Q&A: How Much Yarn Do I Need?

The quintessential question for all who knit and crochet! It should surprise none of you that the answer is usually, "it depends..." - and it always involves math.

I HAVE A PATTERN

• Congratulations! This is the easiest route to an answer! Then it comes down to the size you make and the yarn you choose.
• It's always worth a minute to look on Ravelry and the designer's website to see if there are pattern errata before you start.
• Want to use something other than the recommended yarn? We have an entire post on that to help...

I HAVE NO PATTERN BUT JUST WANT TO MAKE SOCKS OR A HAT

• For both knit and crochet, the general rule of thumb is that a typical 100g skein of yarn will safely make you a hat. Crochet takes about 25% more yarn than knitting (though it depends a lot on the stitches used!). So if you knit it, you will have more left over than if you crochet.
• For knitting, the general rule of thumb for socks is that a typical 100g skein of fingering yarn will get you a pair of average women's socks for an average foot. Very tight gauge, complicated cables, men's, large woman's size, or knee-highs? Buy 2 skeins.

I HAVE NO PATTERN AND AM MAKING A SCARF/BLANKET/SQUARE WRAP

• You can calculate a very rough yarn estimate for rectangular, stockinette or garter stitch items with this handy formula. It works best in the middle of the yarn size spectrum and can falter at the extremes like lace and super bulky. It also doesn't account for cables or lace or other textured stitch patterning.
• Formula: (length x width x gauge) / 6 = yards needed. Length and width are in inches and gauge is in stitches per inch. The division by 6 is to convert the answer from square inches to yards. 
• For example, if you'd like a scarf 48" long and 8" wide using a worsted weight yarn, (48 x 8 x 5) / 6 = 320 yards.
• Round up as running out of yarn is the worst!

I HAVE NO PATTERN AND AM MAKING A SWEATER/VEST/ETC

• From here on out, we suggest the KnitBot Stashbot by Hannah Fettig. This incredibly useful little booklet is a godsend for knitters trying to figure out basic amounts for basic projects. Sadly, we have no such guide for crochet in the store but if you do both, add an additional 25%. As always, your mileage may vary, but this is a good rough estimate to start with.
• There are also knitting calculators out on the web! Jimmy Beans has one as does Knittable.
• Again, if you're unsure round up as an extra skein of yarn can always find a home, but a sweater with only 1.5 sleeves is less fun.
• Find a similar style thing you want to make on Ravelry and use their yarn requirements as a guide. Especially if you are doing something with cables because that uses more yarn!

DO I HAVE ENOUGH TO FINISH (A.K.A. WILL I WIN AT YARN CHICKEN)?

• For this, you need a kitchen scale! Weigh your project without the extra yarn or needles. It's fiddly but doable. Then weigh the amount of yarn you have left. Depending on where you are in the pattern you should have a pretty good idea of how much yarn you will need vs what you actually have left. May the odds be ever in your favor!