How to Knit a Helpful Swatch – Part 4 Swatching to Estimate Yardage Needed

August 24, 2020| LindyBeir| 0 Comment | 8:00 am

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I have covered the basics of how to make a Gauge Swatch and calculate your stitch and row gauge in my previous three posts. Today’s topic will cover some basic math to help you estimate the yardage that you need using your yarn, your needles, and your gauge to make a sweater.

Let’s say you want to make a sweater using yarn from your stash and you need to know if you have enough to make it. To make this estimate, you need the measurements for the sweater you want to make. If you are using a pattern, the finished measurements should be stated within the pattern – ideally on a schematic. Some patterns may only state the desired measurements within the text of the pattern and you may have to read through to find them. If you are making the sweater without using a pattern – you would use the measurements of the individual who will be wearing the sweater.

The image below shows a schematic for the back of a sweater of a drop sleeve sweater. The back is 28 inches long from the hem to the neck and it is 20 inches wide. Both the front and the back of this type of sweater are essentially rectangles.

The schematic for the sleeves of this sweater are shown below.

At this point, you have the numbers you need to calculate the number of square inches of fabric that you need to make for this sweater. For the front and back, multiply the length by the width on the schematic and then multiply that number by 2. Using the numbers from my example above:

20 * 28 = 560 560*2 = 1120 square inches for front and back.

The sleeve is a trapezoid shape. The formula for the area of a trapezoid is:

[(b1+b2) * h] / 2

Where b1 is the width at the bottom of the sleeve(8”) and b2 is the width at the top of the sleeve(15”) and h is the length of the sleeve(18”). Using the numbers from the sleeve schematic, the area for one sleeve is 207 square inches. Since you need two sleeves, you then need to multiply the area of the sleeve by two. (414 square inches)

Now, here’s a short cut – if you place your sleeves next to each other so that the tops of the sleeves are parallel – you have a parallelogram. To get the area of this parallelogram you simply multiple the width(15”+ 8” = 23”) by the length(18”). Try it – you’ll get the same number as above.

Add the square inches for the front and back to the square inches for the sleeves and you have the total number of square inches of fabric in the sweater. Now that you know the total number of square inches of fabric you need, you will need to use the yardage and weight information of the yarn you want to use to estimate how many skeins or balls of yarn your sweater requires. The yardage per weight of the yarn will be found on the yarn label – see image below:

You will use the yards per gram value in the estimate for total yardage. Now you need to knit a swatch. The swatch should be in the same stitch pattern that you plan to use for the body of your sweater. This swatch does not need to be the same size as your gauge swatch, but it should be wide enough and long enough to get an accurate weight, length and width measurement. After you knit this swatch, you will measure its weight using a scale that measures to the nearest tenth (0.1) of a gram. Next measure the length and width of the swatch and multiply these values together. This gives you the number of square inches in your swatch. Now divide the number of grams by the number of square inches.(Do not round). You now know what 1 square inch of your yarn weighs. This is the number you need to calculate how much yardage you need for your sweater.

Example: My swatch measures 3.5 inches by 4.5 inches, which gives me 15.75 square inches. The swatch weighs 9.6 g. Dividing 9.6 by 15.76 gives me 0.622 g/square inch.

Here’s the final set of calculations:

Take the total number of square inches of fabric and multiply it by the number of grams per square inch. This gives you the total weight in grams for your sweater.

Total Number of Square Inches * grams/inch² = Total grams of fabric

Total Grams/Square Inches = (1120 + 414) * 0.622 = 954.148 g

Now take the yards per gram value from the yarn label. (For example 218 yds/100grams). Divide the yds by the grams to get the number of yards in 1 gram of yarn. (For example: 218yards/100grams = 2.18 yards per gram.) Multiply the total number of grams of fabric by the number of yards per gram to get the total yardage for the sweater. Using the numbers from the examples above:

Yards per gram = 2.18 yds/g

Total Yards of Yarn = 954.148 * 2.18 = 2080 yds

To determine the number of skeins, balls or hanks of yarn you need: Divide the number of yards by the number of yards in the skein. Or divide the total number of grams by the number of grams of the skein. Remember that you will want one extra skein for swatching. (In my example, I would need 9.5 skeins, so I would want 11 skeins with one extra for swatching)

What to do if you don’t have the yarn label

To determine how many yards of yarn you have when you do not have the yarn label or any information, simply measure out 10 yards of your yarn and weigh it. Divide the weight by 10 and you have the weight for 1 yard of yarn. Now weigh the skeins/hanks of yarn and multiply by the weight of 1 yard. This will give you the number of yards for each skein/hank.

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Summer Knitting: Dishcloths # 4 – 6Summer Knitting: Dishcloths # 4 – 6

I am now half way through my Summer Knitting project of knitting a dozen dishcloths. Here are the three I have just finished:

Dishcloth #4 – Crocus Buds

Pattern from the Leisure Arts “Knitting Kitchen Brights Dishcloths” brochure. Yarn: Lion Brand Kitchen Cotton, color Banana. This was an interesting openwork pattern. The “crocus buds” are created by pulling a stitch over the next two stitches on the needle. It is a simple 6 stitch pattern over 4 rows with yarn overs creating the open patterning between the “crocus buds”.

