If you have the original yarn label, estimate remaining length by multiplying remaining yarn weight by the label’s length-to-weight ratio. You need both numbers: grams alone cannot tell you the length of an unknown yarn.
Weigh only the yarn
Remove packaging, a paper band, needles and other items before weighing. If the yarn is on a core or bobbin, subtract its empty weight. For several partial balls of the same yarn, add their net weights. Keep different yarns separate because their meters per gram can differ.
Read the ratio from the label
For a yarn labeled 100 g / 240 m, the ratio is 2.4 meters per gram. A 37 g remainder is approximately 88.8 m. Divide meters by 0.9144 to get yards: approximately 97.1 yd. The calculator shows both units so you can compare the estimate with a pattern.
Why the answer is approximate
This assumes the remaining yarn has the same average length per gram as the labeled skein. Scale precision and yarn condition affect the usefulness of the result. If a scale only reads whole grams, a tiny remainder may have a large relative measurement error. Show the result as an estimate rather than interpreting decimal places as precision you actually measured.
If the original label is missing, a known-length sample that you can weigh can establish an approximate ratio. A yarn weight category alone cannot supply the missing meters per gram.
Use the length in a project
Compare the estimate with the pattern’s length requirement, allowing for your chosen reserve. For sizing a blanket directly from grams, the stash planner uses your swatch instead. See how to read a yarn label to keep package weight and thickness category separate.
Use the calculator ↗Examples illustrate the arithmetic; they are not physical project tests. Send a correction.