How much yarn do I need for my crochet project?

Worked example

Let’s say we have a swatch of half double crochet 30 stitches wide by 24 rows long which measures 15cm by 15cm. It uses double knit yarn which comes in 100g balls. Each ball has approximately 250m of yarn.

We want to make a scarf that measures 150cm long and 25cm wide.

Step 1. You weigh your sample

It weighs 20g

You have 20g in your swatch, so you multiply that my the metres per from from step 2:

20 * 2.5 = 50m of yarn in your swatch

Step 4. Work out the area of your swatch

Your swatch measures 15cm long and wide:

15 * 15 = 225cm squared

Step 5. Work out how many meters you need per cm squared of area

Divide the total metres used (Step 3) by the number of cm squared in your swatch (Step 4):

50 / 225 = 0.22222

Step 6. Work out the size of your finished project

If it’s a garment, you may need to work out the size of each panel, or use the body measurements to make an estimate. Likewise if it’s a hat or something similar, you will need to make some judgement calls (if you know the design, you may prefer to use the stitch count method below)

In our example, we are making a scarf which is 25cm wide by 150cm long, so we can work out the total area of the finished item by multiplying the two numbers together:

150 * 25 = 3750cm squared

Step 7. Work out the total number of metres needed for your project

To do this, we will multiply the total number of cm squared by the number of metres for every 1cm squared (the number we calculated in Step 5)

3750 * 0.2222 = 833.33m

So you now know you will need a total of 834m of yarn for your scarf

Step 8. Calculate the number of balls needed (optional)

You know that each ball of yarn has 250m so you’re going to divide the total number of metres by the number in each ball

662 / 250 = 3.34 balls

You’ll need to round that up to the the nearest whole number (always round up).

So if you’re yarn shopping you’ll need to buy 4 balls for this scarf!

Using stitch counts to calculate yet quantities

This uses a very similar method to using area but instead of calculating your cm square, you calculate stitch count per metre.

Again I have outlined the steps and followed up using the same worked example (let’s see if I get the same result!). Steps 1-3 are the same as the previous method.

Step by step instructions for stitch count calculations

• Step 1: Take your sample and weigh it – write down the weight
• Step 2: Use the information on your ball band to calculate how many meters per gram (m/g) you get from your yarn: meters per ball divided by ball weight – write it down
• Step 3: Work out how many metres you have used in your swatch; m/g measurement (Step 2) times weight of swatch (Step 1) – write it down
• Step 4: Calculate the number of stitches in your sample; number of rows multiplied by the number of stitches in each row – write it down
• Step 5: Work out the number stitches your stitch pattern uses per metre; divide the number of stitches used in the sample (Step 4) by the number of metres in your sample (Step 3) – write it down
• Step 6: Calculate the total number of stitches you’ll need in your final project. To do this, you’ll need to know the height and width of each stitch and the desired length and width of your final piece;
  • Take the height and width of the sample and divide it by the number of rows and stitches in the sample respectively to get the stitch height and width->
  • Divide the desired final length of the piece by the row height to get the number of rows needed ->
  • Divide the desired final width of the piece by the width of each stitch to get the number of stitches across ->
  • Multiply the total number of rows by the number of stitches in each row to get the total number of stitches in your finished piece – write that down
• Step 7: Work out how many meters you’ll need for the size of your finished project; total number of stitches (Step 6) divided by stitches per metre (Step 5) which will give you the total number of metres of yarn needed for your project
• Step 8: Work out how many balls that is (divide the total meterage by the number of meters in each ball (from the ball band) and round up)

Worked example using stitch counts

We’ll use the same example with swatch of half double crochet 30 sts wide by 24 rows long, measuring 15cm by 15cm, it uses double knit yarn which comes in 100g balls, each ball has approximately 250m of yarn.

This swatch would have a gauge measurement of 20 sts and 16 rows in 10cm. You could use this to work out that a 150cm by 25cm scarf would need 240 rows and 50 sts in each row – You will need this calculation for Step 6. You can read this post to learn how to use gauge to calculate your stitch and row counts but I’ve broken it down in a slightly different way in example below (the results are the same).

Step 1. You weigh your sample

It weighs 20g

Step 2. Work out how many metres per gram you get from your yarn

To do this, you divide the total meters in each ball by the number of grams:

250m / 100g = 2.5m/g

So 1 gram of yarn measures 2.5metres long

Step 3. Work out how many meters you used in your swatch

You have 20g in your swatch, so you multiply that my the metres per from from step 2:

20 * 2.5 = 50m of yarn in your swatch

Step 4. Work out the number of stitches used in your sample

Your sample has 24 rows with 30 sts in each row:

24 * 30 = 720 sts

Step 5. Calculate how many stitches per metre your stitch pattern uses

You’ll divide the total number of sts by the total number of metres in your sample to find this out:

720 / 50 = 14.4 sts per metre

Note that it doesn’t matter if your stitch pattern uses different types of stitches. So long as your swatch is a representative example of the pattern, this is an average of all the sts.

Step 6. Calculate how many stitches your final project will need

• Height of each stitch: 15cm / 24 rows = 0.625cm per row (each st is 0.625cm tall)
• Width of each stitch: 15cm/30 stitches = 0.5cm per stitch (each stitch is half a cm wide)
• Number of rows in finished scarf = length/height of row; 150/0.625 = 240 rows
• Number of stitches in each row = width/width of stitch; 25/0.5= 50 stitches per row

Your final project will need 240 rows, each with 50 sts: 240 * 50 = 12,000 sts

Step 7. Work out the total number of metres needed for your project

So here we will take the total number of sts and divide it by the number of sts per metre to get the total number of metres:

12,000 / 14.4 = 833.33m

So you now know you will need 834m in total for your scarf – that’s exactly the same number we got when using area!!! (I love it when a plan comes together!)

Step 8. How many balls of yarn is this?

You know that each ball of yarn has 250m so you’re going to divide the total number of metres by the number in each ball

834 / 240 = 3.34 balls

You’ll still need 4 balls of yarn!