May 1

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Calculating yarn on hand

By janet

May 1, 2020


As I mentioned in my first post in this series, several mystery yarns have taken up residency in my stash. They’re not like the yarns I usually use, and not like the yarns I stockpiled in years past and have subsequently ignored. There’s just a ball of this or a spool of that: enough to do something with, but what?

In order to use yarns like these, you need to determine two things: what they are, and how much you have. I’ll cover calculating how many yards or meters of a yarn you’ve got available in this blog post; my next post will look at determining fibre content.

How much ya got?

First things first: you need to weigh your yarn, which means you need a scale. It should be precise enough to measure in grams or tenths of an ounce. I almost always use grams because they’re more precise.

If you’ve got enough empty cones and spools and similar to tare your scale before weighing the yarn, great. You can skip right to weighing the yarn itself minus the packaging. If you don’t have the empties or don’t know what I mean by taring, then do this instead:

First, weigh all the yarn, right on its cones, spools, or other packaging and make a note of the total. This is the weight of yarn+packaging, but we need to figure out the weight of only the yarn. If you’ve got more than one package of the yarn, you can weigh it all together.

To account for the packaging that the yarn is on – the cone, the cardboard spool, the bobbins, etc. – you need to figure out how much it weighs. If you have an empty one, you can weigh it.

If not, here’s a table of some common packaging that I had laying around the house:

Packaging Grams Ounces
UKI plastic cone, 7” 25 0.88
UKI plastic cone, 4.5” 12 0.42
Brassard cardboard spool, 4.25” 13 0.46
Brassard cardboard spool, 6.5” 16 0.56
Brassard plastic bobbin, 4” 6 0.21
Schacht plastic bobbin, 3.75” 6 0.21
Schacht plastic bobbin, 6” 9 0.32
Schacht wooden pirn, 6.25” 16 0.56
Black plastic pirn, 8” 31 1.09
Cardboard cone, 2.75” x 7” 24 0.85
Red plastic pirn, 6.25” 21 0.74
cone winder cone, 2” x 4” 16 0.56

If you’re not sure which of these your yarn is on, the safest bet is to pick the heaviest one it might be. That may lead to underestimating the amount of yarn you’ve got, sure, but that’s safer than overestimating. (Obviously there’s some variation: that green tape on my scale tells me that the small cardboard spools are 9g, but the two I just weighed came to 22 together, and the one I weighed when making the table above was 13.)

Now add up the weights of all the packages that were part of the original group you weighed, and then subtract that from the total weight of yarn+packaging. The difference is the weight of just the yarn itself, which is what we need.

In my case, 246g – 22g = 224g of yarn, not including the cardboard cores.

Determining YPP or MPG

The next piece of the puzzle is to figure out how many yards per pound (YPP) or meters per gram (MPG) your yarn has. If you know what your yarn is, this might be as easy as looking it up in the Handwoven Magazine Master Yarn Chart or searching for it online.

Look how helpful Google is in this situation!

If you don’t know what your yarn is (or don’t have access to the interwebs), all is not lost! If you’re lucky enough to have a [McMorran] Yarn Balance, the calculation is fairly simple. If you don’t, or if you don’t want to sacrifice even a yard or two of an extremely limited supply of mystery yarn, there’s another way that takes a little more effort but doesn’t necessarily “waste” the yarn being measured.

Using a Yarn Balance

Yarn balances (formerly called “McMorran balances” but no longer – perhaps someone else bought the rights?) come in two flavours: imperial (pounds and ounces) and metric (grams and kilograms). They both work the same way, and you can tell them apart because the balance arm on the metric ones aren’t clear. (I think they’re usually blue. Do they come in other colours? I don’t know!)

A yarn balance has three parts: a lid, the tower body, and the balance arm. The lid’s only function is to protect the arm when stored, so take it off and put it aside. Next put the tower body right at the edge of a table and set the metal axle pins of the balance arm into the shallow divots on the top of the tower body. This will position the plastic balance arm itself over the deeper grooves on the other two sides. The end of the arm with the notch will rise and the solid end will fall because it’s heavier. Make sure that the notch itself is on the top edge of the balance arm and that that arm is hanging beyond the edge of the table, like so:

Turns out it’s hard to see something clear without something bright behind it.

