How to Plan and Measure for New Curtains and Hardware: A Step-by-Step Guide

Planning & Measuring for Curtains on New Tracks or Poles

The practical guide to getting it right first time.

Getting your measurements right at survey stage is non-negotiable. A few millimetres out can mean curtains that don’t sit properly, tracks that won’t fit, or fabric that feels skimpy.

This guide walks you through the professional method we use when planning curtain tracks and poles.

A quick note on measurements

We recommend measuring in millimetres (metric) for the most accurate results. Millimetres allow for precise ordering and reduce the risk of rounding errors.

If you prefer to work in feet and inches, that’s absolutely fine — just make sure that whoever is making or supplying your curtains is using the same unit of measurement. Mixing metric and imperial measurements is one of the most common causes of ordering mistakes.

1. Preparation: Tools & Standards

Before you even extend the tape measure, make sure you’re set up properly.

Use the Right Equipment

• Metal (steel) tape measure only – fabric or plastic tapes stretch and are not accurate enough.
• Step stool or ladder – you must be able to reach mounting height comfortably so the tape stays level.
• Notebook or phone notes – record everything immediately. Never rely on memory.
  

The Rules We Always Follow

1. Measure in millimetres (mm): This avoids rounding errors and matches how tracks and poles are manufactured.
2. Always measure width first, then drop: It sounds simple, but this consistency prevents ordering mistakes later.
3. Measure windows in the room from left to right: This means you always know where you started. 
4. Name your room: This sounds obvious but if you are doing multiple rooms with multiple windows, it helps!

2: Decide Where Your Curtains Will Sit

First decide whether your curtains will hang from:

• A curtain pole, or

• A curtain track

And whether they will sit:

• Inside the window recess, or

• Outside and above the window frame

Most curtains are fitted outside the recess to make the window appear larger and allow more light in when open.

As a rule of thumb, poles or tracks are usually installed 15–20 cm above the window and extend 15–30 cm beyond each side but this will depend on the space you have and if the window is centred in the wall or off to one side. 

Remember to check for lintels, electrics and plumbing restrictions. 

3. Measuring Standard Windows

3.1 Inside the Recess

Usually

Walls are rarely straight. Plaster can go awry  - this will affect how a blind can travel in the space. If you are measuring for café curtains, you need to measure where you want to fit the pole - this becomes your top measurement. 

You must take six measurements:

Width

• Top
• Middle
• Bottom

Drop

• Left
• Centre
• Right

✔ Record all six measurements.
✔ Use the smallest width and the smallest drop when ordering.

This prevents rubbing against uneven walls or sills.

3.2 Outside the Recess

• Measure the window opening width
• Measure Left Hand Stack Back (wall to left of window)
• Measure Right Hand Stack Back (wall to right of window)

Work out an even stack back for each side, this will depend on how central the window is and how much light you want to block. 

As a guide, add:

• 30–60cm total  (15–30cm each side for stack-back)

• This allows curtains to stack neatly when open.

• Write this number down as your track or pole width.

This is what we use, you might find it useful!

Measuring an Angled Bay Window

OK, are you ready? Bay windows require careful measuring because every angle matters.

Step 1: Label each corner

Stand facing the bay and label each corner point A, B, C, D (E, F etc as needed) from left to right. Write these letters clearly on your notes.

Step 2: Measure all straight sections

Measure the straight distance between each neighbouring corner:

• A → B

• B → C

• C → D

Record each measurement clearly. These are the individual wall sections.

Step 3: Measure the cross measurements (very important)

To ensure accuracy, you must also measure across the bay:

• A → C

• A → D

• B → D

• A → D

These diagonal measurements confirm that the angles and overall geometry are correct and are essential for bespoke tracks or poles.

Step 4: Check the angles

For each corner:

1. Place a sheet of paper tightly into the corner.

2. Fold the paper so the fold mirrors the exact wall angle.

3. Carefully remove the paper, keeping the fold intact.

4. Use a protractor to measure the angle created by the fold.

5. Write the angle next to the relevant corner letter.

Repeat this for every corner in the bay.

Measuring a Curved Bay Window

So this is where is gets a little trickier...

Curved bays are measured slightly differently to capture the depth of the curve accurately.

Step 1: Mark key points

Label:

• A = left end of the bay

• B = right end of the bay

• X = centre point of the curve

Step 2: Measure the span

Measure the straight distance A → B.

Draw an imaginary straight line between these two points. Find the midpoint of this line — this point is XX, which should align with your centre point X.

Step 3: Measure the depth of the curve

From the A–B line, measure straight into the bay at XX to find the maximum depth of the curve.

Step 4: Plot additional points

We recommend measuring depth every 10 cm along the A–B line. At each interval, measure from the line back to the wall to map the curve accurately.

Important: always measure to the wall itself, where the hardware will be installed not to skirting boards or coving, as these can distort the true shape of the bay.

The more points you plot, the more accurately a curved track can be manufactured.

Step 3: Understand Curtain Fullness

Curtains should be wider than the pole or track to create soft folds. Hand made and bespoke items take this into account, a ready made item will use less fabric.

Note: a ready made pencil pleat tape curtain is often marked with the size of the fabric and not the final size you will get once you have pulled the cords to create the pleats. 

A good guide is:

• 2× fullness for a classic, tailored look

• 2.3 - 2.5× fullness for a fuller, more luxurious feel

Example:
If your pole is 200 cm wide and you want 2× fullness, you’ll need 400 cm of total curtain width.

This is usually divided into two equal panels to give you a pair of curtains. 

Step 4: Measure the Drop (Length)

To get your drop, you will need to decide on the heading you want. The drop is measured from the top of the pole or track  or from the suspension point  down to where you want the curtains to finish. We recommend fitting the hardware to check the drop. 

There are three common options:

Sill length

Curtains finish just above the windowsill (about 1–2 cm above).

Below sill

Curtains fall 10–15 cm below the sill for a softer look.

Floor length (most popular)

Measure to the floor and subtract:

• 1–2 cm for a clean hover

• Exact drop to 'kiss' the carpet

• Or add 3–5 cm for a gentle puddle

Always measure in several places across the window, as floors can be uneven. Use the shortest measurement if you want curtains to hover neatly.

Step 5: Double-Check Your Measurements

Before finalising:

• Re-measure width and drop 

• Check you measured from the correct starting point (top of track or pole)

• Confirm your chosen curtain style and heading

A second check prevents expensive mistakes

Common Measuring Mistakes to Avoid

• Measuring only the glass, not the full window area

• Forgetting to add stacking space at the sides

• Ignoring curtain fullness

• Measuring from the wrong starting point

• Assuming floors are perfectly level

• Don't assume the same size windows in the same room are the same - plaster varies, stack-backs vary and recesses really vary!

Taking an extra few minutes here makes all the difference.

Quick Measuring Checklist

✔ Measure total pole or track width

✔ Think about curtain fullness (2× or 2.5×) - different headings use different quantities of fabric, this is a guide for a pencil pleat heading. 

✔ Measure drop required 

✔ If measuring inside a recess, measure in three places and use the smallest number

✔ Check measurements in multiple places

✔ Write everything down clearly

Final Thoughts

Well-measured curtains frame a room beautifully and elevate the entire space. If you’re unsure at any stage, professional measuring can save time and ensure a flawless finish — especially for bespoke soft furnishings.

Accurate measurements are the first step toward curtains that look intentional, elegant and perfectly proportioned to your home.

If you need help, get in touch to check we can travel to your home 

And once you have all these, do you want plain or a pattern?