Input variables
| Variable | Meaning | Unit |
|---|---|---|
| track | Track width | cm |
| full | Fullness ratio | times |
| drop | Finished drop | cm |
| hems | Total top and bottom allowance | cm |
| usable | Usable fabric width | cm |
| repeat | Vertical pattern repeat, 0 for none | cm |
Equations
Fabric widths required · widths
widths = ceil(track*full/usable)
Cut length per width · cm
cut = roundup(drop+hems,repeat)
Total fabric length · m
meters = widths*cut/100
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
- The calculator uses usable width after seam and side-hem deductions.
- Pattern-repeat rounding aligns vertical cuts but does not account for horizontal matching.
- Fullness depends on heading style and fabric behavior; use your hardware’s guidance.
- Lining and interlining are separate materials.
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.