Measuring the sample before and after finishing gives me the rest of the data I need to calculate how much yarn I need to buy. The Handweavers Guild of America has has a great article on how to calculate this, which I’ve drawn from below.
Calculating the Warp
First, the calculations for take-up and shrinkage:
|On the loom||8″||8.25″|
|Off the loom||6.75″||7.5″|
Next, determining how many warp ends I need:
|Final planned width (“)||20″|
|+ Take-up (15%)||+ 3″|
|+ Shrinkage (15%)||+ 3″|
|= Width on the Loom||= 26″|
|x epi (ends per inch)||x 15|
|= Warp Ends||= 390 ends|
|+/- Adjustment for pattern||+2 (add balance threads)|
|= Total Ends to Wind||= 392|
Then I need to determine the length of each end:
|Final length (6 yards)||216″|
|+ Shrinkage (13%)||28.08″|
|+ Take-up (10%)||21.6″|
|+ Loom waste||36″|
|= Total warp length (rounded up)||302″|
This gives us the amount of yarn needed for the warp:
|Total Ends To Wind||392|
|x Length of each warp thread||x 302″|
|= Total warp needed (rounded up)||= 3289 yards|
Calculating the Weft
This is a much simpler calculation. Since I’m only doing a few decorative stripes of red (say, 12″ maximum), I will calculate as if the whole thing was orange.
|Width on the Loom (“)||26″|
|x Beat (shots/inch)||x 15 shots/inch|
|x Warp length for weaving (“)||x 302″|
|= Total weft needed in yards (rounded up)||= 3272 yards|
The Final Totals
I need 3289 yards of yellow wool, which rounds up to 15 balls of yarn.
I need 3272 yards of orange wool, which rounds up to 15 balls of yarn.
Plus 2 balls of red wool for decorative stripes.
At $3.39 a ball for yellow/red, and $3.59 a ball for the orange, my total cost for the yarn will be $111.48 US, plus tax/shipping. That boils down to $18.58 a yard (after finishing).