Guest Blogger: Spinning 101 – Measuring Handspun: WPI and Grist

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Layla’s back with another great blog post.  With the new spinning features coming to Ravelry, understanding these two measurements will put all us spinners ahead of the game!

WPI and Grist are the two most common ways of measuring handspun to determine the yarn weight. In this case, I mean “weight” as in laceweight, worsted, bulky, etc, not mass. This information is useful to know when making substitutions for millspun yarn, matching your handspun to patterns, or intentionally designing a yarn with a specific project in mind.

WPI is short of “wraps per inch” it is, in short, the number of times you can wrap your handspun around a 1 inch section of a ruler or other measuring tool.

WPI Gauge

Grist is the ratio of length to mass of a skein. Traditionally, this is Yards per Pound (ypp) but metric measurements can be done in Meters per Kilo, or even Meters per 100g.

First, let me state for the record: Both measurements can be useful, to varying degrees, but neither is a substitution for the dreaded swatch. If you are spinning for a particular project, I recommend spinning a sample of at least 20 yards, measure both WPI and Grist (details below) BEFORE setting the twist, then set the twist, measure both WPI and Grist as again, make your swatch, wash your swatch, then taking the swatch measurements to see if you like the results. Why take the measurements both before and after setting the twist? In this case, the measurements before setting the twist are more useful for comparing to your spinning project in progress, to make sure you are spinning consistently. The measurements after setting the twist are of completed yarn, and more useful for finial comparisons.


To correctly measure WPI, hold the yarn at a 90 degree angle to the tool, and then rotate the tool to wind the yarn on. Yes, it’d be easier, and quicker, to hold the tool still and wind the yarn around it in a big circle, but that would change the twist of the yarn, and so the measurement. So again: Hold the yarn in one place. Rotate the tool.

Just like when you measure a swatch, you don’t just count the number of stitches in one inch and call it done, you measure over 4 inches and divided it, so too, when measuring WPI, it’s best to measure over a longer length, then divide it out to get the WPI. Ideally, it’s also best, and more accurate, to measure several different locations in the skein and average those as well, given the consistency of handspun varies more than millspun. Have I even done this? Honestly, no. But in theory, it’d be better.

WPI is fairly subjective. Every spinner winds on a differently. Some loosely nest the yarn together, just so it’s touching, some pack it together a little, some pack it together until they can’t cram it together anymore. I’m not going to argue how tight you should pack it. Instead, let me suggest you just measure the WPI of millspun yarn at different weights, to use as control group. If you know *you* measure the WPI of millspun worsted weight yarn at 11 WPI, then it doesn’t matter at all if other people measure it at 12, or 9, or whatever. Just measure however you like, but do so consistently, and always use the same tool, if possible. Do not trust the suggested WPI of yarn in the Raverly database and pull down menu.


Grist is a less subjective measurement than WPI, but it can still vary a bit. The weight of yarn varies, depending on the humidity. On a humid day, your yarn will hold more water, and be heavier. On a dry day, your yarn will hold less water, and be lighter. When weighing your yarn, make sure the skein is dry, and ideally, an “averagely humid” day where you live. (For those curious: the standard for commercial yarns is to measure at 12%-15% humidity.)

Length can vary too. If you’ve ever wound a skein onto a niddy noddy or skein winder, set the twist, then tried to loop it back over the same tool, and found it was too tight to do so, you know this. Since your yarn is held under tension when being spun and plied, it is usual for it to relax, and shorten, once the twist is set. To accurately measure the length of your handspun, you should measure the length *after* the twist has been set.

For those using the metric system, figuring meters per kilo is pretty straightforward.

For those of us stuck using the Imperial system, or a combination, calculating grist can be a bit more…mathy. Since it is common to measure skein length in yards, but weight in grams, allow me to give you the following formula:

_____yards / _____grams * 453.592 = ____ypp

And finally, a word about directly comparing the grist of millspun yarn to handspun: It is common for handspun yarn to be denser than millspun. It depends on the drafting technique, as well as the spinner. It could vary as much as 20%. *Grist is excellent* for comparing your own handspun to your own handspun; for example, to make sure your skeins are consistent when spinning for a big project, like a sweater. But if you want to compare millspun to handspun, I recommend stitches per inch when swatched, and if you don’t want to bother with that, WPI.

Ravelry’s new spinning features, currently in beta, include fields to enter both WPI and Grist for handspun projects. To try it yourself, go to and enter the code: TDF. For more information on the new spinning features, check out the “Spinning Features on Ravelry” thread sticked in the Tour de Fleece forum, particularly Casey’s posts.


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