Input variables
| Variable | Meaning | Unit |
|---|---|---|
| waist | Finished panel width | cm |
| n | Number of pleats | pleats |
| depth | Underfold depth per side | cm |
| allow | Total edge allowance | cm |
Equations
Visible width per pleat · cm
pitch = waist/n
Hidden fabric per pleat · cm
intake = 2*depth
Flat cut width · cm
flat = waist+n*intake+allow
Repeating marking distance · cm
mark = pitch+intake
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
- Underfold depth is the hidden return on one side of a knife pleat; total intake is twice that depth.
- The model assumes identical pleats across the entire finished panel.
- Closures, darts and unpleated sections should be removed from the target width and added separately.
- Fabric thickness can alter how tightly pleats lie.
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.