How to Measure Your New Build Windows

Get it right first time — because new builds don't do standard sizes.

6 min read

Why measuring matters in a new build

Here's something that catches a lot of new build buyers off guard: your windows aren't standard sizes. Even within the same house, you might have three different window widths upstairs and two different depths downstairs. The "standard" sizes you see online rarely fit.

Measure wrong and you'll end up with blinds that don't fit, curtains that gape at the sides, or worse — you'll have to order again and wait another two weeks staring at bare windows.

Measuring for blinds — step by step

You'll need: a metal tape measure (not a fabric one), a pen, and a notepad. Measure in millimetres — it's more accurate.

Step 1: Decide recess or face fit. Inside the recess means the blind sits inside the window frame. Face fit means it sits on the wall above the window. Most new builds suit a recess fit.

Step 2: Measure the width. Take three measurements across the recess — top, middle, and bottom. Use the narrowest measurement. Your recess might not be perfectly square.

Step 3: Measure the drop. Take three measurements down the recess — left, centre, and right. Use the longest measurement so the blind covers the full window.

Step 4: Note any obstructions. Check for window handles that stick out, trickle vents at the top, or anything that might stop the blind sitting flat.

Measuring for curtains — step by step

Step 1: Decide where the pole or track goes. Typically 15–20cm above the window frame and 15cm wider on each side. In new builds with limited wall space between windows, you may need to adjust.

Step 2: Measure the width. Measure the full width of your pole or track (not the window). For fullness, most curtains need to be 1.5x to 2x this width.

Step 3: Measure the drop. From the top of the pole to where you want the curtains to finish. For floor-length curtains, measure to 1cm above the floor. For sill-length, measure to 1cm below the sill.

Step 4: Account for heading type. Eyelet curtains sit below the pole. Pencil pleat and pinch pleat hang from hooks above the track. This changes your drop measurement by a few centimetres.

Common mistakes to avoid

Using a fabric tape measure — they stretch. Always use a metal one.
Measuring once — measure three times across and three times down. Windows aren't perfectly square, even in new builds.
Forgetting trickle vents — those small ventilation strips at the top of new build windows can block a recess-fitted blind.
Mixing up recess and overall — "recess" means inside the frame, "overall" means the full width including frame. Getting these confused is the single most common ordering mistake.
Measuring in centimetres — most blind suppliers want millimetres. Don't round up.

Inside recess vs outside recess

Inside recess (recess fit): The blind sits inside the window frame. Clean, modern look. Works brilliantly in new builds with deep window recesses. Most Perfect Fit and roller blinds use this method.

Outside recess (face fit): The blind or curtain is mounted on the wall above and wider than the window. Better for covering up an ugly frame or letting in maximum light when open. The default for curtains on a pole.

For new builds, recess fit is usually the way to go for blinds. It looks neater, doesn't require drilling into walls (preserving your warranty), and suits the clean lines of contemporary windows.