Getting curtain measurements right matters more than most people expect. Knowing how to measure curtain length and width properly is the difference between a window treatment that looks tailored and one that leaves gaps, drags on the floor, or sits awkwardly above a radiator. I’m focusing on the practical details that actually affect the result: where to start measuring, how much width to allow, which drop suits each room, and what to check before you order.
Key measurements to get right before you buy
- Measure the pole or track, not just the window glass.
- Decide first whether you want sill length, below-sill, floor-length, or a puddled finish.
- Allow extra width for the heading style, brackets, and side coverage.
- Use a metal tape measure and take more than one reading on the drop.
- If the room has a radiator, leave clearance so heat can escape.
Measure the hardware first, because the glass is not the real width
I always start with the pole or track, because that is what the curtain actually hangs from. The window itself is only part of the picture, and measuring the frame alone is one of the fastest ways to end up with curtains that look short or leave light leaking at the sides.
- Decide whether the curtains will hang inside the recess or outside it.
- Measure the full width of the installed pole or track, excluding decorative finials.
- Write the measurement down as the hanging width, not the glass width.
- If the pole is not fitted yet, plan its position before buying the curtains.
For a neat UK-style installation, I usually aim for the pole or track to sit about 10-15 cm above the window and extend 15-20 cm beyond each side. That extra span makes the window look taller, lets the fabric stack back more cleanly, and improves light control. If you want the pair to meet neatly in the middle, a small centre overlap helps too.
Once that base width is right, the next decision is how low you want the fabric to fall.
Choose the drop that suits the room
The drop changes the whole mood of a room. A short curtain can feel crisp and practical, while a floor-length panel reads softer and more finished. I tend to choose the simplest length that still looks intentional, because that usually gives the best balance of style, cleaning, and longevity.
| Finish | How I measure it | Best for |
|---|---|---|
| Sill length | From the top of the pole or track to about 0.5-1 cm above the sill | Kitchens, bathrooms, and compact windows |
| Below sill | From the top of the pole or track to around 15 cm below the sill | Rooms that need privacy but still feel light |
| Floor length | From the top of the pole or track to about 1 cm above the floor | Living rooms, bedrooms, and most main spaces |
| Puddled | Floor length plus extra fabric so the cloth rests on the floor | More decorative rooms where softness matters more than easy cleaning |
If there is a radiator beneath the window, I leave roughly 3 cm of clearance above it so heat can move into the room instead of being trapped behind the fabric. I also take the drop in a few places if the floor is uneven, then use the measurement that avoids dragging. That is usually more practical than chasing a mathematically perfect number.
With the drop sorted, the next issue is how much fabric width you actually need for the heading style you choose.
Match fullness to the heading style
Width on the packet and fullness on the window are not the same thing. The heading style changes how the fabric gathers, and that is where many people underbuy. I prefer to think in terms of finished appearance rather than just the label on the pack.
| Heading style | Good starting point | What matters most |
|---|---|---|
| Eyelet | About 2 times the pole width | Works best on a straight pole and gives soft, even waves |
| Tab top | About 1.5 times the pole width | More casual, with less gather and less visual weight |
| Pencil pleat | Check the pack wording carefully | Some products quote width per curtain, others per pair |
| Pinch pleat or wave | Follow the supplier’s finished-width guide | More structured and less forgiving if the size is off |
If I want a room to feel calmer and more considered, I usually lean a little fuller rather than tighter. Curtains that are too narrow often look flat and cheap, even when the fabric itself is good. If light control matters, especially with blackout lining, width becomes just as important as the drop.
That brings me to the part that saves the most time in practice: reading the size label correctly before buying.
Read ready-made sizes carefully before you place the order
In the UK, ready-made curtains often come in common widths such as 117 cm, 168 cm, and 228 cm, with drops like 137 cm, 182 cm, and 228 cm. Those figures are genuinely useful, but only if you know whether the label refers to one panel or the pair, because different brands word that differently.
| Common size | Typical use | Why it works |
|---|---|---|
| 117 x 137 cm | Smaller windows or sill-length curtains | Compact and easy to manage in tighter rooms |
| 168 x 182 cm | Standard rooms and average windows | Flexible enough for many everyday installations |
| 228 x 228 cm | Wider windows or floor-length hanging | Better suited to taller rooms and a fuller look |
I also pause here if the room needs something more exact than a standard size can offer. Unusual window proportions, deep recesses, radiators, and very clean blackout requirements all push the job toward made-to-measure. That is not a luxury decision every time; sometimes it is simply the smarter way to avoid waste and repeated returns.
Once the size label makes sense, the next job is avoiding the mistakes that ruin an otherwise good measurement.
The mistakes that cause the most reorders
- Measuring the window glass instead of the pole or track.
- Forgetting decorative finials, brackets, or a centre overlap.
- Measuring before the hardware is fitted.
- Starting from the wrong point for the heading style.
- Ignoring radiators, skirting boards, or a sloping floor.
- Ordering before checking whether the width is quoted per curtain or per pair.
- Choosing puddled curtains in a high-traffic room where they collect dust and wear faster.
I see the last mistake a lot: people fall in love with a soft, luxurious look, then realise it is awkward to vacuum, kick, or clean. In a busy home, a floor-kissing finish usually gives a calmer result with less upkeep. That leads naturally to the final check I make before buying.
My final check before I buy curtains for a room
- The width is based on the installed pole or track, not the window frame.
- The drop is measured from the correct start point for the heading.
- The fullness suits the fabric and the way the room is used.
- The finish will not block heat, catch dust, or drag on the floor.
When I measure this way, the result feels intentional rather than forced. It also reduces waste, because I am less likely to return fabric, reorder the wrong size, or compromise with curtains that only almost fit. For most rooms, I still prefer a simple rule: measure the hardware carefully, allow enough fullness to let the fabric fall well, and choose the cleanest drop the room can live with. That is the most reliable way to get curtains that look settled from day one.
