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Article published at:
November 14, 2025
How to Measure a Bay Window for Curtains - Your Step-by-Step Guide
Avoid measuring mistakes - learn how to measure a bay window for curtains accurately and confidently, so your new window treatment fits like a glove.
Why Getting the Measurement Right Matters
Avoid the “too short or too narrow” nightmare
If you under-measure your bay window you’ll end up with curtains that … don’t quite reach or don’t fully close, leaving awkward gaps or light streaming where you didn’t want it.
Ensure full curtains that gather and stack neatly
Add enough width so that when your curtains are open, they can "stack" neatly at the sides, rather than blocking part of the view. Guides recommend adding at least 20-30 cm on each outer side.
Make the installation future-proof
When you measure well, you’ll choose the right hardware (pole or track), avoid nasty surprises when fitting brackets and get the aesthetic you’re after (think full-length drama, or modern neat finish).
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1: Identify What Type of Bay You've Got
Before pulling out the tape measure, it helps to know what sort of bay window you’re dealing with - because measurement varies slightly.
Angled bay vs box bay vs curved/bow bay
- An angled bay has window panels that meet at clear corners (e.g. 3-sided or 5-sided).
- A box bay is more rectangular or square outward-projection.
- A bow bay or curved bay has gentle curves rather than sharp angles.
Knowing this helps you decide whether you’ll use a bendable track, angled connectors or a rigid pole.
Decide hardware: curtain track or pole
As noted by bandaged guides, tracks (especially flexible ones) give more seamless movement around curves. Poles can work beautifully but need correct connectors and overhangs.
Shop our hardware range here to choose from our options.
Note the walls, returns, and side allowances
Check whether the bay returns onto short walls (so curtains can sit back on those walls) or whether there is little side wall to tuck behind. This affects how much overhang to allow.
2: Measure the Width – The Crucial Number:
This is the part where many people go wrong. Let’s break it down clearly.
Step-by-step for angled bay
- Using a rigid tape or a soft tape (for curved tracks) measure the width of each wall section of the bay: from the start of the pole/track on side wall to the angle, then across the next section, and so on.
- Add the widths of all sides together to get the total width your pole or track will cover.
- Allow for overhang – it’s advisable to extend the pole/track beyond the outer windows by about 15-30 cm (6-12 in) on each outer side so the curtains can be drawn back without blocking light
For curved or bow bays
If your bay is curved, you’ll likely use a bendable track. You should run a soft tape or piece of string along the curve from the start to end point to get the width across the curve.
Check for any finials, brackets or side limitations
When using a pole, check whether finials add length, or whether the wall ends abruptly thus restricting how far you can overhang. Some guides emphasise subtracting allowance if brackets take up length.
3: Measure the Drop – How Long Should Your Curtains Be
Once you know the width, next up is how far your curtains will drop – and of course you want it to look right.
Decide how you want your curtains to finish
Typical options in the UK:
- Above sill (just 1-2 cm above)
- Below sill (15-20 cm below)
- Floor length (1-2 cm above floor) – the most elegant for living rooms.
- Measure from correct fixing point
- For tracks: measure from the top edge of the track down. For poles: measure from the underside of the ring / eyelet (or where the curtain will hang). Some guides say measure from the top of pole then subtract a small allowance.
- Take three drop measurements
- Because walls/floors may not be perfectly level, take a measurement left, centre and right and use the shortest as your drop length. This avoids curtains hitting floor or bunching.
4: Practical Tips & Common Pitfalls to Avoid
Allow for furniture, radiators or sills
If you have a radiator under the bay window or deep sill, you might want curtains just to a sill length or slightly above radiator height rather than puddling on the floor. Many UK homes have this.
Bracket vs ceiling fix
If there’s less than ~15 cm above window frame to ceiling, a wall bracket may not fit and you’ll need a ceiling bracket for the pole/track.
Make sure your heading style is compatible
If using a track, some heading types (e.g., eyelets) may not work well because the hooks may snag at the corners in a bay. Good planning avoids that.
Don’t assume symmetry
Bay windows often aren’t perfectly symmetrical - each side could differ by a few cm. Measure each section individually rather than assuming “oh all five sides must be the same”.
Double-check everything
Yes, measure twice. Then check once more. While you’re already up on the stool. Because once you order your curtains or pole/track, changes may be costly or awkward. Ask someone to hold the tape if you can.
5: Now You’re Ready to Choose Curtains
With accurate measurements in hand, you’re well on your way to selecting curtains that fit beautifully.
Ready-made vs made-to-measure
If your bay window dimensions are non-standard (which many are), you might want to explore made-to-measure. But if they fall into common size ranges, our ready-made curtains collection may suit you.
Choose the right hardware for your measurement
For example, you might use the flexible net rod for large bay windows if your bay has unusual angles or you’re after a more subtle curtain solution. Installing the correct pole/track means your curtains will hang and move as intended.
