Crochet guide
How to estimate yarn for a blanket from a swatch
Updated by Khokhar Sab
Make a swatch and find out how many yards it used. Divide that by its area to get yards per square inch. Multiply by the blanket's area (including any border) and add a buffer of about 10 percent. Then divide by the yards in one skein to get the number of skeins to buy.
Why a swatch beats a guess
How much yarn a blanket uses depends on the yarn, the stitch, the hook or needle size, and how tightly you work. Two blankets of the same size can use quite different amounts. A small swatch captures all of those at once, so measuring one is the most direct way to estimate your own project.
The method rests on a simple idea. If a 4 inch square uses a certain amount of yarn, a blanket made the same way uses that amount for every 16 square inches it covers.
Step 1: make and measure a swatch
Work a swatch in the yarn, stitch and hook or needle size you plan to use. Make it big enough to measure well. The examples here use a 4 by 4 inch square, which is 16 square inches. Wash and dry it the way you'll treat the blanket, since some yarns change size when wet.
Then find out how much yarn went into it. There are two ways.
Measure the yarn in yards
Measure out a length before you start, say a few yards more than you think you'll need, and measure what's left when you finish. The difference is what the swatch used. Or unravel the finished swatch and measure the yarn straight.
Weigh the swatch in grams
A kitchen or postal scale that reads in grams is often easier. Weigh the swatch, then convert grams to yards using the skein label:
swatch yards = swatch grams ÷ skein grams × skein yards.
For a skein of 200 yards and 100 grams, an 8 gram swatch used 8 ÷ 100 × 200 = 16 yards. Small swatches weigh only a few grams, so a scale that reads to a tenth of a gram gives a better answer. Sarah Maker also suggests trimming the yarn tails short before you weigh, so their extra weight doesn't skew the result.
How big should the swatch be?
Sarah Maker suggests at least a 4 by 4 inch swatch and says a larger one gives a more accurate yardage figure. Secret Yarnery suggests 5 or 6 inches square for blanket planning. The calculator shows why size matters.
Say you misjudge the yarn in your swatch by just 1 yard. On the 4 inch swatch above, the 50 by 60 throw estimate moves from 3,094 to 3,300 yards, a 206 yard jump. Make a 6 inch swatch of the same fabric (it uses 33.75 yards) and the same 1 yard slip moves the estimate by only 92 yards. The bigger swatch spreads any measuring error over more fabric.
Step 2: scale the swatch up to estimate the blanket's yarn
Divide the swatch's yarn by its area. Say your 16 square inch swatch used 15 yards:
15 ÷ 16 = 0.9375 yards per square inch.
Now multiply by the blanket's area. A 50 by 60 inch throw is 3,000 square inches, so it needs 3,000 × 0.9375 = 2,812.5 yards before any buffer.
With the gram swatch above (16 yards in 16 square inches, or 1 yard per square inch), the same throw comes to 3,000 yards. A small difference in the swatch makes a large difference across a whole blanket, which is why it pays to measure carefully.
Another way: yarn per stitch
Some guides count stitches instead of area. Sarah Maker and Heart Hook Home both weigh the swatch, divide by the number of stitches in it, and multiply by the number of stitches in the blanket. For plain fabric the two methods give the same answer.
The example swatch has 14 stitches and 16 rows, so 224 stitches used 15 yards. At that gauge the throw is 175 stitches across and 240 rows long, or 42,000 stitches. Then 42,000 × 15 ÷ 224 = 2,812.5 yards, the same figure as the area method. Counting stitches helps most with a stitch pattern that repeats over several stitches. Heart Hook Home weighs whole repeats of a textured stitch for that reason.
What changes how much yarn a swatch uses
The swatch method works because the swatch is made the same way as the blanket. Change any of these and you need a new swatch.
- Stitch: Sarah Maker notes that short stitches such as single crochet use more yarn than taller ones such as double crochet. Paradise Fibers and Secret Yarnery both say dense, textured stitches like bobbles and waffle stitch use more, and open stitches like granny or shell patterns use less.
- Hook or needle and tension: Secret Yarnery says tight crocheters tend to use more yarn, because their stitches are more compact.
- Border stitch: Wild Woollys suggests a separate swatch or allowance for any section worked in a different stitch, which includes a border.
- Knitting or crochet: the swatch method works the same for both. Wild Woollys warns that there is no reliable one-number conversion between knitting and crochet yarn use. The calculator's quick estimate mode does use one, assuming knitting takes about 77 percent of the crochet figure, and it labels that as a rough guess.
Step 3: add the border
A border adds area all the way around. Work it out as the full size with the border minus the size without it.
border area = (width + 2 × border) × (length + 2 × border) − width × length.
A 2 inch border on the 50 by 60 throw gives (50 + 4) × (60 + 4) − 3,000 = 456 square inches. At 0.9375 yards per square inch that's another 427.5 yards. If the border uses a different stitch, swatch that stitch separately for a closer figure.
