How to calculate a knitting pattern – the magic math (Part IV of Knitting Pattern Design)

This Blog is Part IV of the Blog serie about Knitting Pattern Design.

After we speak about how to make the perfect swatch for the right gauge for Knitting Pattern Design in Part III, we are going to speak about how to calculate stitch number, rows and do the magic math!

After we took the measurements and wrote them down in a table or on the sketch, together with the row and stitch number of the 10cm/4″ Swatch, we are ready to calculate the exact stitch & row numbers of the garment.

Not always we wanna write the row number down for a pattern. Many times it is enough to give the hight in cm/inch (for example “repeat row 1& 2 until garment measures x cm/inch”). Anyway it can’t harm to have all the row and stitch numbers ready before you go to the actual writing part.

The math we gonna use, is very simple. Basically you learned it in grammar school, it is the rule of three.

It is helpful to calculate the stitch and row number down to 1 cm or 1″:

Example for a sweater:

Your swatch 10 cm x 10 cm is equal to 27 stitches and 37 rows.
1 cm x 1 cm is equal to 2.7 stitches and 3.7 rows.

The edge you want to cast on measures 40 cm, so simply:
2.7 stitches x 40 = 108 stitches

For waist, sleeve,
 neck … shaping:
You know you want to decrease a total of 3 cm width within 13 cm high.
3 cm x 2.7 stitches = 8.1 -> 8 stitches
13 cm x 3.7 rows = 48.1 -> 48 rows
Distribute evenly the stitches you want to decrease in the rows:
48 / 8 = 6 -> you decrease every 6 row one stitch on both sides.

INCREASES you calculate in the same manner as the decreases.

You calculate basically the same as you did for the decreases and increases. But for a round neck, for example, you also bind off stitches and the decreases are not always evenly distributed. First you decrease more stitches in less rows for a flat shape, then you decrease less stitches in more rows for a steep shape.

The different techniques of fitting sleeves and how to calculate will need some other Blogs 🙂

All squared items like blankets, simple mittens or scarves are more easy to calculate. This will be a good start if this is new to you.

Calculate all stitch and row numbers for all the measurements you took. Like this you are prepared for knitting your sample.

While making your sample, stay open minded for any changes on the pattern and check every now and then if your calculations really lead to the desired shape.

Enjoy knitting 😉

Thank you for reading and have a nice weekend!




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