How to calculate warp length and width
Begin with the washed, finished cloth you want. To allow for wet-finishing shrinkage, divide each finished dimension by 1 − shrinkage. Divide the pre-wash width by 1 − draw-in to estimate the width at the reed. For warp length, divide the pre-wash woven length by 1 − warp take-up, then add fringe, sampling, and loom waste before applying the extra-warp reserve.
These percentages are separate on purpose. Draw-in happens across the warp while weaving; take-up is warp consumed by interlacement; wet-finish shrinkage happens after the cloth leaves the loom. Combining them into one unexplained percentage makes it difficult to improve the next plan from a measured sample.
Sett, reed, and denting repeat
Total warp ends are the planned width in reed multiplied by target sett, rounded up, plus any entered floating or extra selvedge ends. The denting helper searches compact repeats of up to 12 dents. A repeat shown as 2–1–2 means two ends in the first dent, one in the next, and two in the third, then repeat. A zero means intentionally skip that dent.
Whole ends and whole dents can slightly alter width or sett. The result therefore reports both the target and the achieved sett, the number of dents used, and the resulting sleyed width instead of hiding the rounding.
How weft yardage is estimated
Pick count is the total woven length before washing multiplied by the planned picks per unit and rounded up. Each pick crosses the pre-wash cloth width. The separate weft take-up allowance adds yarn for its path around warp threads, and the extra-weft reserve covers joins, tails, bobbin waste, beat variation, and planning uncertainty.
If the warp and weft yarn labels provide yards per pound or metres per 100 grams, enter those rates to estimate each yarn’s weight. Yarn count systems, manufacturer labels, moisture, finishing, and scale accuracy can differ, so weight remains an optional purchasing estimate.
Sample before committing expensive yarn
This is a planning model, not a substitute for a washed sample. Structure, fiber, twist, sett, beat, loom, tension, selvedges, finishing method, and the weaver all affect take-up and shrinkage. Measure a representative sample, replace the default allowances with your observed values, confirm the reed width fits the actual loom, and keep enough yarn for repairs and sampling.
Frequently asked questions
Is width in reed the same as finished width?
No. Width in reed is normally larger because it includes expected draw-in during weaving and shrinkage during finishing.
Does loom waste get added for every piece?
No. Loom waste and the sampling allowance are added once for the whole warp. Fringe is added at both ends of every entered piece.
Why can the achieved sett differ from my target?
A real reed has whole dents and a warp has whole ends. The compact repeat and final partial repeat can shift the exact width or average sett slightly.
Can I use the same yarn-size number for warp and weft?
Only when they are actually the same yarn. Leave either optional field blank when its length-per-weight rate is unknown.
Browse craft tools · Text and data tools · All ToolQuill tools