How to Measure Your Patio for the Perfect Outdoor Blind Fit

Start with the right tools

Measuring seems like the simplest part of the whole project, but it is also where the most expensive mistakes happen. A blind cut 10 mm too wide will not fit. A blind cut 10 mm too narrow leaves an ugly gap. So before you do anything else, get the right tools: a steel tape measure (at least 5 metres long), a pencil, a notepad, and ideally a second person to hold the other end of the tape.

Avoid cloth or fiberglass measuring tapes — they sag and stretch. I once measured a 3.2-metre opening with a fabric tape and ended up with a blind that was 15 mm too narrow because the tape had stretched over time. That was a $280 lesson I will not repeat.

Step 1: Decide on mount type first

Before measuring, you need to know whether your blinds will be inside-mount (fitted within the opening, between posts or walls) or outside-mount (mounted on the face of the wall or beam, covering the opening). This decision changes how you measure.

Inside-mount looks cleaner and more integrated, but it requires the opening to be reasonably square and at least 60 mm deep to accommodate the headrail. Outside-mount is more forgiving of uneven openings and gives better coverage, but the blind protrudes from the wall surface. Most patio installations use outside-mount because pergola posts and beams are easier to screw into than narrow reveals.

Step 2: Measure width at three points

For inside-mount: measure the width at the top of the opening (just below where the headrail will sit), at the middle, and at the bottom. Write down all three numbers. Use the smallest one — this ensures the blind fits at the tightest point. Subtract 5 mm from that number as a clearance tolerance. That is your ordering width.

For outside-mount: measure the width of the opening, then add 50 to 100 mm on each side for overlap. So if your opening is 2400 mm wide, your outside-mount blind width would be 2500 to 2600 mm. The overlap prevents light bleed and wind gaps at the edges.

Step 3: Measure height at three points

Same principle — measure from the top mounting point to the desired bottom position at the left side, centre, and right side. For inside-mount, use the shortest measurement. For outside-mount, use the longest and add 50 to 100 mm at the bottom if you want the blind to overlap a floor or railing.

Think about where the bottom of the blind should sit. If it touches the ground, it will get dirty and potentially mouldy. If it stops 20 mm above the floor, you get a clean look without dragging. For blinds over a railing, stopping 50 mm below the rail top gives wind protection without interfering with the view when retracted.

Step 4: Check for obstructions

This step is easy to forget but critical. Walk around the opening and note anything that could interfere with the blind's path: ceiling downlights, beams, guttering, air conditioning units, power points, or decorative features. If a downlight is in the path of the headrail, you may need to move it or choose a slimmer bracket system. If a gutter runs along the top, outside-mount may not work without a custom bracket extension.

For zip screen blinds specifically, check that the side tracks have a clear vertical path. Any protrusion along the posts — like a bolt head or a surface-mounted conduit — will prevent the track from sitting flush. I have seen installations where the track had to be spaced 15 mm off the wall to clear a conduit, and it looked terrible.

Step 5: Double-check and photograph

Once you have all your numbers, measure again. This is not paranoia — it is insurance. A second measurement catches transcription errors and misread tape marks. Take photos of the space with your tape measure visible in the shot. These are invaluable if you need to discuss measurements with a supplier or if something arrives and does not fit.

Finally, draw a simple sketch of each opening with the measurements labelled. Note the mount type for each. When you order, refer to this sketch rather than your memory. Trust me — after measuring six openings, they all start to blur together.