Double Width, Single Rigid Heddle Series Part 1: Time for Math!

Hello, weavers! This blog post is part 1 of a series I am doing of a very detailed, step by step tutorial on how to do double width weaving with a singe rigid heddle. 

This blog series is accompanied by a video series that goes into more detail. You can find that video link at the bottom of this page or by clicking HERE

Step One: Calculating for “L” the width of your warp on the loom

First you need to figure out what kind of yarn/ thread you want to weave with and what dent heddle you want to use. If you are not someone who regularly samples, I strongly suggest you use a yarn that you have worked with before, especially if this is your first time weaving double width. Further I suggest you plan to use 2 colors, one for the top layer and a highly contrasted color for the bottom layer.

Once you have figured out what your materials and heddles are going to be you have to determine the FINAL dimensions you want your project to have. This is what you want it to measure after you take it off the loom and wet finish it. 

Then plug that number into the following formula:

(X/0.9) / 0.9 = L

Where X is the final width you want your project to be and L is the width you need to warp your loom.

On the calculator you put in your final width (X) then divide by .9 then divide by .9 again.

Make sure the number you get for L will fit on your loom! Since we are doing double width. Divide L by 2 and measure your heddle to make sure you can get that amount on it. (Don’t assume that a 20” loom has 20” of rigid heddles. Many looms are marketed as having a wider weaving width than they actually do because of converting over from Metric to Imperial units.)

Before moving onto step 2, you need to calculate Lv. Lv is the vertical length (on loom) of your warp. So think again of what you want your final length dimension to be after wet finishing (not accounting for fringe, we'll do that in the next step). Then, run the calculations again and write this number down.

Step 2: Calculating “W” the length of the warp

Take the number we calculated above  for “Lv” and add 12 to it. This accounts for about 6 inches of loom waste to tie on to the front and back beam of your loom. If your loom usually has more waste that that, adjust accordingly. 

This formula is super simple:

Lv + 12 = W

But, if you want a really long fringe (longer than 4 inches) it is best to add a bit extra to W at this step. 

Step 3: Calculating total yardage

Now it is time to calculate the amount of yarn/ thread you need to buy. Here is the formula for that:

((L xH) x W ) / 36 = total yardage needed

L is the width on the loom we calculated above, and H is dents per inch on your heddle and W is the warp length we calculated above. 

Since we will be weaving in plain weave I would buy or make sure you have the same amount of yarn/ thread for the weft as you do for the warp. You will most definitely have leftovers this way, but calculating the exact amount of weft can be tricky. Plus having extra allows you to do a small sample or have extra on hand for mistakes or broken threads. 


Example time!

I will be using an 8 dent heddle and want my final project to be 24 x 24 plus about 1/5 inches of fringe (so since fringe is under 4 inches we will ignore this bit till we take the piece off the loom.)

Solving for L:  24 ÷ 0.9 ÷ 0.9 = 29.629 (I will round this to 30 to make things easy.

Solving for W: 24 + 12 = 42

Solving for total yardage of warp= 30 x 8 x 42 ÷ 36 = 280

So for warp and weft together I need: 560 yards of yarn. 

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