Dishcloth #5 – Elfin Lace

Pattern from Leisure Arts “Knitting Kitchen Brights Dishcloths” brochure. Yarn: Lion Brand Kitchen Cotton, color Natural. Easy lace pattern, that knits up into a nice dishcloth. The Elfin Lace pattern is an eight stitch pattern done over 8 rows.

Dishcloth #6 – Trinity Stitch

Pattern from Leisure Arts “Knitting Kitchen Brights Dishcloths” brochure. Yarn: Lion Brand Kitchen Cotton, color Natural. Lovely textured pattern produced by using the “Trinity Stitch”. I loved knitting this one. The “Trinity Stitch” is a neat textured pattern.

Link to “Kitchen Bright Dishcloths” from Leisure Arts (2004).

FO: Basic Anklets — Cuff DownFO: Basic Anklets — Cuff Down

After doing two pairs of the “Fancy Feet” Anklets, I came to the following conclusions:
1) I really, really do not like to knit socks of any type toe-up. (I know that may shock those of you that swear toe-up is the only way to go — but there it is. I just don’t like to knit ’em that way.
2) I don’t like the repeating short rows that make the heel on this pattern. I don’t care for it’s depth or it’s shape.
3) I prefer using the German Short Row method over the “Wrap and Turn” method.

As knitters, we do have the right to our preferences. These are some of mine.

That said, I got out my needles and some leftover sock yarn and started working on a basic anklet pattern, cuff down. I have now finished my first pair and my notes are a bit sketchy — so I will need to knit a couple more pairs before I put out my basic pattern. But here a couple of pictures of the completed anklets:

Details:
Yarn: Leftover Serendipity yarn in colorway Amethyst
Needles: US 2 (2.50 mm) circulars, 48″
Magic Loop method. Pattern has a basic rib cuff and a short-row heel. Knit in stockinette stitch.

You will note the pooling on this yarn. I wrote about how this variegated yarn pools depending on the size of needles and the number of stitches back in 2010. If you’re interested here’s the link: A Study of Pooling in a Variegated Sock Yarn

Helpful Swatch Part 5: Substituting One Yarn for AnotherHelpful Swatch Part 5: Substituting One Yarn for Another

Many times a knitter will select a pattern to knit only to discover that the yarn used in the pattern is either not available or there isn’t a sufficient quantity available for purchase or it costs more than what the budget allows. So, that leads to finding a reasonable substitute to use. I have seen many forum posts in Ravelry where knitters have had difficulty making a proper substitution.

The first step in substituting one yarn for another is to look for a yarn of similar fiber composition that has approximately the same weight and recommended gauge as the yarn listed in the pattern. By this, I mean if the yarn used in the pattern is worsted weight (size 4), it’s best to find another worsted weight yarn to use as the substitute. If you are purchasing from a local yarn shop, the staff may help you find a substitute. If shopping online, Yarnsub.com is a helpful website that can be used to guide your initial search. Another resource is Ravelry – if the pattern is available in the Patterns database, you can look at others’ projects to see what yarns have been used. Regardless, once you pick your substitute yarn – you’ll need to swatch to find your gauge before you cast on and begin knitting the pattern.

Question: “I’m not getting the same gauge with my substituted yarn as the gauge stated in the pattern – what do I do now?

Here are some options to consider:

Change needle size and reknit the swatch to see if you can match the gauge. If you are getting more stitches than the stated gauge – go up one or two needle sizes. If you are getting fewer stitches than the stated gauge – go down one or two needle sizes. If you succeed in matching gauge with the change in needles and you like the fabric you are producing, then simply follow your pattern and knit with the size needle that helps you get gauge.
If you still can’t get gauge after changing needle sizes, but you like the fabric you are getting, calculate the number of stitches you need to cast-on to match your chest measurement and check the pattern to see if there is a size that uses the same number of stitches. You may still need to make adjustments in shaping if your row gauge is different from the pattern.
Use the pattern as a guide only – use the schematic plus any adjustments you need to make and then determine the stitch counts and rows needed to make the garment with your own gauge. (A good reference for this is Knitting Pattern Essentials by Sally Melville)

Here’s the next issue for substituting one yarn for another: Does the substitute have the same weight and yardage as the original yarn? If it does – you are in luck and can simply buy the same amount of yarn as what is given in the pattern for the size of the garment you want to knit. (Remember to buy an extra one for swatching.) However, in most cases there is a difference in yardage and/or weight between the substitute and the original yarn – which leads to the question: “How much of my substitute yarn do I need? This brings us back to the basic math I covered in my previous post: “To determine the number of skeins, balls or hanks of yarn you need: Divide the number of yards by the number of yards in the skein. Or divide the total number of grams by the number of grams of the skein. Remember that you will want one extra skein for swatching. “