What is the formula?

Hello everyone.

I’ve just started Knitting about a month ago and I’ve made a few scarves with different patterns and colors and what not.

My question today is that I’m tiring to figure out what the formula is for how many stitches I need to cast on for various projects.

For example; if I wanted to make an armband and the arm measured 22 inches at the middle of the bicep, my circular needles are number 8 (us) and 24 inches long. How do I use this information to tell me I need (blank) number of stitches to cast on?

Also I’ve notice that in the books that I have they all want me to make a swatch and them measure it out and blah, blah, blah,. I’m thinking there must be some formula or something

If I just wanted to make a hat and My head measured 22 inches as well I’m figuring that making a swatch would not help me because I’m decreasing and what not, then if I’m doing ribbing then that’s a whole other issue.

Long story short I don’t want to waste my yarn making swatches and I have a lot of ideas that are not from patterns. I’m sure this is something that is obviously a beginner thing that I’m going through so if someone could help me I would be ever so grateful


First off, swatching doesn’t have to waste yarn. You can reuse it.

What you’re trying to determine is gauge–the number of stitches per inch. If you want to make something 22 inches around, and your gauge is 4 stitches per inch, you’d cast on 88 stitches. You can’t know your gauge unless you knit with the needles and yarn you intend to use.

If you’re making up a pattern, then you find your gauge and work from there. If your following a pattern, you adjust your needle size to get the gauge that’s called for in the pattern so your’s will turn out the same size.

As for circular needles, your needle can’t be longer than the circumference of the item you want to knit. Shorter, yes, since the stitches can be scrunched together. If the needle is too long, the stitches won’t fit around. Your 24" needle won’t work for a 22" piece, but a 16" needle would. You also have to allow for a certain amount of stretch, since all knitting is stretchy.

thank you this does help out. I figured there must be a way. I mean there were times when not everyone could go look on-line( or a book for that matter) and find a pattern for a sweater and adjust from there.

So what your saying is that the formula that I want involves that swatch. (sigh) ok this does explain why my hats were way too big.

but then this poses another question

if im knitting the sweater and my chest measures 52 inches around, would i be able to use thoes 24 in needles or would I need some a little longer

(like I said I’m very new to this)

I would say it depends on how you knit it, if you’re knitting flat, then, it makes little difference. If you’re knitting it in the round, a longer cable might suit you better.

For the sweater, you could use 24" needles even for knitting in the round, but if your yarn is thicker, it might be easier to use 36".

theoretically you could use a 24" circular needle for somthing 52" but the sitches would be very bunched up and could make it difficlt to handle or see what you were doing. somting of that size would be better off with a needle in the 36"+ range to help disperse he stitches and weight better.

I hate swatching. and i am tight with my budget and there for yarn, but am learning that it is best to do a decent size swatch which i can then unravel and reuse the yarn. When you do the swatch make sure you do it in the stitch pattern you intend to use for the finished piece (i.e. ribbing, stockinette etc) as the different tensions can give you very different fits.

Sometimes the pattern will say the gauge is in stockinette even though the st pattern may not be. The reasoning behind this is if you match the gaugein St st, you will be close enough in whatever stitch pattern it is.