Size curtains by width, drop, fullness, and hems. Compare panels, fabric widths, allowances, and coverage. Get neat estimates for stylish rooms without wasted material.
Use the responsive calculator below. Large screens show three columns, smaller screens show two, and mobile shows one.
These sample values show how different rooms can change fabric demand and panel planning.
| Room | Opening Width | Height | Fullness | Panels | Fabric Width | Estimated Total Fabric |
|---|---|---|---|---|---|---|
| Bedroom | 180 cm | 220 cm | 2.0x | 2 | 140 cm | 513.60 cm |
| Living Room | 260 cm | 245 cm | 2.2x | 2 | 140 cm | 1101.60 cm |
| Sheer Layer | 200 cm | 230 cm | 2.5x | 2 | 300 cm | 535.00 cm |
Track Width = Window Width + Left Overlap + Right Overlap
Finished Drop = Rod-To-Finish Height − Floor Clearance
Required Finished Width = Track Width × Fullness Ratio
Required Panel Width = Required Finished Width ÷ Number Of Panels
Usable Fabric Width = Fabric Width − (2 × Side Hem)
Widths Per Panel = Smallest whole number where joined width meets panel width after seam loss
Base Cut Drop = Finished Drop + Heading Allowance + Bottom Hem Allowance
Pattern-Matched Cut Drop = Base Cut Drop rounded up to the pattern repeat
Total Fabric Length = Total Fabric Widths × Cut Drop
Grand Fabric Length = Total Fabric Length + Waste Allowance
A ratio around 1.8 works for eyelet styles, while pleated curtains often look better between 2.0 and 2.5. Sheers usually need more fullness to avoid a flat look. The best choice depends on style, light control, and how rich you want the folds to appear.
Side overlaps help curtains cover the full opening, block more light, and make the window appear wider. Without enough overlap, panels may leave gaps near the frame and the treatment can look undersized. Many people use extra width for both function and appearance.
Usable fabric width is the fabric width left after subtracting side hems. It matters because not every centimeter or inch of cloth becomes visible curtain width. Hems and seams consume material, so usable width gives a more realistic estimate for how many fabric widths you need.
Use pattern repeat when the fabric design must line up across joined widths or matching panels. Stripes, florals, and large motifs often need this adjustment. The calculator rounds the cut drop upward so the pattern can align neatly instead of looking broken or shifted.
Waste percentage adds a safety margin for trimming, squaring fabric, pattern matching, cutting mistakes, and installation changes. Real projects often need more fabric than raw formulas suggest. Adding waste helps prevent shortages that can delay sewing or force you to reorder from a different dye lot.
Yes. Blackout curtains often benefit from generous overlap, solid fullness, and accurate floor clearance. If you also use lining or interlining, the visible size formula stays similar, though heavier fabrics may affect how full the finished curtain looks once hung.
Stack back is the space the curtain occupies when opened and pushed to the sides. A larger fullness ratio and more fabric widths increase stack back. This estimate helps you decide whether the open curtain will cover part of the glass or sit mostly off the window.
Measure both, but size the curtain around the intended coverage area. Many people begin with the window and then add overlaps to define the track width. If the rod is already installed, confirm its full length too, because that often becomes the practical finished coverage width.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.