A Practical Guide to Measuring Your Windows

· 5 min read
Measuring a window for custom curtains

Getting accurate window measurements is the single most important step when ordering custom curtains. Even the finest fabric will look wrong if the width is too narrow or the drop falls short. The good news is that measuring your windows is straightforward once you know what to look for. This guide walks you through the entire process so you can order with confidence and avoid costly remakes.

Whether you are fitting curtains for the first time or replacing an existing set, taking ten minutes to measure properly will save you a great deal of frustration later on. Grab your tools, follow the steps below and you will have everything you need to place your order.

Tools You Will Need

Before you start, gather these four essentials. Having everything to hand means you will not need to stop halfway through and hunt for a pencil.

  • Steel tape measure — a retractable metal tape is far more accurate than a fabric one. Aim for a tape that is at least three metres long so you can measure wide windows in a single pass without joining two readings.
  • Step ladder — you will need to reach the top of the window frame or ceiling comfortably. Standing on tiptoes leads to wobbly measurements, so use a stable step ladder and position it squarely in front of the window.
  • Pencil — mark light reference points on the wall or frame as you go. A pencil mark is easy to rub off later and gives you a visual anchor if you need to double-check a reading.
  • Notepad — write down every measurement as you take it. Label each window clearly, especially if you are measuring multiple rooms in the same session. Relying on memory is how mistakes happen.

Measuring the Width

The method you use to measure width depends on whether you plan a recess fit or a face-fix installation. Both approaches are common and each has its advantages, so decide which suits your window before you pick up the tape.

Recess Mounting

A recess mount sits inside the window opening. Measure the width of the recess at three points — top, middle and bottom — and use the narrowest reading as your final width. Window openings are rarely perfectly square, and taking the smallest measurement ensures the track or rod will fit without forcing it into place. For recess-mounted curtains you generally do not need to add any extra width because the fabric will sit within the frame.

Face-Fix Mounting

A face-fix mount positions the track or rod on the wall above and beyond the window frame. Start by measuring the width of the window opening, then add between fifteen and twenty centimetres on each side. This extra allowance lets the curtains stack back clear of the glass when open, giving you maximum light and making the window appear wider. If your window is next to a wall or a corner, adjust the allowance on that side to whatever space is available.

Whichever method you choose, always measure in millimetres for precision. Rounding to the nearest centimetre might seem harmless, but across a wide window those small differences add up and can leave visible gaps or bunching.

Measuring the Drop

The drop is the vertical measurement from where the curtain will hang to where you want it to finish. There are three common finish points and each creates a different look.

Ceiling to Floor

For a dramatic, floor-length look, measure from the ceiling — or from the top of a ceiling-mounted track — straight down to the floor. Subtract about one centimetre to prevent the fabric from dragging on the ground. This small clearance keeps the hem clean and allows the curtain to move freely along the track.

Architrave to Sill

If you prefer a more traditional appearance, measure from the top of the architrave to the bottom of the window sill. Add roughly ten to fifteen centimetres below the sill so the curtain overlaps the sill edge and blocks light leakage from underneath. This approach works well in kitchens or studies where floor-length curtains would get in the way.

Floor Clearance

Some homeowners like their curtains to just kiss the floor, while others prefer a centimetre or two of clearance. A slight puddle of fabric on the floor can look elegant in formal living rooms but is less practical in high-traffic areas. Decide on your preferred clearance before measuring and factor it into your final drop figure.

Measuring for Different Track Types

The type of track or rod you use affects where you take your measurements. A ceiling-fixed track means measuring from the ceiling itself. A wall-mounted rod with decorative brackets means measuring from the top of the rod, not the bracket. If you are using a bay window track that bends around corners, measure each straight section individually and note the angles. Our team can help you work out the total track length from those individual readings.

For double tracks — where a sheer and a blockout layer each have their own rail — measure the drop from each track separately. The front and rear rails may sit at slightly different heights, which means the two curtain panels could need different drop measurements.

Common Mistakes to Avoid

Years of helping customers with their orders have taught us which errors come up time and again. Steer clear of these and you will be well ahead.

  • Measuring only once — always take each measurement at least twice and compare the readings. If they differ by more than a couple of millimetres, measure a third time.
  • Using a fabric tape — fabric tapes stretch over time and can give readings that are several millimetres off. A steel tape is the only reliable option.
  • Assuming all windows are the same size — even windows that look identical can differ by a centimetre or more. Measure every window individually, even in the same room.
  • Forgetting the stack-back space — if you do not allow enough room beside the window for the curtain to stack when open, the fabric will cover part of the glass and block light during the day.
  • Ignoring obstructions — check for radiators, air-conditioning units or deep sills that could interfere with the curtain drop. Note any obstructions on your measurement sheet so they can be accounted for when ordering.

Tips for Tricky Windows

Bay Windows

Bay windows curve or angle away from the wall and require a flexible or segmented track. Measure each flat section of the bay separately and record the angle between sections. Most bay windows use either a three-section or five-section track. If you have a curved bay, a bendable track is the best option — measure the total arc with a flexible tape pressed against the window head and let us know the depth of the bay from the wall line to the front glass.

Corner Windows

When two windows meet at a corner, you need to decide whether the curtains will share a continuous track or run on two separate tracks with a gap at the corner. A continuous track gives a sleek, uninterrupted look but requires a specialist corner bracket. Separate tracks are simpler to install and let you operate each curtain independently. Measure each wall section from the corner outward and include the depth of the window frame so we can recommend the right bracket configuration.

No matter how unusual your windows are, accurate measurements are the foundation of a great result. If you run into any difficulty, take a few photos and send them through with your measurements — our team reviews every order before production begins and we will flag anything that looks off.

Ready to get started? Visit our installation guide for fitting tips, or book a free design consultation and let our specialists help you choose the perfect curtains for your home.