“How to…” calculate the length of your foundation chain

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In this post i’m going to tell you how to work out the length of your foundation chain for your next project. For a tutorial on how to make a foundation chain, click here or watch the video below.

The foundation chain forms the basis of many crochet blankets and will determine how wide your final project is.

The number of chains in your foundation chain is determined by a few different factors:

1. Stitch Type:
• This can be a ripple stitch, chevron or just a simple treble. This is important because in the example of a ripple, every ripple contains 14 chains, whereas for a simple treble, it is just 1-to-1 of trebles to chains.
2. Number of repeats:
• After choosing your stitch type, you then need to decide how many times you want to repeat this in your blanket. In the case of a ripple (which needs 14 chains per ripple) you will probably want to have fewer repeats than for a simple treble blanket which only has 1 chain per treble.
3. Chains in first stitch:
• After making your foundation chain you’ll start your blanket from row 1. The first stitch of row 1 is always made up of chains from your foundation chain – this will make more sense when we start making our blankets. What this means is we also need to add in extra chains to our foundation chain to account for this first stitch of row 1.

All good patterns should tell you how many chains you will need for the stitch type and also the first stitch of row 1. This will allow you to make your blanket is a big or small as you wish.

When it comes to calculating the total number of chains for your foundation chain, you can use the following formula:

In the case of our ripple blanket which has 14 chains per ripple and 3 chains for our first stitch in row 1, we would have the following formula:

All you would then need to decide is how many times you want to repeat the ripple pattern.

How many chains do I need for a given width?

Now what about if you wanted to make a blanket of a set width?

In this case, not only do we need to consider our stitch type, number of repeats and chains in first stitch as before but we must also factor in the weight of our yarn and the hook size we’re using:

1. Yarn Weight:
• Yarns come in various different weights – the higher the weight, the thicker the yarn and the larger your stitches will be.
2. Hook Size:
• Similarly to the yarn, a larger hook = larger stitches.

To start with, we would need to ake a small practice piece using our chosen yarn and hook. We can then measure the height and width of this piece to work out the height and width of our stitches.

For example, If I make a practice piece, also known as a swatch, I can measure the height and width of this piece and divide by each dimension by the corresponding number of stitches. This would then tell me the size of each individual stitch.

For example in the images below, I’ve made a 10cm x 10cm treble crochet square. The square is 14 stitches across and 8 stitches high.

If I wanted a final blanket that was 50cm wide, I would do the following calculation.

Firstly, to find the width of one stitch:

Then to find the number of stitches in 50cm:

And so for a blanket that’s 50cm wide, we would need 70 chains in our foundation row.

As always, if there’s another tutorial you’d like to see, let me know in the comments!

In the meantime, happy crocheting!

Sophie