Yarn Calculator
Estimate blanket yarn from a weighed swatch, preview repeating stripes, subtract partial balls and print a colour-by-colour shopping list.
YOUR SWATCH → YOUR BLANKET → YOUR SHOPPING LIST
How much yarn should you buy?
Use a weighed swatch to estimate a plain or striped blanket. Account for yarn you already have, then buy whole balls for each colour.
1,650 g including 10% reserve · 3,300 yd estimated yarn · 1 colour
See the colour-by-colour plan ↓The starting values are an example, not a generic yarn allowance. Replace them with your own swatch. This plan covers the rectangular body only, without borders or fringe.
1 · The blanket body
2 · Weigh your swatch
Use the same yarn, stitch and tension. Measure the full dry, prepared rectangle you weigh—not just its centre. Leave out long loose tails.
3 · Read the yarn label
All colours use the same yarn construction and ball size. Changing fibre, thickness or stitch needs a new swatch.
4 · Colours & yarn you own
One colour makes a plain blanket. Add colours for repeating stripes, starting with the first colour below. Available grams should exclude yarn still tied up in your swatch.
Up to 8 colours. A partial last stripe is included automatically.
Your fabric & shopping plan
Start at the top. Select a colour in the preview to edit its yarn or stripe. Colours are also listed by name below.
200 stitches × 300 rows
Requested 40 in × 60 in; planned 40 in × 60 in. Check your stitch-pattern multiples.
1 · Sage · 300 rows
Buy 17 balls- Base fabric estimate
- 1,500 g
- Including 10% reserve
- 1,650 g · 3,300 yd
- Already available
- 0 g
- Left after reserved use
- 50 g
Yarn usage is an estimate from your swatch. Borders, fringe, shaping and different stitch patterns are outside this plan. Buy matching dye lots where possible.
How to read the plan
The calculator rounds the target width and length up to whole stitches and rows using your swatch. Check the displayed planned size: it can exceed the requested size. Counts are not a cast-on or turning-chain instruction. If your pattern needs multiples of stitches or rows, adjust the requested size to suit that repeat.
Base yarn is the estimated fabric consumption. Reserve is your additional allowance. The shopping list subtracts available yarn, then rounds the shortfall up to whole balls separately for each colour. “Left after reserved use” includes unused stash and purchase surplus; it is not the amount predicted to remain after actual knitting.
Use the same stitch pattern and yarn construction in every colour. This tool does not model stranded colourwork, floats, shaped garments, motifs, borders, fringe or seams. Ends and stitch tension vary; a percentage alone cannot guarantee enough yarn. Check dye lots before buying.
Formula, precision & limits
Body stitches = requested width ÷ swatch width × swatch stitches, rounded up. Body rows use the equivalent height calculation. The stripe cycle repeats in order and stops at the last body row. Each colour’s base grams = swatch grams × body stitches × colour rows ÷ (swatch stitches × swatch rows). Required grams = base grams × (1 + reserve/100). Balls to buy = remaining required grams ÷ grams per ball, rounded up, with a minimum of zero. Label length converts the estimate to yards or metres.
This proportional model assumes the small swatch represents the whole fabric. Edges, starting chains, bind-offs, tension and measuring error can change actual consumption. Rounded output is an estimate; whole-ball calculations use exact input fractions, not the rounded displayed grams.
Decimals accept a dot or comma, up to six decimal places. Swatch sides: 0.1–100 cm; body sides: 0.1–1,000 cm; swatch stitches/rows: 1–1,000 each. Swatch mass: 0.001–1,000 g; ball mass: 0.001–10,000 g; label length: 0.001–100,000 m; available yarn: 0–100,000 g per colour; reserve: 0–100%; stripe length: 1–1,000 rows. Maximum planned width/height: 20,000 stitches/rows. These are software limits, not measurement accuracy.
For the role of a project swatch, see the Craft Yarn Council’s gauge guidance. The yarn purchasing model above is our proportional estimate.
