Input variables
| Variable | Meaning | Unit |
|---|---|---|
| edge | Attachment edge length | cm |
| ratio | Gather ratio | times |
| depth | Finished ruffle depth | cm |
| allow | Total height allowance | cm |
| join | Total length allowance | cm |
| fabric | Usable fabric width | cm |
Equations
Cut strip length · cm
length = edge*ratio+join
Cut strip height · cm
height = depth+allow
Width-of-fabric strips · strips
strips = ceil(length/fabric)
Fabric length required · cm
yard = strips*height
Notation
PI means π. ** means a power, sqrt means square root, and abs gives the absolute value. Trigonometric functions use radians. min and max select the smallest or largest argument.
ceil rounds upward, floor rounds downward, and round rounds to the nearest integer with halves toward positive infinity. roundup(value, step) rounds upward to the next multiple of the step; a zero step leaves the value unchanged.
Assumptions
- A ratio of 2 means two units of flat strip for one unit of finished edge.
- Lightweight and heavy fabrics produce different visual fullness at the same ratio.
- Height allowance must include your seam and hem or double-layer construction.
- This assumes the ruffle strips may be joined across fabric widths.
Precision and verification
The tool uses ordinary double-precision numeric arithmetic. Output is displayed to at most four decimal places; measurement precision is usually much lower. Check the worked examples, your project’s specifications, and a real sample before committing material.