How Many Curtain Panels Do I Need? Measuring Curtains for a Thai Condo

Why curtains matter more in Thailand

West-facing condo glass can turn a room into an oven by late afternoon. Bedrooms facing the morning sun get bright very early. Full-width, floor-length blackout or thermal curtains help on both counts, and they make your aircon's job easier.

Step 1: measure the span and the drop

Span: measure the length of the rail or pole that the curtain can actually travel along. Leave out decorative end caps (finials). If the rail isn't fitted yet, take the window width and add an overlap on each side. Extending 15–20 cm past each side of the window blocks more light at the edges.

Drop: measure from where the curtain will actually hang (the ring, hook or track) down to where you want the hem. Eyelet, ring and track curtains start at different heights, so follow the measuring guide for the product you're buying.

Step 2: flat width or finished width?

This is the most common mistake. Check which width the listing gives:

Flat fabric width (before gathering): the calculator multiplies your span by the fullness, with 2× as the editable default, then divides by the width of each panel.

Finished width (already pleated): the calculator uses your span as it is. Don't add fullness again, or you'll buy twice as many panels as you need.

Example: condo window 180 cm wide, extending 15 cm each side

Span = 180 + 2 × 15 = 210 cm

Flat panels 140 cm wide, 2× fullness: 210 × 2 = 420 cm of fabric

420 ÷ 140 = 3 panels

For a split pair that opens in the middle, the calculator rounds up to an even number → 4 panels

Sold as pairs → 2 packs

Step 3: check the length

The calculator compares the product's length with your drop. A 250 cm curtain against a 240 cm drop is 10 cm longer, which is room to hem, or a reason to hang the rail slightly higher. Take shrinkage and how the fabric hangs into account before you cut anything.

Buying tips

Pack size: check whether a pack is one panel or a pair.

Heading fit: check that the heading (eyelets, hooks, pleats) fits your rail.

True blackout: look for blackout lining described in the listing rather than "dim-out".

Bright rooms: light leaks around the sides and top, so a wider span and a rail fitted above the window frame help.

Renters: ask before drilling. Many leases need the landlord's agreement for new rails.

FAQ

Do finials count in the rail width? No. Measure only the length the curtain can travel.

My panel is 10 cm too long. Do I cut exactly 10 cm off? First check the hanging point, how much the fabric might shrink, and how it will be hemmed.