Curtain Fabric Yardage & Pattern Repeat Calculator
Plan fabric widths and cut lengths from rail coverage and fullness.
Include hems, pattern repeats and sales units, then save a cutting plan and budget in KRW.
Calculate windows using the same fabric, direction and sewing assumptions together. Dimensions are cm, fabric lengths are m, and prices are KRW. Defaults are fictional examples.
For vertical straight-match fabric. Whole widths are rounded up for each panel, with one extra pattern repeat reserved per window for the starting motif.
Fabric order and cutting plan
Fabric length to order
17.6 m
Sales units to order
176
Quoted fabric budget
264,000 KRW
Equivalent length: 19.2476 yd · One sales unit: 10 cm
- Total fabric widths
- 6
- Combined cutting length
- 17.28 m
- Repeat rounding within cutting length
- 168 cm
- Starting motif allowance total
- 32 cm
- Extra batch allowance
- 0 cm
- Required length before order rounding
- 17.6 m
- Sales-unit rounding surplus
- 0 cm
Cutting schedule by window
Each drop uses one full usable fabric width. The repeat-adjusted cut length is not the finished drop.
| Window | Panels | Widths/panel | Widths | Base cm | Cut cm | Start cm | Required m |
|---|---|---|---|---|---|---|---|
| #1 | 2 | 3 | 6 | 260 | 288 | 32 | 17.6 |
Window 1: 6 × 288 cm + 32 cm = 17.6 m
Flat width per panel: target / available after hems and seams: 300 / 406 cm
This estimate does not reuse surplus width. Reserving one repeat does not guarantee a particular motif position or horizontal seam match. Confirm usable width, pattern direction, continuous supply length, dye lot, allowances and sales units with the supplier.
Sources checked: 2026-09-18
Why curtain yardage is more than window area
Curtain fabric is purchased as a length of a roll with a specified width.
Multiplying window width by height misses fullness, hems, joining seams and fabric needed to match the pattern.
When a panel needs several fabric widths, even a small change in measurements can require another full drop.
This calculator helps home sewers and customers buying fabric for a maker plan the widths and length for each window.
Combine windows only when they use the same fabric, direction and sewing assumptions.
It produces a purchasing worksheet to review with the supplier and maker, rather than a final manufacturing instruction.
Dimensions use cm, order lengths use m and equivalent yd, and all entered prices and budgets use KRW.
Enter rail coverage, finished drop and fullness
Measurements for each window
Rail width means the total coverage you want.
Include returns and centre overlap agreed with your maker.
Finished drop is the final curtain height, excluding heading and bottom hem allowances.
Decide on hardware position and floor clearance before measuring from a consistent reference point.
A shared fullness multiplier
Fullness describes how wide the flat fabric should be relative to the coverage width.
The appropriate multiplier depends on the fabric and heading style; ask your maker.
Two panels divide the target width equally.
For unequal panels, enter their individual coverage widths as separate one-panel rows.
Enter up to 20 windows.
Inputs accept two decimal places, but this does not establish measurement accuracy.
Check installation tolerances and avoid listing the same window twice.
Different fabrics or sewing arrangements should be calculated in separate batches.
Separate usable fabric width from sewing allowances
The advertised width may include material you cannot use.
Enter the width remaining after selvages and any horizontal pattern-matching loss have been excluded.
The calculator does not lay out horizontal motifs; confirm this usable width with the supplier.
Joining seam allowances are then deducted separately.
Which allowance goes where?
- Heading and bottom allowances are the total material consumed by the folds.
For a double fold, include both folds rather than just the visible finished hem. - The outer hem allowance applies to both outside edges of each finished panel.
It is deducted twice per panel, not twice from every fabric width. - A seam allowance is entered per joined edge.
Each join consumes twice this value because both pieces contribute an edge.
Changing the sewing method can change the quantity for the same window.
A wider fabric must still suit vertical cutting and the intended pattern direction.
Usable width must exceed twice the joining seam allowance or calculation is blocked.
Full-width and pattern-repeat formulas
1. Round full widths per panel
Let W be rail coverage, F fullness, P panel count, U usable fabric width, h outer hem per side and s seam allowance per joined edge.
Target flat width per panel is W×F÷P.
Widths per panel n = max(1, ceil((W×F÷P + 2h − 2s) ÷ (U − 2s))).
This is the smallest integer for which nU − 2s(n−1) − 2h covers the target.
2. Round the vertical cut length
Base length L = finished drop + heading allowance + bottom allowance.
With vertical repeat R, cut length C = ceil(L÷R)×R.
For plain fabric, enter R=0 and C=L.
An exact repeat multiple is retained without adding another repeat.
3. Add start allowance and round the order
Required length per window = total widths×cut length + start allowance.
One repeat is reserved per window for the starting motif; plain fabric reserves zero.
Sum the windows, add the extra batch allowance once, then divide by the sales-unit length and round up.
Fabric budget = sales units×price per unit.
Each panel is rounded to whole fabric widths.
There is no half-width sharing between panels, so this can require more material than an optimized half-width layout.
Surplus width is not reused or deducted from the order.
Explain these assumptions when comparing the result with a maker’s cutting plan.
How to use the calculator
- Confirm vertical cutting, straight matching, usable width and vertical repeat from the sample and specification.
Leave the order unconfirmed if the pattern type is unknown. - Enter the rail coverage, finished drop and panel count for each window.
Write the row number on your measurement notes to identify each window in the saved plan. - Enter fullness and sewing allowances.
Remove any hems already included in the finished-drop measurement to avoid counting them twice. - Enter the length and price of one sales unit.
Add a separate batch allowance if agreed, but do not treat it as a shrinkage prescription. - Calculate, review each window and save the TXT worksheet.
