't need. The issus is that roller doors need accurate measurements, not just the opening width and height but also the space around it for tracks, drums, and the motor. This will enable you to determine the overall door size which is how roller doors in Australia are specified. Door size is opening height with nothing added and opening width PLUS the overlap into the tracks - generally 50mm or 100mm extra overall.
You can measure for a new roller door yourself with a tape measure, notepad, and about 20 minutes. The process involves measuring your garage opening at multiple points, checking clearances above and beside the opening, and confirming you have enough ceiling depth for the door mechanism. No guesswork needed.
This guide walks you through each measurement step by step. You'll learn what standard roller door sizes exist in Australia, how to measure your opening correctly, what clearances you need for installation, and how to finalise your size based on your specific garage. By the end, you'll have accurate measurements ready for your roller door order or quote.
What you need before you start
You don't need specialist equipment to measure for a new roller door. A standard tape measure (at least 5 metres long), a notepad or phone for recording measurements, and a helper to hold the tape are enough. Most garages require you to measure at height, so a stepladder or stable chair helps you reach the top of the opening safely.
Essential tools and materials
Before you begin how to measure for a new roller door, gather these items so you don't waste time searching mid-measurement. Having everything ready means you'll capture accurate figures the first time instead of making multiple trips up and down a ladder.
- Tape measure (5-metre minimum, steel preferred for rigidity)
- Notepad and pen or phone for recording every measurement
- Stepladder or stable platform to reach the lintel safely
- Helper to hold the tape steady for wide openings
- Spirit level (optional but useful for checking if the opening is square)
- Torch if your garage has poor lighting
Take three measurements at different points for both width and height. Garage openings are rarely perfectly square.
Clear any stored items away from the door opening before you start. You need full access to the frame and surrounding walls.
Step 1. Understand standard roller door sizes
Before you begin to measure for a new roller door, you need to know what sizes are commonly available in Australia. While there are not standard sizes, there are common sizes and doors are priced in ranges. All custom sizes between 2551mm and 2800mm are the 2800mm price etc. Common Roller door sizes exist for single and double garages, and knowing these dimensions helps you confirm whether your opening falls within the typical range or requires a more custom-made solution although all doors are made to order. Most Australian manufacturers produce roller doors in set height and width increments, which affects pricing and lead times.
Single garage roller doors
A standard single garage roller door in Australia measures approximately 2100mm in height and 2400mm in width. These dimensions suit most single-car garages built to Australian building standards. However, manufacturers can produce doors from 1250mm to 3100mm in height and 1850mm to 3150mm in width for single openings.
If your opening measures close to standard sizes, you'll typically save on costs and installation time.
Check whether your vehicle fits these dimensions comfortably. A 4WD or SUV with roof racks or aerials may need a taller door, while wider vehicles demand greater clearance on each side.
Double garage roller doors
Standard double garage roller doors measure approximately 2100mm in height and 4800mm in width across Australia. Manufacturers typically offer double doors from 2100mm to 3100mm in height and 4200mm to 5400mm in width depending on the opening and structural support available.
Larger openings above 5000mm wide sometimes require reinforced drums and heavier motors to operate smoothly. You'll pay more for wider doors because they use additional materials and stronger components to handle the extra weight and wind load.
Step 2. Measure the garage opening
You'll measure both the width and height at multiple points because older garage openings are rarely perfectly square. Walls settle, lintels sag, and concrete slabs shift over time, creating slight variations that affect your final door size. Taking three measurements for each dimension ensures you capture the true opening size instead of assuming it's uniform.
Measure the opening width
Start by measuring the horizontal distance between the inner faces of the left and right door jambs. You need three separate width measurements taken at different heights to account for any taper or bow in the walls. Measure at the top of the opening (just below the lintel), at the middle (roughly halfway down), and at the bottom (at floor level).
Record each measurement in millimetres and write them down immediately. For example, you might record Top: 2405mm, Middle: 2400mm, Bottom: 2398mm. The largest measurement determines your minimum door width because the door must cover the widest point. In this example, you'd use 2405mm as your opening width.
Use the largest width measurement to ensure your roller door fits without gaps or the edge of the tracks being exposed
Check the bottom edge carefully for any weather strips, raised thresholds, or floor nibs that reduce the actual width. These often sit flush with the jamb and can steal 10-20mm from each side.
Measure the opening height
Measure the vertical distance from the finished floor to the underside of the lintel (the horizontal beam above the door). This measurement is less critical, but you still need to order the best height door for your situation. If you have sufficient space above the opening (Head Room) a slightly higher door will give the best finish and protect from leaves, dust and even birds getting in through the gap at the top of a roller door.
