Buy for the make, use your stash
Yarn skein calculator: how many balls do you need?
The quick answer
Convert the pattern requirement and the yarn label to the same length unit, subtract the matching yarn you already have, divide the shortfall by the length of one full skein, and round up. Use the requirement for your chosen size and calculate each color separately. This calculator includes full skeins, partial leftovers, and an optional extra allowance.
On this page
Plan from your stash
How many skeins do you need?
The amount specified for your chosen size and this color.
Use the label of the exact yarn you plan to use.
Only count matching yarn that is not reserved for another project.
Total length of matching leftovers, excluding the full skeins above.
Optional planning allowance for swatching or changes. Check whether your pattern already includes it. No percentage guarantees enough yarn.
Weighing your leftovers instead? Convert grams to length first. Calculate each color separately.
Additional full skeins to buy
2 skeins
- Required
- 900 m
- Already available
- 517 m
- Shortfall
- 383 m
Starting with no yarn: 5 full skeins. Additional skeins are rounded up after subtracting your available yarn.
Free to use. Values stay in this page and are not saved to Stashora or Ravelry. The estimate uses label lengths; check gauge, yarn suitability, and dye lots before buying.
The formula for skeins to buy
Additional skeins = round up(maximum of 0 and [required length − available length] ÷ length per full skein). Available length = full skeins already on hand × label length + matching leftover length. The calculator first converts the pattern requirement into the unit on your yarn label.
If you choose an extra allowance, required length = pattern requirement × (1 + allowance ÷ 100). The default is no extra allowance. Check the pattern’s assumptions before adding more: its stated quantity may already include swatching or a buffer.
Sources: Craft Yarn Council: reading a yarn label · NIST: yards and meters
Example: a 900-meter project and yarn already on hand
Starting with no yarn, the same 900-meter project would need five 220-meter skeins. Counting what is already available changes the purchase to two. These figures illustrate the arithmetic; they are not the requirement for a specific pattern.
| Step | Calculation | Result |
|---|---|---|
| Pattern requirement | Chosen size, one color | 900 m |
| Two full skeins | 2 × 220 m | 440 m |
| Partial skein | 35 g × 220 m ÷ 100 g | 77 m |
| Available length | 440 m + 77 m | 517 m |
| Shortfall | 900 m − 517 m | 383 m |
| Additional full skeins | 383 m ÷ 220 m = 1.74; round up | 2 skeins |
Which number should you take from the pattern?
The calculator needs an existing length requirement. It does not estimate a sweater, blanket, or scarf from dimensions alone. Stitch pattern, gauge, size, and yarn affect consumption.
- Choose the yardage or meterage for the size you will make, rather than the entire range of sizes.
- For multiple colors, calculate the requirement and matching stock for each color separately.
- For yarn held double, check whether the pattern’s stated length already includes both strands. Enter the total yarn length required; the calculator does not double it automatically.
- If a pattern lists only balls of a specified yarn, multiply its ball count by that yarn’s label length to obtain the stated total. Check gauge and suitability before using another yarn.
Sources: Craft Yarn Council: reading a yarn label · Craft Yarn Council: standard yarn weight system
Count only yarn that is actually available
Use the label for the exact yarn, and keep color and dye lot visible in your inventory. Only include full skeins and partial lengths that you are prepared to use for this project. Leave out yarn already reserved for another make.
The partial-skein field is a length in your yarn label’s unit. If you have several matching leftovers, add their lengths. If you have their combined weight instead, convert it with the yardage calculator first. Do not count the same full skein in both fields.
Why round up to a full skein?
A 383-meter shortfall divided by 220 meters per skein is about 1.74 skeins. If your shop sells full skeins, you need two. The calculator subtracts your stock before rounding; it does not round every partial leftover separately.
Label quantities and leftover measurements are estimates. An extra allowance is a planning choice, not a guarantee. If your supply is close to the requirement, check your swatch, pattern modifications, dye lots, and the possibility of obtaining matching yarn later.
Frequently asked questions
How many balls of yarn do I need?
Divide your pattern’s required yards or meters by the length of one ball and round up. If you already own suitable yarn, subtract its length first. Use the requirement for your chosen size and calculate each color separately.
Can the pattern use yards and the yarn label use meters?
Yes. Select the correct unit for each. The calculator converts the requirement into your label’s unit using 1 yard = 0.9144 meters, then subtracts your available yarn.
How do I include partial balls of yarn?
Enter the total length of matching leftovers in the partial-skein field. If you only know their weight, use the yardage calculator with the exact yarn’s label to estimate length first.
Should I always add 10 percent extra yarn?
No single percentage guarantees enough yarn. Check whether the pattern already allows for swatching, and consider your gauge, modifications, and measured stock. Extra allowance is optional and defaults to zero.
Can this calculator tell me how much yarn a blanket needs?
It can convert a blanket pattern’s stated length into skeins to buy. It cannot predict consumption from dimensions alone; use a suitable pattern or a measured swatch calculation to establish the length first.
Is this skein calculator free?
Yes. It runs in your browser without an account. It does not save your inputs or write the result to Stashora or Ravelry.
Sources and review
Written by Stashora. Product details checked on September 30, 2026. Worked examples and checklists are illustrative; they are not performance tests. Read our editorial policy.
