Window Curtain Fabric Calculator — Advanced Full Options

Inputs

Units

Track / Rod width

Visible width to cover.

Pair or Single

Return left

Fabric returning to wall/end bracket.

Return right

Center overlap (for pair)

Fullness factor

Typical: 1.8 sheers, 2.0 standard, 2.5 luxe.

Usable fabric width

After selvedge; common is 137 cm (54").

Finished drop (top to bottom)

Header allowance

For heading/tape or grommets.

Bottom hem allowance

Vertical pattern repeat

Set to 0 if plain.

Shrinkage / relaxation

Ring / grommet spacing

Approximate spacing along the finished panel width.

Include lining

Lining bottom hem

Lining header

Lining shrinkage

Results

Face fabric

—

Total drops (widths): —
Drops per panel: —
Cut length per drop: —
Total length to buy: —
Area (approx.): —

Lining fabric

—

Cut length per drop: —
Total length to buy: —
Area (approx.): —

Hardware & counts

Panels: —
Finished panel width (each): —
Rings / grommets per panel (approx.): —
Total rings / grommets (approx.): —

All outputs rounded to two decimals. Always confirm with your fabric supplier’s bolt widths and repeats.

Example Data

Track width	Pair?	Returns (L/R)	Center overlap	Fullness	Fabric width	Finished drop	Header/Hem	Repeat
180 cm	Pair	7/7 cm	5 cm	2.0	137 cm	230 cm	10/20 cm	0 cm
240 cm	Pair	7.5/7.5 cm	5 cm	2.2	137 cm	240 cm	10/20 cm	20 cm
300 cm	Single	10/10 cm	0 cm	2.5	150 cm	260 cm	12/22 cm	32 cm

Formulas Used

Effective width (to cover) = track width + left return + right return + (center overlap if pair).
Panels = 2 if pair, else 1. Panel width = effective width ÷ panels.
Fullness width per panel = panel width × fullness factor.
Drops per panel = ceiling( fullness width per panel ÷ usable fabric width ).
Base cut length = finished drop + header allowance + bottom hem.
Pattern matching (if repeat > 0): cut length = ceiling( base cut length ÷ repeat ) × repeat.
Shrinkage: cut length ×= (1 + shrinkage% ÷ 100).
Total drops = drops per panel × panels. Total face length = total drops × cut length.
Lining (optional): same drops. Lining cut length uses lining header/hem and lining shrinkage.
Area (approx.) = total length (m) × usable fabric width (m).
Rings per panel ≈ round( fullness width per panel ÷ ring spacing ) + 1.

These are industry-standard approximations. Exact requirements may vary by heading style, workroom practices, and fabric behavior.

How to Use

Select units and enter the track or rod width to cover.
Choose pair or single panel, and set returns and overlaps.
Enter fullness, usable fabric width, finished drop, header, and hem.
Add pattern repeat and shrinkage if applicable. Toggle lining options.
Click Calculate. Review drops, lengths to buy, and hardware counts.
Export results as CSV or PDF for ordering or project files.

FAQs

What fullness factor should I choose?

Common choices: 1.8 for sheers, 2.0 standard living areas, and 2.2–2.5 for heavier, luxurious looks.

What if my fabric has a large vertical repeat?

Enable repeat and the calculator rounds each cut to the next full repeat, ensuring patterns align across drops.

How are returns and overlaps used?

Returns wrap fabric back to the wall or bracket ends; overlaps add extra width at the center for pairs.

Does lining change the number of drops?

No. Lining uses the same number of drops as the face fabric, but with its own header, hem, and shrinkage.

How accurate are the ring or grommet counts?

They are estimates based on spacing across the finished panel width. Always confirm hardware specifications for your chosen heading system.

Fullness Recommendations by Heading Style

Heading / Style	Typical Fabric	Look	Recommended Fullness (×)
Sheer rod pocket	Lightweight sheer	Soft waves	1.5 – 1.8
Tape/pleat (standard)	Medium cotton/linen	Everyday fullness	2.0
Grommet / eyelet	Medium–heavy	Deep folds	2.0 – 2.2
Pinch pleat (double)	Medium	Tailored folds	2.2 – 2.4
Pinch pleat (triple)	Medium–heavy	Lux volume	2.4 – 2.6
Blackout lined	Heavy drapery	Maximum coverage	2.2 – 2.5

Choose higher fullness for heavier fabrics or more opulent looks.

Standard Allowances, Returns & Overlaps

Element	Typical Value	Notes
Header allowance	8 – 12 cm	Depends on tape/grommet style
Bottom hem (face)	15 – 25 cm	Heavier fabrics use deeper hems
Lining header	6 – 10 cm	Usually slightly smaller than face
Lining hem	10 – 18 cm	Keep lining shorter than face hem
Return (each end)	7 – 10 cm	Wraps back to wall or bracket
Center overlap (pair)	3 – 6 cm	Extra for pair meeting at center
Pattern repeat (vertical)	0 – 64 cm	Round cuts to next repeat
Shrinkage allowance	1 – 3%	Natural fibers may vary more

Always confirm workroom standards and fabric behavior before cutting.

Common Fabric Widths & Drop Examples

Example shows drops per panel for a 140 cm finished panel width at 2.0× fullness.

Usable Width (cm)	Common Bolt Label	Drops per Panel (example)	Notes
127	50″	3	Often needs three drops
137	54″	3	Most common home drapery width
140	~55″	2	Two drops can suffice
145	57″	2	More coverage per drop
150	59″	2	Efficient for wider panels

Actual needs depend on your effective width and chosen fullness factor.

Tips & Notes

Usable width excludes selvedges; verify with your supplier.
For heavy fabrics, increase fullness and header allowances.
Lining often uses slightly smaller hems than the face fabric.
Pre-shrink or steam-press natural fibers when possible.
Round up yardage to the nearest whole meter or yard when ordering.