Now take a yard or so of your mystery yarn and fold it in half. Hang it by that fold from the notch in the balance arm – you can even make the fold into a larks head and put that right on the balance arm so that it can’t slide off easily. Chances are the notched end will crash right down to the bottom of its groove as soon as you let go of the yarn. If it doesn’t, you need more yarn. Add another length to the first so that both are hanging together from the arm. Keep adding until the arm drops.

Now the fun begins. The balance will be the most accurate if the two ends of the yarn hanging from the arm are close to the same length, so get yourself a pair of sharp scissors, take those two ends in hand, and start snipping! Be sure to let go of the yarn between snips to see what the balance arm does. ( If the solid end of the arm drops to the bottom of its groove, you’ve gone too far: measure out a new bit of yarn the length of your current one plus a few inches, and hang it on the arm in place of the original.)

Work in small snips until the arm begins to lift and then work in tiny snips. I usually work in centimeters (quarter inches) until the arm stop coming down emphatically when I let go. When the arm begins to lift you’ve got to go very carefully. At this point, I start snipping by half centimeters and pretty soon by tiny wee snips of a mm or 1/16” or so. The goal is to get the arm perfectly horizontal; it’s pretty important that you get as close as possible.

snipSNIPsnIPSnipSNIPSNIPsnip

Once the arm is as level as you can get it, take the yarn off and measure it – in inches if you’ve got an imperial balance, and in centimeters if you’ve got a metric one. If you have an imperial balance, multiply the number of inches (or fractions thereof) by 100. That’s the number of yards per pound your yarn has.

For instance: my bit of yarn was 27.25″ long. 27.25 x 100 = 2725 yards per pound, or about half way between an 8/2 cotton (3360 YPP) and an 5/2 (2100), which makes sense given the grist of the yarn. (To know how many yards per ounce, divide the yards per pound by 16: 840 ÷ 16 = 52.5 yards per ounce.)

If you have a metric balance, divide the number of centimeters (or fractions thereof) by 10. That’s the number of meters per gram your yarn has. For instance: if the yarn is 69.2 cm long, 69.2 / 10 = 6.2 meters per gram. (If you prefer to know meters per kilogram, multiply the length in centimeters by 100 instead: 69.2 cm * 100 = 6920 m/kg).

NB: If your yarn is thick and thin, it’s possible that you’re measuring a particularly thick or particularly thin bit, which will skew your results. It’s a good idea to go through the process a few times and then average all the results together.

Hey, look! I MADE YOU A CALCULATOR!

But what if you haven’t got a yarn balance?

The yarn balance simplifies the calculation by having a little arm that’s precisely calibrated to measure a reasonably short length of yarn, but it isn’t the only way to get to the goal. Another way is to weigh a known length of yarn and run the same kind of calculation. A short length is bound to be too light for most scales to weigh accurately, so the best approach is to wind yourself a tiny little “warp” and weigh that and the easiest way to do that is right on your warping board.

The first thing to do is to measure the length of your tiny warp: tie some other yarn onto the board, just as if you were putting on a guide string to wind a short little warp. Be sure to use knots rather than wrapping either end around a peg a bunch of times to secure it – you need to know exactly how far apart the two ends are. It doesn’t really matter how long this “warp” is so don’t worry about making it any particular length, just pick a path that’ll be quick and easy to follow. My intuition tells me that making your “warp” at least a yard long will introduce less error than something shorter, so I went with two passes on my warping board: from the cross to the opposite side, and then back to another point on the starting side. Leave that measuring string where it is for the time being.

Now use your mystery yarn to follow this path several times, until the whole lot looks like something your scale will be able to measure. I went there and back on my warping board five times, for a total of 10 ends. Tie off onto the last peg and count the number of ends you’ve got before doing anything else. Don’t tie the cross or the choke or anything else – you don’t want to add any weight at all. Now, being careful not to include the measuring string, chain your wee little warp off the board. I tied my chain into a knot at both ends – that didn’t add any extra yarn to the chain but still secured it so it can’t come apart. If you plan to unwind this wee chain so you can recover the yarn, you might want to skip that part. Just don’t add any other yarn to the chain because that will also add weight.

