Thursday 8 April 2021

How to calculate how many metres of sock yarn you’ve used

The Marathon Sock KAL is in full swing, and one of things you might be asking yourself is ‘how do I work out how much yarn I’ve used?’ Well I’m here to give you a hand!

You will need:

  • Scales
  • Your yarn details
  • Your finished socks

Step 1: Weigh your socks

The first step is to weigh your socks. To do this, you need a set of digital scales: kitchen scales work fine, or you can use jewellers scales (just make sure the upper limit on them is more than 100 g). Put the socks on the scales and record how many grams the socks weigh (if your scales usually measure in ounces, you’ll have to switch them to grams by pressing the ‘units’ button to switch them to grams).

Pair of handknitted socks on a set of digital scales

These socks weigh 78g.

Step 2: Work out how many metres there are in one gram of yarn

To work out how many metres there are per gram of yarn, you need to know how much yarn there is in one ball/skein of your yarn in both metres and grams. This information can be found on the yarn band: this yarn has 400m per 100g skein.

Close up of a handknitted sock and a ball band with details of the yarn used

If the yarn band only gives the length in yards, divide this number by 1.094 – metres are a little bit longer than yards, e.g. 437/1.094 = 399m

To calculate the number of metres per gram, divide the number of metres in the ball by the number of grams in the ball, e.g. 400m/100g = 4m per gram. Take a note of this number.

Step 3: Calculate how many metres you used

Once you know how much your socks weigh, and how many metres there are per gram, simply multiply the number of grams by the number of metres.

e.g. 78g x 4m per g = 312m

And there you have it – your socks used 312m of yarn!


What if my socks use more than one yarn?

Pair of stripey handknitted socks with contrast heels, cuffs and toes, next to two half used balls of wool

If you’re making socks using more than one yarn, you’ll have to do a bit of extra work before you start your project. Before you cast on, you need to weigh each of your yarns. I like to write my numbers down in a table like this (usually scribbled on the back of the ball band!):


Weight at start

Weight at end

Weight of yarn used










Notebook with a list of yarn weights, resting on a stripey sock

When you’ve finished knitting your socks, weigh how much of each yarn you have left. Take the smaller number from the larger number, this tells you how much yarn you used.

Once you know how much of each type of yarn you used in grams, you need to convert this to metres as before.


There are lots of numbers after the decimal point. Do I need them all?

No! I only measure how much yarn I use to the nearest metre, because it’s hard to measure much more accurately than that – you use a bit for weaving in ends, and for winding to the right point in the colour sequence, and that yarn doesn’t end up in your finished socks!

Now you’re ready to enter your socks into the Marathon Sock KAL! You can find the entry form here.

Want know more about the Marathon Sock KAL? The KAL runs from April 1st 2021 until we have turned 26 miles of sock yarn into socks. You can read all about it in this post!

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