Yarn Calculator for Weavers
My first weaving project was a set of dishtowels in 8/2 cotton. I had a pattern, I had yarn, and I was confident I'd calculated everything correctly. I consulted three different resources for my EPI. I got three different answers. I picked the middle one and hoped for the best.
I forgot to account for draw-in. I left no room for sampling. And I underbought my weft yarn - not by a little, but by enough that I ran out mid-project and had to reorder. This was during COVID. I waited six weeks for yarn. My loom sat idle.
Not a weaving problem. A planning problem…
That's why I built the Weavers Weft Yarn Calculator.
Five inputs.
All the math done for you.
Exactly how much yarn you need.
How to Use The Calculator (in 3 easy steps)
Step 1: five dropdown menus. Pick your options - the calculator handles the rest.
Project type - your project selection pre-fills your finished dimensions as a starting point
Yarn - the calculator knows the yardage per tube or cone for each yarn we carry
Weave structure - sets your EPI, PPI, draw-in, and take-up defaults
Loom type - pre-fills your loom waste in Step 2
Items on warp - how many towels, placemats, scarves, or whatever you're making in one warp
Step 2 does all the calculations for you - finished dimensions, EPI, PPI, draw-in, take-up, shrinkage, loom waste, hem allowance. Every field is editable if your pattern calls for something different. Overridden fields turn red so you can track what you've changed.
Step 3 (optional): Break it down by color. Enter each color and its percentage of the warp or weft. The calculator combines matching colors across warp and weft automatically - one accurate tube count per color, no doubling up."
Then the calculator hands you your answer - total warp yardage, total weft yardage, and exactly how much yarn to buy. No math required.
When you're done, one click gives you a clean printable summary to tuck into your weaving notebook. And if any of the terms are new to you, there's a plain-language glossary of 12 weaving terms right at the bottom - no dictionary required.
What the Calculator Does (so you don’t have to…)
The calculator accounts for things that are easy to forget - or you never knew were needed:
Loom waste - the warp you wind on but can't weave - from the back beam to the front of the heddles
Draw-in - the natural narrowing of your fabric width as you weave
Take-up - the extra weft yarn consumed as the threads travel over and under the warp
Shrinkage - the reduction in length and width when your finished cloth is washed and the threads relax
These aren't complicated concepts, but if you skip them, your estimate will be off. The calculator has them built in as defaults - sensible starting points based on your yarn and weave structure - so you don't have to look them up each time.
Try It - with the Blog 2 Dishtowel Project
If you're working through the Playing with Stripes pattern from Blog 2, the calculator is set up perfectly for it. Select Dishtowel, Maurice Brassard 8/2 Cotton, Plain Weave, your loom type, and 6 items on warp. The calculator will auto-fill 20" × 30" - update the finished dimensions in Step 2 to 15" wide × 28" long if you want to match the pattern. You'll know exactly what to order before you place a single yarn purchase.
One More Thing
The calculator is new and I want to make sure it's working well for real weavers with real projects. If something feels off, is missing, or could be clearer - there's a short feedback form at the bottom of the calculator. I read every submission and respond personally. Your input is how this tool gets better.
The calculator is free. Always will be.
Check it out (link below).
As always, Happy Weaving!
