Leftover Yarn Calculator
Weigh what's left of a partial skein on a kitchen scale, and this converts that weight into an actual remaining yardage — then checks it against whatever patterns you're considering, so "probably enough" becomes an actual yes or no.
Your leftover yarn
Patterns you're considering
Enter the yardage each pattern calls for. Leave a row's yardage at 0 to skip it.
Why weight converts to yardage this way
Yarn is spun to a fairly consistent thickness along its length, so weight and length stay proportional within the same put-up — half the weight of a skein is very close to half its yardage, give or take the small irregularities in any handmade or machine-wound strand. That's the whole calculation here: your remaining weight divided by the full skein's weight gives the fraction of the skein you have left, and that same fraction of the full yardage is your remaining length. It only works within the same dye lot and put-up you're measuring against — a partial ball of one brand's worsted weighed against a different brand's yards-per-gram will be off, since different fibers and spins pack differently even at the same weight category.
Why this beats eyeballing a ball of yarn
A leftover ball's visual size is a poor guide to remaining yardage because winding tension changes how compact it looks — a loosely wound leftover ball can look like plenty of yarn and come up short, while a tightly rewound one can look like a small amount and still have enough. Weight doesn't lie the way visual bulk does, which is why kitchen-scale weight is the number worth trusting over a guess by eye, especially before starting a project you can't easily frog partway through, like anything with a color-work or cable section.
When you're close but not quite there
If a pattern needs slightly more than you have left, a small deliberate substitution is usually less noticeable than running out mid-row: working a contrasting-color border, edging, or trim in a coordinating scrap yarn on just the last few rounds or rows reads as an intentional design choice far more often than it reads as a mistake, and it can be the difference between a finished project and a UFO stalled two rows from the bind-off.