Weaving Project Size From Yarn Calculator
Enter the yarn you have set aside for warp and weft, then add the sett, beat, shrinkage, waste, sampling, and fringe assumptions. The calculator estimates the maximum finished length and names the yarn supply that limits the project.
Maximum finished length67.7
- Limiting yarn
- Weft
- Warp ends
- 160
- Width in reed
- 13.33
- Warp length to wind
- 3.26
- Warp yarn used
- 520.82
- Weft yarn used
- 380
- Warp yarn remaining
- 79.18
- Weft yarn remaining
- 20
Length limits
| Yarn supply | On-loom capacity | Finished capacity |
|---|---|---|
| Warp | 85.74 | 77.16 |
| Weft | 75.23 | 67.7 |
Length values are inches; yarn quantities are yards.
Reserve is held back when finding the maximum length, then shown as remaining yarn if it is not needed.
Warp and weft are both reported as limiting when their on-loom capacities are within one-quarter inch.
How to use this calculator
- Enter the measured warp and weft yardage after separating the yarn you plan to use for each role.
- Enter the target finished width, warp sett, and expected picks per inch.
- Add draw-in, length shrinkage, warp take-up, weft take-up, loom waste, sampling, fringe, and reserve.
- Read the finished length, limiting yarn, winding length, yarn used, and yarn remaining.
How the project size is calculated
This calculator works backward from the yarn available. It treats the warp and weft as separate supplies, converts each to usable inches after the reserve, and asks how much on-loom cloth each supply can support. The smaller of those two lengths is the project limit.
Let Aw be 36 x warp yardage x (1 - reserve / 100) and Af be 36 x weft yardage x (1 - reserve / 100). The preliminary reed width is:
W = finished width / (1 - width loss / 100)
The number of warp ends is rounded up to a whole thread:
N = ceiling(W x EPI)
The adjusted reed width is Wr = N / EPI. Fixed warp length per end is F = loom waste + sampling length + 2 x fringe at each end. The warp-limited on-loom project length is:
Lw = max(0, (Aw / N - F) x (1 - warp take-up / 100))
For weft, each pick is longer than the straight reed width because of weft take-up:
P = Wr / (1 - weft take-up / 100)
The sample consumes sampling length x PPI x P inches of weft before the project length is considered. The weft-limited on-loom project length is:
Lf = max(0, (Af - sample weft) / (PPI x P))
The maximum finished length is min(Lw, Lf) x (1 - length shrinkage / 100). Warp used is based on the on-loom project length plus fixed allowances, adjusted for warp take-up. Weft used is the sampling length plus project length, multiplied by picks per inch and the yarn length per pick.
What moves the estimate most
Width, sett, and loom waste usually drive warp use. A wider finished target increases reed width, raises the number of warp ends, and increases the weft length per pick. A denser sett also increases the number of ends, so every inch of fixed waste and fringe is multiplied by more threads.
Picks per inch, weft take-up, and sampling length drive weft use. A firm beat can shorten the project quickly because each woven inch contains more picks. Sampling is counted before the project because those picks use weft even if the finished piece later becomes shorter.
What this calculator leaves out
The estimate assumes a rectangular project with one sett, one pick density, and one consistent width. It does not model pickup patterns, tapestry, clasped weft, pile, leno, differential shrinkage, frequent color changes, or extra loss from knots and joins beyond the reserve you enter.
The result also does not check whether the project fits your loom, reed, yarn strength, abrasion limits, or intended use. Measured take-up and shrinkage from a representative wet-finished sample are more reliable than defaults.
Worked example
Suppose you have 600 yards for warp and 400 yards for weft. You want a 12 inch finished width at 12 EPI and 12 PPI, with 10% width loss, 10% length shrinkage, 5% warp take-up, 5% weft take-up, 24 inches of loom waste, 6 inches of sampling, 4 inches of fringe at each end, and a 5% reserve.
The usable warp is 20,520 inches and the usable weft is 13,680 inches. The preliminary reed width is 13.333 inches, which rounds to 160 warp ends, so the adjusted reed width remains 13.333 inches. Fixed warp allowance is 38 inches per end. The warp supply could support 85.738 inches on the loom, while the weft supply can support 75.225 inches on the loom.
Weft is the limiting yarn. After 10% length shrinkage, the maximum finished length is 67.7 inches. The warp length to wind is 3.255 yards per end, using about 520.8 yards of warp and 380.0 yards of weft, with about 79.2 yards of warp and 20.0 yards of weft remaining.
Common questions
How do I calculate how large a weaving project my yarn will make?
Separate the yarn into warp and weft supplies, then calculate how much on-loom length each supply can support after waste, sampling, fringe, take-up, and reserve. The shorter capacity controls the project. This calculator does that comparison and then reduces the winning on-loom length for finishing shrinkage.
Why is warp or weft identified as the limiting yarn?
Warp and weft are consumed in different ways. Warp depends on the number of ends and the length wound for each end, including loom waste and fringe. Weft depends on picks per inch and the take-up-adjusted length of each pick, so either supply can run out first.
How do I measure warp and weft take-up from a sample?
For warp take-up, compare the warp length consumed on the loom with the woven length it produced before finishing. For weft take-up, compare the yarn length in a pick with the straight width across the cloth. Use the same yarn, sett, beat, and structure planned for the project.
What should I use for loom waste?
Use the measured unwoven warp your loom and method require for tying on, threading, knots, and the distance that cannot pass through the heddles or reed. Rigid-heddle looms often need less than many floor-loom setups, but the best number is the waste measured from your own loom.
Are draw-in and wet-finishing shrinkage the same thing?
No. Draw-in happens while weaving as the weft pulls the warp edges inward, and width shrinkage happens later during finishing. This calculator combines those width effects in one field, while length shrinkage is entered separately because it changes the final length after the on-loom limit is found.
Can I use the same yarn supply for both warp and weft?
Yes, but divide the total yarn between the warp and weft fields before calculating. The calculator assumes those two amounts are already allocated. If you are deciding how to split one yarn supply, try several splits and choose the one that leaves the least limiting remainder.