Through the reed and heddles
When I was teaching my weaving classes, we had one session that covered how to calculate your yardage, so I thought we’d do a post about Yardage Calculation 101.
For me, calculating how much yardage I’m going to need for a particular project has been a matter – to an extent – of trial and error. I’ve learned to keep very detailed and accurate records of each project so I can duplicate it much more easily next time. The elasticity and shrinkage of your fiber has a huge impact on your calculations.
So, let’s go ahead and get started, shall we?
We’re going to calculate our warp length for a scarf made out of a superwash wool/wool blend.
Here’s our specifics:
Finished dimensions (meaning AFTER washing/drying) – 6” wide x 72” long.
Fringe – twisted – 6” long
e.p.i. (ends per inch) – 16
p.p.i. (picks per inch) – 14
When calculating warp length, I work backwards. You have to take into consideration the type of fiber you’re using, how much it will shrink, and how elastic it is.
Today, we’re using a superwash wool/wool blend that has a shrinkage factor of 10%, and very little elasticity.
If I want my scarf to end up about 72” long, I know I’ll need to actually weave it longer.
Here’s how I calculate it:
72” + 10% (7.2”) = 79.2”. I would round this up to 80” because when you subtract 10% from 80 you get 72.
For the fringe – if I want the finished length 6” – twisted – then I know I’ll need to start with about 7.5”. It will shrink up, and you’ll also lose up to 1” when you twist it.
Now for the width: If I want it to end up about 6” wide these are the factors I need to consider – draw-in and shrinkage. First, for draw-in – depending on how you weave, and what fiber you’re using, this will vary. For me, with a superwash wool/wool blend, I’ll be looking at about 1” of draw-in (about ½ inch on each selvedge), plus about another 10% of shrinkage.
6” + 1” + .75” = 7.75”. Depending on your pattern, you will adjust this accordingly.
Then, we need to determine how much loom waste we’ll have. This also varies between weaver and size of loom. For my table loom, I need about 6” on the front and 12” on the back. For my larger floor loom I need more on the back.
So, when we put it all together, this is what we have, starting at the front beam (these are all inches).
6 + 7.5 + 80 + 7.5 + 12 = 113/36 = 3.14 yards
So, each yarn end will need to be approximately 3.14 yards long.
Now, we need to calculate how many.
We already determined we need to start with 7.75” wide and the sett for the yarn we’re using is 16 epi.
Here’s your calculation: 7.75 x 16 = 124 ends (again, depending on your pattern, you may need to adjust this to fit your pattern repeat)
Total warp yardage needed: 3.14 yards long x 124 ends = 390 yards warp (rounded up)
*NOTE: when you’re measuring on your warping board, keep in mind that the more elastic the yarn is and the more you stretch it out across the pegs, the more draw up you’ll have – you may need to either increase the yardage a little, or stretch it less firmly.
Keep in mind this is a very simple way to figure how much warp yarn you’re going to need. If you’re using multiple colors – like stripes – you’ll need to figure each color separately.
If in doubt – make the warp a little longer and have some fun playing with what’s left over.
Also – a word to the wise – calculate, then calculate it again, then calculate it one more time. As in working with wood – once you’ve made your cut, you’re committed.