The next jobs are to measure the guide string and to weigh the tiny warp chain. Be sure to measure the guide string from the end of one loop to the end of the other loop. Use inches and ounces if you’re heading for yards per pound, and centimeters and grams if you’re aiming for meters per kilogram. Then either math them this way for imperial…

… or like this for metric.

I MADE YOU A CALCULATOR FOR THIS, TOO! Still leaving the bits above though so you can see just how the math is mathing.

This brings you to the same point the yarn balance did: the number of yards per pound or meters per gram in your mystery yarn.

“Tell me what I’ve got, what I’ve really really got”

Now that you’ve determined the yards per pound or meters per gram of your mystery yarn, you can calculate how much of it you’ve actually got. Like this…

…or like this, depending on your units.

GUESS WHAT? Okay, not a big surprise by now. Here’s the calculator:

And there you have it: the number of yards or meters of your mystery yarn you’ve actually got available to work with. Huzzah!

Well… approximately, anyway.

When testing my yarn balance against yarns of known yards/lb, I didn’t get exactly the right answers. When I tested 8/2 cotton, twice in a row with two different spools my cut length measured 35.5” long, which tells me the yarn is 3550 yards/lb, or 5.6% more yards per pound than its listed 3360 ypp. When I measured 8/4 cotton, my bit of yarn was 17.125”, or 1712.5 yards/lb, or 1.9% more than the 1680 ypp it’s supposed to be. Without actually measuring all the yarn on the spools, there’s no telling whether the yarn balance is right or wrong – it’s possible that my spools of yarn are slightly thinner than the standard, or that the balance arm is ever so slightly misaligned. It’s also really humid in my house, which increases the weight of yarn (the standard ypp are calculated at 21.1 C/70 F and 65% humidity). Regardless, 5% isn’t too big a margin of error. I’ll just remember to take 5% off any calculations I make with the balance for safety’s sake.

In theory, measuring the weight and length of a mini “warp” should be even more accurate than a yarn balance since you’re working with larger pieces of yarn. In practice, that’s going to depend again on how careful you are, how precise and how accurate your scale and measuring equipment are, the temp and humidity in your house, etc. When I used this method to measure 3/2 mercerized cotton, for instance, I got 1132 ypp, whereas the listed ypp for it is 1200. That’s still just about 5% off.

The quality of your tools is also a fact. My postal scale can only measure tenths of an ounce, which isn’t really precise enough for these calculations – that’s part of the reason I always work in grams.

I still plan to assume a 5% margin of error to be on the safe side. Worst case scenario, I’ll have a little yarn left over to fix broken warp ends or make repairs if necessary.

FYI: armed with either this yards/lb or m/kg info, you might well be able to figure out exactly what your mystery yarn is by hunting through the Handwoven Master Yarn Chart for something that has a similar value. Lots of yarns could be the same ypp, though, so the next thing you ought to do is determine the fibre content of your yarn. Which is coming next!

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  1. This is a wonderful explanation! I recently acquired a yarn balance from a guild member who was moving and had not a clue how to use it! Yeah, now I know!
    Thanks so much!

  2. Janet thank you very much for this interesting piece! I usually measure out a couple of lengths and weigh it on my jewellery scale and do the calcs, but the tiny warp is the way I’ll go from here on! I’m not sure I’d have the patience for the balance scale‍♀️

  3. Janet,
    I found this very helpful, albeit I don’t have many mystery yarns in my stash, but some. I was wondering if the difference you mentioned could be from a) the type of dye used, b) they were wound using metrics but used a chart of yds/lb for marketing, c) wherever it was wound had a different climate and they were wound on cardboard cones that absorb a lot of moisture in a damp climate.

  4. This was a very useful read. I hate figuring warp and usually just eyeball it all even when winding very precise narrow stripes and plaids. I have not woven in several years and took this course just to practice the stuff I have previously avoided. Your nifty little calculators make the math much easier. Most of my stash is colorful cottons & wools on large unmarked cones so I am still doing a lot of peering at the Master Yarn Chart for good clues and guesstimating. Thanks.

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