Calculating the Yarn - How to Warp a Loom

Calculate the Yarn Needed

Even if you have a pre-determined pattern, it is a good idea to double check that you have sufficient yarn to complete your project.

Take-up & Shrinkage

To calculate the length of warp required, take the length of your finished project and add 10% - 15% for take-up and shrinkage.

e.g. Finished project: Table Runner length = 36" + 2 inch hems = 40"
Take up & shrinkage 15% = 6"
Total length = 46"

Loom Waste

You will need additional warp length to be able to tie the warp ends to the back and front of the loom. This is called "loom waste". Loom waste is generally about 27" but I add a full yard for loom waste. This gives me a few additional inches of warp for sampling and playing with new designs or colors.

So, for this project you would need:
46" + loom waste 36" = Total 82" or 2.3 yards warp length.

Make More

Because there is always a considerable amount of loom waste in a weaving project, it is usually advisable to make more than 1 item at a time.
To make 2 table runners, the warp length would be:
2 x 46" = 92" + loom waste 36" = 128" or 3.5 yards.

Width of Project

Next, you will need to know the desired width of your project. Add 10% - 15% for take-up and shrinkage.
Project width: 17"
Takeup & shrinkage - 15%: 2.5"
Total width: 19.5"

EPI

You will now need to calculate how many ends of yarn you require. Using the sett that you figured out above, multiply the sett (number of ends per inch) times the total width of the project.

Sett: 20 epi
Total width: 19.5"
18 x 19.5" = 390 ends

Total Warp

Each warp end will be 3.5 yards long and you will need 390 ends. To calculate the total warp length, multiply the total warp length x the total number of ends.
warp length: 3.5 yards
# ends: 390
3.5 x 390 = 1365 yards

YPP

Yarn is usually sold by weight, in number of lbs. or grams. The yardage measurement is sometimes shown on the cone of yarn, or you can ask your yarn supplier how many yards per pound there are in the yarn you purchased. The hemp yarn shown above has 1500 yards per pound (ypp). So you would need 1365/1500 = .9 lb. of yarn for the warp.

Weft

Don't forget that you will need yarn to weave the weft as well. If you are using the same yarn for weft as well, you will need approx. the same amount to complete the two table runners - 1.8 lbs.

Part 5: Warping Board

Return to:

10 Steps to Warping

Part 1: The Project
Part 2: The Sett
Part 3: The Reed
Part 4: Calculate Yarn
Part 5: Warping Board
Part 6: Warp Chains
Part 7: Sley Reed
Part 8: Thread Heddles
Part 9: Wind Warp
Part 10: Tie Warp to Loom

Related Resources:

Table of Setts
An expanded list of setts for various yarns.

Calculating the Yarn - 10 Steps on How to Warp a Loom - All Fiber Arts