Step 4: add a buffer and count skeins
Estimates are never exact. Your tension can drift over a big project, and you need yarn for weaving in ends and joining. The calculator adds 10 percent by default to cover this, and you can raise it for stripes or many color changes.
For the plain throw: 2,812.5 × 1.1 = 3,093.75, which rounds up to 3,094 yards. With 200 yard skeins, that's 3,094 ÷ 200, rounded up to 16 skeins. With the 2 inch border it becomes 3,564 yards, or 18 skeins.
How big a buffer?
Sources disagree a little. Sarah Maker and Paradise Fibers suggest 10 to 20 percent extra. Secret Yarnery suggests 10 to 15 percent, and more for wide borders, joins, tassels or stripes. Wild Woollys uses 10 percent as a default and 15 percent for texture, colorwork or an uncertain gauge. Here is what each choice means for the example swatch:
| Buffer | Throw yards | Throw skeins | Queen yards | Queen skeins |
|---|---|---|---|---|
| 10% | 3,094 | 16 | 9,282 | 47 |
| 15% | 3,235 | 17 | 9,704 | 49 |
| 20% | 3,375 | 17 | 10,125 | 51 |
The throw is 50 by 60 inches and the queen is 90 by 100. On a throw the gap between 10 and 20 percent is 1 skein. On a queen it is 4 skeins, so the buffer choice matters more on a big blanket.
Buy all the skeins from one dye lot if you can. Colors can vary a little between lots, and Secret Yarnery points out that a later skein may not match the same color name exactly.
Yardage for common blanket sizes
The table uses the same swatch as above (15 yards in a 4 by 4 inch square), a 10 percent buffer, no border, and 200 yard skeins. Your own swatch will give different numbers, so treat these as an example of the method rather than a shopping list.
| Blanket | Size (in) | Area (sq in) | Yards with buffer | 200 yd skeins |
|---|---|---|---|---|
| Lovey | 12 × 12 | 144 | 149 | 1 |
| Stroller | 30 × 35 | 1,050 | 1,083 | 6 |
| Receiving | 40 × 40 | 1,600 | 1,650 | 9 |
| Crib | 45 × 60 | 2,700 | 2,785 | 14 |
| Lapghan | 36 × 48 | 1,728 | 1,782 | 9 |
| Throw | 50 × 60 | 3,000 | 3,094 | 16 |
| Twin | 66 × 90 | 5,940 | 6,126 | 31 |
| Full | 80 × 90 | 7,200 | 7,425 | 38 |
| Queen | 90 × 100 | 9,000 | 9,282 | 47 |
| King | 108 × 100 | 10,800 | 11,138 | 56 |
Blanket sizes vary from chart to chart. The blanket size chart lists common sizes from lovey to king.
Sizing a blanket for a bed
A bed blanket covers the top of the mattress and hangs down the sides and the foot. The head end sits against the headboard, so the overhang is added to the length only once. You can also add extra length to tuck under or fold over the pillows.
width = mattress width + 2 × overhang
length = mattress length + overhang + pillow tuck
A queen mattress is 60 by 80 inches. Say you want 12 inches of overhang and a 10 inch pillow tuck. The blanket then needs to be 60 + 2 × 12 = 84 inches wide and 80 + 12 + 10 = 102 inches long. To pick the overhang, measure the mattress depth to cover its edge, or measure from the top of the mattress to the floor for a longer drop. The quilt size chart lists mattress sizes for every bed.
The quick estimate, and why it's a range
If you haven't made a swatch yet, the calculator has a quick estimate mode based on yarn weight alone, using the Craft Yarn Council's numbered weight categories. It uses rough yards per square inch figures for each weight, so it gives a range instead of a single number. For a medium (4) yarn in crochet, it uses 0.75 to 1 yards per square inch. That puts the 50 by 60 throw at 2,475 to 3,300 yards with the buffer.
That's a spread of 825 yards, or 4 skeins. It's fine for a first budget, but a swatch gives you a figure for your own yarn and tension.
Working out your own numbers
The blanket yarn calculator runs all of these steps at once. Enter your swatch in yards or grams, the blanket size or a bed size, a border and a buffer, and it shows total yards, skeins and grams. For blankets made of squares or blocks, the granny square calculator and the C2C calculator handle the layout. Planning a temperature blanket? The temperature blanket planner estimates yarn per color.
Sources
Sarah Maker on how much yarn a crochet project needs (swatch size, yarn per stitch, buffer), Heart Hook Home's swatch method (weighing stitches and repeats), Secret Yarnery's blanket yardage guide (swatch size, stitch density, buffer), Paradise Fibers on blanket yarn (stitch choice, buffer) and Wild Woollys on yardage estimates (borders, knit versus crochet, buffer).
Video tutorial
"The Exact Way I Figure Out How Much Yarn I Need For a Project 🧶 EASY" by Play Hooky with Me, on YouTube. The video loads only when you press play.