Editing inputs clears the previous result so you can calculate a fresh plan before sending it.
Restore the fictional example to explore how changing one input affects the result.
Its allowances and prices are not recommendations or current market averages.
When comparing quotations, keep dimensions, fullness and included sewing services consistent.
Worked example: 300 cm rail and 230 cm finished drop
Assume fullness 2, two equal panels, usable width 140 cm, outer hems 4 cm per side and seams 1.5 cm per joined edge.
Heading allowance is 10 cm, bottom allowance 20 cm and vertical repeat 32 cm.
There is no extra batch allowance; the fictional quote is KRW 1,500 per 10 cm.
Widths and cuts
The target is 300 cm per panel.
Two widths provide only 269 cm after hems and seams; three provide 406 cm.
Each panel therefore needs 3 widths, or 6 widths in total.
Base cut length is 260 cm, rounded to 288 cm for the 32 cm repeat.
Order and budget
6×288 = 1,728 cm of cutting length.
Add a 32 cm start allowance to obtain 1,760 cm, or 17.6 m.
Order 176 units of 10 cm for KRW 264,000.
The repeat-rounding increment already included in the cutting length is 168 cm.
With identical settings but plain fabric, repeat rounding and the start allowance disappear, giving 15.6 m.
This difference is specific to these dimensions.
Patterned fabric does not always require the same percentage of extra material; it depends on the relationship between drop and repeat.
Interpret required length, ordered length and surplus
Required length combines the cutting plan and allowances.
Ordered length rounds this amount to the seller’s sales increment.
Sales-unit rounding surplus is only the difference between these lengths, not every offcut left after sewing.
Unused width, pattern trimming and hem material are different quantities.
Avoid counting allowances twice
Combined cutting length already includes the repeat-rounding increment.
Do not add that separately displayed increment to the order again.
Start allowances and the extra batch allowance sit outside the cutting subtotal and are included in required length.
Available flat panel width may exceed the target because the model purchases whole widths.
Your maker decides whether to trim the surplus or adjust gathering.
That flat width is not the installed coverage width; installation still depends on the rail and heading arrangement.
Compare multiple windows and selling units
One fabric for several rooms
Different drops can round to different repeat-adjusted cut lengths.
Each row is calculated before lengths are combined.
One start allowance is kept per window, while sales-unit rounding happens only once for the whole batch.
If the supplier divides the order across rolls, confirm each continuous piece separately.
Different fabric widths
A wider fabric may need fewer drops but cost more per metre or require a different cutting direction.
Calculate each product separately and compare both total budget and suitability.
Price per metre alone can be misleading when the supplied fabric widths differ.
One metre is 100 cm and one yard is 91.44 cm.
Yards here are a linear conversion, not an area unit.
Confirm the actual length behind a seller’s local unit name and any minimum order.
A unit price of zero means unknown: quantities remain available, but no budget is stated.
Check conditions outside this model
- Half-drop patterns require an offset layout between adjacent widths.
Do not use straight-match mode as a substitute; half-drop selection blocks the result. - Railroad cutting and curved windows do not follow this vertical rectangular-drop model.
Unconfirmed direction also blocks the result; discuss fabric nap and orientation with the maker. - Shrinkage depends on the material, finishing and care process.
Extra allowance does not calculate shrinkage or guarantee dimensions after washing. - Lining and sheers are separate fabrics.
Calculate their widths and allowances independently rather than copying the face-fabric length. - Shipping, sewing, hardware and additional tax are not automatically added.
Check which items your quotation already includes.
Frequently asked questions
Is fullness always twice the rail width?
No.
Use the multiplier agreed for the fabric and heading style.
The default only illustrates the calculation.
Can I divide the total widths equally between two panels?
The model rounds whole widths for each panel first.
A layout sharing half widths can produce a different quantity and needs a separate cutting plan.
How do I enter plain fabric?
Set vertical repeat to zero.
Base cut length is retained and no starting motif allowance is added.
Why reserve one repeat for each window?
It conservatively allows space to locate the starting motif for each window.
Actual consumption may be lower, while split rolls may require a separate review.
Does it position the same flower on every panel?
No.
It rounds vertical cut lengths to repeat multiples.
Motif centring and horizontal seam alignment still require inspection of the actual fabric.
What if my seller uses a local unit name?
Enter its confirmed length in centimetres and its matching price.
Do not assume a local unit automatically means one international yard.
Can ordered length exceed a roll length?
The total can be calculated, but continuous supply is not guaranteed.
Ask the supplier about roll splits and dye lots using the saved worksheet.
Can I calculate before receiving a price?
Yes.
Leave unit price at zero to calculate length and sales units.
The budget remains unspecified until a price is entered.
Sources and calculation assumptions
Sources checked: 2026-09-18.
This is a dimensional purchasing model using your quotation, with no statutory rates or standard construction prices.
These references explain specification and ordering concepts; they do not establish the fictional price or universal sewing allowances.
- Sailrite Window Curtains calculator: distinguishes finished drop, hems, fabric width, fullness and vertical repeat.
- John Lewis fabric specification: the checked example lists 142 cm width, 36 cm repeat, straight matching and 30 m roll length separately.
Use the current specification for the product you actually order. - Sailrite fabric ordering FAQ: explains linear yards, continuous pieces, roll length and possible fabric flaws.
Save the plan and confirm it with your supplier
Match window numbers to your measurement notes and save the cutting and order TXT.
Confirm product identity, usable width, repeat, direction, continuous length and dye lot with the supplier, and fullness and sewing allowances with your maker.
If a quotation differs, compare whole-width rounding, half-width sharing and starting allowances first.
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