Calculations to knit socks ➗ 🧦 Step-by-step formula

Get your calculator ready, beginner Sock Lover! In this new installment of our guide to learn how to knit socks, we’re going to do some math. If numbers aren’t your strong point, relax! We explain some easy and simple calculations to knit tailor-made socks. Put into practice the formula with your foot measurements and the result of your 10×10-cm gauge swatch we showed you in previous posts. 

Anna, a teacher at Katia Academy, is already calculating what to teach for the next Tips&Tricks 

💡 Speaking of numbers… Did you know that human feet contain around a quarter of all the bones in the body? In total, we have 26 bones in each foot, including the toes and ankle bones. 

Calculations for knitting socks

Before continuing, we want to note that there are many other resources for knitting socks, from size charts to online calculators. In this post, we focus on the basic calculations to knit socks from scratch or adapt a basic sock pattern to your taste: 

• Number of stitches needed to cover the width of the foot (X) 
• Number of stitches you need to cast on to knit socks: 
  • toe-up (∆) 
  • cuff-down (Z) 
• Number of rounds needed to cover the length of the foot (Y) 

📌 We encourage you to make your calculations for fun and out of curiosity! Keep in mind that you won’t always have to adapt all these numbers. Dare to knit with these numbers as a guide, without worrying about making a mistake. Remember 2 advantages: knitting is quite elastic, and you can also try on your socks as you go.

Step-by-step formula

After you’ve measured your foot and counted the number of stitches and rounds in 10×10 cm, repeat a simple cross-multiplication formula. 

Number of stitches needed to cover the width of the foot 

1. Multiply the number of stitches (in 10 cm from your swatch) by your foot’s circumference in centimeters. 

2. Then, divide the result of that multiplication by 10, which is the centimeters from the 10×10-cm gauge swatch.

➗ Example: How many stitches do you need to knit to cover a foot width circumference of 22 centimeters if your gauge swatch is 30 stitches in 10 centimeters? (22 cm x 30 stitches) / 10 cm = 66 stitches.

Number of stitches you need to cast on to knit toe-up socks 

3. Divide the number of stitches needed to cover the foot width circumference by 4. 

➗ Example: How many stitches should you cast on to knit toe-up socks? (22 cm x 30 stitches) / 10 cm = 66 stitches / 4 = 16.5 stitches (round down to 16) 

4. You should divide the result: 

• by 2 if you’re knitting on circular needles 

➗ Example: 16.5 stitches / 2 = 8.25 stitches (round down to 8) 

• by 4 if you knit on double-pointed needles, so you have the same number of stitches on each needle. 

➗ Example: 16.5 stitches / 4 = 4.125 stitches (round down to 4) 

📌 If the number of stitches you should cast on is an uneven number, round up or down to an even number. If you’re going to knit with double-pointed needles, try to make it a multiple of 4, to be able to evenly distribute the stitches across the needles. 

Number of stitches you need to cast on to knit cuff-down socks 

1. Multiply the number of stitches (in 10 cm from your swatch) by your leg circumference in centimeters (between your ankle and the beginning of your calf). 

2. Then, divide the result of that multiplication by 10, which is the centimeters from the 10×10-cm gauge swatch. 

➗ Example: If your leg diameter measures 25 centimeters and your gauge swatch is 30 stitches in 10 centimeters: (25 cm x 30 stitches) / 10 cm = 75 stitches 

📌 If you start your sock with some kind of ribbing, we recommend casting on a few stitches less. So round down to an even number when distributing the stitches across both circular needles, or to a multiple of 4 if you’re knitting on a set of double-pointed needles. 

➗ Examples 

• 75 stitches / 2 = 37.5 stitches (round down to 36 stitches per needle) 
• 75 stitches / 4 = 18.75 stitches (round down to 16 stitches per needle) 

Number of rounds needed to cover the length of the foot 

1. Multiply the number of rounds (in 10 cm from your swatch) by your foot length in centimeters. 

2. Then, divide the result of that multiplication by 10, which is the centimeters from the 10×10-cm gauge swatch. 

➗ Example: How many rounds do you need to knit to cover a foot length circumference of 25 centimeters if your gauge swatch is 40 rounds in 10 centimeters? (25 cm x 40 rounds) / 10 cm = 100 rounds (from toe to heel). 

Save this post in your favorites to keep it to hand for your future sock projects. 

Guide to learn how to knit socks 

Done! With these calculations, you have the most important numbers to start making your tailor-made socks. And if you’re asking yourself: “But… How do I cast on?” In the next post, we’ll show you some cast-ons. We’ll also tell you how to cast on two-at-a-time socks using the magic loop technique. 

In short, beginner Sock Lover, visit Katia’s blog every week because this guide to learn how to knit socks is made especially for you: 

• Sock yarns 🧦 How to choose the best yarn to knit socks with? 
• How to measure your foot 🧦 
• Gauge swatch in the round ➕ Steek technique 🧦 
• Calculations to knit socks ➗ 🧦 Step-by-step formula 
• How to cast on two-at-a-time socks 🧦 Seamless toe methods 
• How to knit a sock heel 🧦 Videos with step-by-step instructions 
• Sock project sheet 🧦 Free PDF 

That’s all for today, we look forward to reading your sock questions, suggestions, and experiences in the comments. 

Happy Socks, Katia Lover!