Floors are rarely perfectly level. If your garage floor slopes towards the driveway, measure from the highest point of the floor surface. Any existing door strip or seal that you'll keep adds to the floor height, so measure from the top of that strip, not underneath it.
Note any pipes, electrical conduits, or light fixtures that hang below the lintel inside the garage. These reduce your effective height and affect whether a roller door will fit when you consider headroom requirements in the next step.
Step 3. Check side room, headroom and backroom
Roller doors need more than just the right opening width and height to fit properly. The door mechanism, tracks, and motor require space on the sides, above, and behind the opening to operate smoothly. If you skip measuring these clearances when learning how to measure for a new roller door, you might order a door that physically fits the opening but cannot be installed because the hardware has nowhere to go. You need three specific clearance measurements before you finalise your roller door size.
Measure side room on both sides
Side room refers to the clear horizontal space between the edge of the door opening and the first obstruction on each side (walls, pipes, electrical boxes, or structural beams). Roller doors mount brackets and guide tracks on both sides of the opening, and these components need adequate space to fit without clashing with walls or utilities.
Measure from the inner face of each door jamb to the nearest obstruction on that side. Take measurements at multiple heights (top, middle, bottom) because walls aren't always straight. Record the smallest measurement for each side separately. Australian manufacturers typically require a minimum of 100mm side room for single garage roller doors and upto 250mm side room for double garage roller doors. The motor or drive side on large doors needs more room than the non-drive side, and drives can generally be installed on either side - but you need to specify this as looking out from inside.
If your side room falls short, you may need to relocate pipes or electrical fittings before installation.
Check both sides independently because garages often have different obstructions on each side. A hot water system on the left and a meter box on the right create different clearance challenges.
Measure headroom above the opening
Headroom is the vertical clearance from the top of your door opening (lintel) to the first obstruction above, such as the ceiling, roof trusses, beams, or light fittings. Roller doors coil into a drum that sits above the opening, and this drum needs enough space to accommodate the entire door when it's fully open.
Standard roller doors typically require 450mm of clear headroom for the drum, motor, and mounting brackets. Larger or heavier doors may need more.
Measure backroom depth
Backroom (sometimes called garage depth) is the horizontal distance from the inside face of your garage opening to any obstruction behind it, measured along the ceiling line. Roller door motors and control boxes mount inside the garage, usually to the side of the drum, and they need sufficient depth to clear stored items, cars, or workbenches.
Measure from the inside face of your door frame straight back along the ceiling to the nearest permanent obstruction (rear wall, storage shelves, or overhead beams). You need at least 450mm to 600mm of backroom, though specific requirements vary by door and motor model. Clear this space before installation day to avoid complications.
Step 4. Finalise your roller door size
You've gathered all your measurements, and now you need to convert them into a final door size for your order or quote. This step combines your opening measurements and overlap at the back of the opening, with the clearance checks to confirm which door size will fit your garage. When you follow how to measure for a new roller door correctly, most Australian suppliers require you to provide the finished Door Size, not the Opening size itself.
Determine your door dimensions
Take your largest width measurement and Highest height measurement from Step 2 as your finished opening size. For example, if your width measurements were 2405mm, 2400mm, and 2398mm, you'd use 2405mm. If your height measurements were 2102mm, 2100mm, and 2101mm, you'd use 2100mm. Your finished opening is 2405mm wide x 2100mm high.
Record your measurements using this template:
| Measurement Type | Dimension |
|---|---|
| Opening Width (smallest) | _______ mm |
| Opening Height (smallest) | _______ mm |
| Left Side Room | _______ mm |
| Right Side Room | _______ mm |
| Headroom | _______ mm |
| Backroom | _______ mm |
Cross-check these figures against the minimum clearances: 100mm side room (or 250mm for doubles), 450mm headroom, and 450-600mm backroom. If any clearance falls short, you need to address the obstruction before ordering your roller door.
Always use your smallest measurements to guarantee the door fits, not your largest or average figures.
Final steps
You've completed how to measure for a new roller door and have accurate dimensions recorded for your garage. Your measurements include opening width, opening height, side room, headroom, and backroom clearances. These figures give you everything needed to order the correct roller door size and avoid costly mistakes or delays.
Contact a roller door supplier with your measurements to request a detailed quote. Most Australian manufacturers require the finished Door Size dimensions rather than the door opening size itself, so provide your largest width and height measurements along with all clearance figures. They'll confirm whether a standard size fits or whether you need a custom-made door to suit your specific opening.
Ready to tackle the installation yourself? Check out our DIY roller door installation guide to see how straightforward the process can be and whether it suits your skill level.