You have found the pattern, but not the yarn. Maybe it is sold out, maybe you want a different colour, or you have a yarn at home that you would rather use. Swapping is fine. What decides whether the garment turns out as it should is whether you match the gauge.
Gauge is how many stitches and rounds you get over 10 cm. Every measurement in a pattern is worked out from it. If you are off by one stitch per 10 cm, a sweater can easily end up 8–10 cm too wide or too tight.
Look at more than the thickness
Two yarns can have the same recommended needle size and still give completely different garments. Before you buy, compare these three on the ball band:
| What you look at | Why it matters |
|---|---|
| Yardage (metres per 50 g) | Tells you most about the thickness. If the new yarn is within 10 % of the old one, you are on safe ground. |
| Fibre | Wool, alpaca, cotton and mohair drape differently. Alpaca and cotton are heavier and stretch more in length than wool. |
| Number of strands in the pattern | If it says two strands held together, you must compare with both strands combined. |
The recommended needle size on the ball band is only a starting point. The gauge swatch is what decides.
Knit a gauge swatch and measure it
A gauge swatch takes an evening and saves you from a sweater that does not fit. Here is how:
- Cast on enough stitches for 15 cm width. With a gauge of 12 stitches over 10 cm, that is 18 stitches.
- Knit in the stitch pattern the pattern gives for the gauge, usually stocking stitch. Knit until the swatch is 15 cm high.
- Cast off loosely. Treat the swatch the way you will treat the garment, so it can settle.
- Lay the swatch flat without stretching it. Place two pins 10 cm apart in the middle of the swatch, away from the edges.
- Count the stitches between the pins. Do the same vertically for the rows.
If the garment is knitted in the round, you can knit the gauge swatch in the round too. Many people knit a little looser than they purl, so a swatch knitted back and forth can give a different number.
When the number is off: change needles
If you do not match the gauge, it is the needle you adjust, not the stitch count in the pattern.
- Too many stitches over 10 cm: you knit tighter than the pattern. Go up one needle size.
- Too few stitches over 10 cm: you knit looser. Go down one needle size.
Knit a new swatch after each needle change. Put the stitches across the width first. You can usually adjust the rounds by knitting to a measurement instead of a number of rounds.
The gauge calculator shows whether you need a different needle when you enter the stitches from your gauge swatch.
If you have to go more than two needle sizes up or down, the yarn is too thick or too thin for the pattern. The garment will then be stiff or loose and open even if the numbers match, and it is better to choose a different yarn.
Mohair and two strands held together
In many of my patterns, mohair is held together with another strand. The mohair gives the glow and the soft drape, the other strand gives weight and shape. If you swap out one of them, you change both.
If you want to knit with one strand instead of two, find a yarn with roughly the same combined thickness. Work out the yardage for two strands like this:
1 / L = 1 / L₁ + 1 / L₂
L₁ and L₂ are metres per 50 g for each strand. Example: mohair with 225 m and wool with 100 m per 50 g gives roughly 69 m per 50 g held together. That is the number the new yarn should be close to.
You get the gauge, but not necessarily the same surface. A smooth single strand gives clearer stitch definition than mohair, and the garment hangs closer to the body. Knit the gauge swatch and feel it before you decide.
Work out how much yarn you need
Count in metres, not in grams. Two yarns with the same weight can have very different lengths.
- Multiply the number of balls in the pattern by the yardage of the yarn in the pattern. That gives you the total metres.
- Divide by the yardage of the new yarn.
- Round up to a whole ball.
Example: the pattern uses 8 balls of 100 m, so 800 m. The new yarn has 125 m per ball. 800 divided by 125 is 6.4, so you buy 7 balls.
The yarn calculator does the sum for you.
Buy all the balls from the same dye lot. Colours can vary a little from dye lot to dye lot, and it shows in a finished garment.
A different yarn gives a new garment
When you swap yarn, you make your own version. The colour, the drape and the surface become yours. As long as the gauge matches, the measurements will be the same as in the pattern.
You do not need to calculate by hand. In the calculators in Knittipedia you type in the numbers from your gauge swatch and the ball band, and the page works out the rest. Feel free to share your version with #cosymonday.
Good luck <3
Anne-Turid