A small swatch. A bigger picture.
Blanket yarn calculator: plan from your swatch
Estimate yarn for a knitted or crochet blanket from its size and a weighed swatch. Get grams, yards, meters, and whole skeins. Free, no account needed.
From a small swatch to a big plan.
Estimated yarn, including allowance
4skeins
Rounded up to whole 100 g skeins
- Weight
- 396 g
- Meters
- 871.2 m
- Yards
- 952.8 yd
- Fabric before allowance
- 360 g
For a rectangular blanket in the sampled fabric. Borders, fringe, different stitches and color changes need separate planning. Add yarn for the swatch if you will keep it.
See the calculationThe quick answer
Estimate blanket yarn by multiplying the whole swatch’s weight by the ratio of blanket area to swatch area. Then use your yarn label to convert grams into yards, meters, and skeins. This works for a rectangular blanket made in the same yarn, stitch pattern, and tension as your sample; size alone cannot tell you how much yarn to buy.
On this page
Start with the fabric you actually want to make
Make a representative sample with your intended yarn, needles or hook, and stitch pattern. Wash and dry it as you intend to care for the blanket, following the yarn’s care instructions. Measure its finished width and length without stretching it.
For this area calculation, weigh the entire measured piece. Do not weigh a 20 × 20 cm sample and enter the 10 × 10 cm center used for counting gauge: that would assign all of the yarn to only a quarter of the fabric. Remove tools, labels, and long yarn tails before weighing.
- Use a scale precise enough to measure the sample. A one-gram difference matters more on a tiny swatch.
- Include complete stitch repeats so the sample represents the blanket’s fabric.
- Use the same unit for all four dimensions. The calculator converts dimensions when you switch between centimeters and inches.
Worked example: a 100 × 120 cm blanket
Suppose a dry 20 × 20 cm swatch weighs 12 grams, and your label says 220 meters per 100 grams. You choose an extra 10% for this example. These are illustrative measurements, not a standard requirement for a baby blanket or any particular yarn.
The same-sized blanket made with a different stitch or yarn can consume a different amount. Keep the swatch measurement with the result so the estimate is reproducible. If you keep the swatch, budget its yarn separately from the blanket fabric.
| Step | Calculation | Result |
|---|---|---|
| Area ratio | (100 × 120) ÷ (20 × 20) | 30 swatch areas |
| Main fabric | 30 × 12 g | 360 g |
| With chosen 10% allowance | 360 × 1.10 | 396 g |
| Length | 396 × 220 ÷ 100 | 871.2 m, about 952.8 yd |
| Whole skeins | 396 ÷ 100 = 3.96; round up | 4 skeins |
Choose the allowance for your own project
The 10% starting value is a sample input, not a guarantee or a universal recommendation. Change it to reflect the uncertainty in your sample and your plan. Check your pattern’s stated quantity first if one is available.
A different border, fringe, tassels, seams, and retained swatches require yarn beyond the main fabric. Estimate those elements separately. A percentage does not automatically model a deep cable border or a fringe-heavy design.
- Use the pattern’s requirements when following a tested design in its stated size and gauge.
- Calculate individual colors separately; a total does not tell you how much of each color to buy.
- Check dye lots and available stock before relying on buying one more ball later.
When this estimate is a poor fit
Area scaling assumes similar yarn use across the entire rectangle. A blanket with several stitch patterns, heavily shaped sections, thick borders, or uneven motifs needs a more detailed plan. Sample the different fabrics separately or use the designer’s yardage.
Changing your hook or needle size, tension, washing method, or yarn after measuring can change the result. Recalculate from the final sample. The output is a planning estimate, not a promise that a particular quantity will be enough.
Keep the swatch and yarn decision with the project
Record the sample dimensions, weight, yarn label, tool size, and stitch pattern. Add the final target size and allowance. When you change the plan, you can see which input needs updating.
Stashora can keep your project notes, photos, and yarn details together. This website calculator works separately: it does not save results to the app or sync them with Ravelry.
Frequently asked questions
How much yarn do I need for a crochet blanket?
Use the pattern’s yardage or measure a representative swatch. Multiply the swatch grams by blanket area divided by swatch area, then convert with your yarn label. Dimensions alone do not account for stitch pattern, yarn, and tension.
Does this work for knitted afghans too?
Yes. The area method works for knitted or crocheted rectangular fabric when the swatch and blanket use the same yarn, stitch, and tension. Plan borders, fringe, and contrasting sections separately.
Should I enter the center of my gauge swatch?
Enter the dimensions of the entire piece whose weight you measured. Weighing a whole swatch but entering only its smaller center area overestimates yarn use.
Does the estimate include the swatch?
The fabric result covers the blanket area. If you keep your swatch, add its yarn separately. The optional percentage allowance is a choice, not an automatic calculation of every extra element.
Sources and review
Written by Stashora. Content reviewed on October 17, 2026. Worked examples and checklists are illustrative; they are not performance tests. Read our editorial policy.
