Measure a Square Bay Window for a Curtain Track

Pick your track fixing setup, then follow the short video and diagram for that option.

Every square (box) bay is a bit different — so I’ve split the guides by where your track will fix. Each section below shows you the exact measurements to take, with a quick video, a measuring diagram, and a downloadable template. When you’re done, enter your sizes on the Final Sizes form after ordering.

Ceiling in bay only

Usually used for deeper sills where curtains finish at or just below the sill inside the bay (no returns). Measure from the front lip of the sill between A–F as shown.

Diagram: square bay, ceiling-fixed within bay only, measuring points A to F — Diagram — ceiling fixed inside the bay only; measure from the sill lip.

Real bay with dotted lines showing sill-lip measurements — Real window — dotted lines mark the exact runs to measure.

Download measuring template (PDF)

Template is for guidance only. Enter your final sizes into the Final Sizes form after placing your order.

Wall in bay only

For when ceiling fixing isn’t possible; wall brackets mount inside the bay. Ideal for deeper sills and sill-length curtains.

Diagram: square bay, wall-fixed within bay only, measuring points A to F — Diagram — wall-fix within the bay; measure between points from the sill lip.

Real bay with dotted lines for wall-fixed inside bay only — Real window — dotted lines show section measurements.

Download measuring template (PDF)

Template is for guidance only. Enter your final sizes into the Final Sizes form after placing your order.

Ceiling in bay & Wall on returns

Room ceiling higher than bay ceiling: main run is ceiling-fixed in the bay; short returns fix to the walls. Include at least 20 cm of wall in each return.

Diagram: ceiling-fixed in bay, wall-fixed on returns, points A–F — Diagram — returns include sill end *plus* 20 cm wall allowance.

Real bay with dotted lines for returns including wall allowance — Real window — dotted lines show A→B and E→F return runs.

Download measuring template (PDF)

Template is for guidance only. Enter your final sizes into the Final Sizes form after placing your order.

Ceiling in bay and on returns

Bay and room ceilings level: ceiling-fix the entire track, including returns. Remember mouth (B→E) and diagonals (B→D, E→C) for accuracy.

Diagram: ceiling-fixed in bay and on returns, with mouth and diagonals — Diagram — full ceiling-fix; include B→E and diagonals B→D / E→C checks.

Real bay with dotted lines for full ceiling-fixed including returns — Real window — dotted lines mark sections and returns.

Download measuring template (PDF)

Template is for guidance only. Enter your final sizes into the Final Sizes form after placing your order.

Wall in bay and returns

No ceiling option: wall brackets used inside the bay and on returns. Include at least 20 cm of wall on each return for fabric stack clearance.

Diagram: wall-fixed within bay and on returns, points A–F — Diagram — wall-fix throughout; include wall allowance on returns.

Real bay with dotted lines for wall-fixed in bay and returns — Real window — dotted lines show each section measured from sill lip.

Download measuring template (PDF)

Template is for guidance only. Enter your final sizes into the Final Sizes form after placing your order.

Need Help?

We don’t sell blackout curtains themselves — we specialise in the tracks that make them effective. If you’d like tailored advice for your bay window, just send us a quick photo using the button below. We’ll be able to recommend the best track option for your setup. Or browse our bay window curtain track options.

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