Yarn stash batch planner

Making a batch of hats for a charity drive, a pile of blanket squares, or gifts from one big cone of yarn? This planner works out how many of each item your yarn can make. It can make as many as possible of your main item, keep matching sets of one of each, or find the mix that leaves the least yarn behind.

How to use the planner

1. Enter the total yarn you have.
2. List the items you want to make, one per line, with the yarn each takes, for example "Adult hat 190". Put your main item first.
3. Choose a plan: as many of the first item as possible then fill with the rest, matching sets of one of each, or least yarn left over.
4. Set a small reserve for tails and joins (3% by default).

How the planner works

It first takes off the reserve:

Usable yarn = yarn you have × (1 − reserve)

• Most of the first item, then fill: makes as many of the first item as fit, then fills what is left with the other items in list order.
• Matching sets: divides the usable yarn by one of every item, then fills the remainder in list order.
• Least yarn left over: checks every combination of whole items (a knapsack calculation) and picks the one that uses the most yarn. Item amounts are rounded up to the nearest tenth when it searches, so the plan it picks never needs more yarn than you have.

Reading your results

• Items you can make: the total number of items.
• Yarn used: with the share of your stash.
• Left over: including the reserve.
• Your batch: how many of each item, and the yarn each line uses.

Worked example

You have 1,100 yd (five 220 yd balls) and keep 3% back, leaving 1,067 yd. An adult hat takes 190 yd, a child's hat 130 yd and a charity block 45 yd.

• Most of the first item: 5 adult hats use 950 yd. The 117 yd left cannot make a child's hat but makes 2 blocks (90 yd). That is 7 items using 1,040 yd, 94.5% of the stash, with 60 yd left including the reserve.
• Matching sets: one of each is 365 yd, so 2 sets fit, and the rest fills with another adult hat and child's hat: 3 adult hats, 3 child's hats and 2 blocks, using 1,050 yd.
• Least yarn left over: 4 adult hats, 2 child's hats and 1 block use 1,065 yd, leaving only 2 yd beyond the reserve.

Accuracy and limits

• The arithmetic is exact and covered by our automated tests, including a check that a plan never uses more yarn than is usable. The plan is only as good as the yarn per item you enter: take it from the pattern or weigh one finished item.
• Any unit works, as long as you use the same one throughout: you can enter grams for the stash and each item.
• If even the smallest item needs more yarn than you have, try the scrap yarn blanket size calculator.
• Very large stashes are too big for the least-waste search; use one of the other plans.

Common mistakes

1. Listing only big items. With only hats and scarves, any remainder smaller than a hat goes unused. Add a small item, such as a square or a coaster, at the end of the list to use it up.
2. Setting the reserve to 0%. Every new ball and every finished item leaves ends to weave in. Keep 2 to 3% back.
3. Guessing the yarn per item. A small error is multiplied by every item in the batch.

Tips for more accurate results

• If your yarn is several balls in different colours and you want each item in one colour, plan one ball at a time.
• Weigh the first finished item, then update its amount before you make the rest.
• To check what is left on a part-used ball, use the remaining yarn calculator.

Frequently asked questions