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:
|
Width |
Length |
On the loom |
8″ |
8.25″ |
Off the loom |
6.75″ |
7.5″ |
Take-up |
15% |
10% |
After finishing |
5.75″ |
6.5″ |
Shrinkage |
15% |
13% |
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).