Yarn Weight to Length Calculator
The length and weight on the label fix the metres per gram. Put the remainder on a scale and you know what is left, which tells you how many more rows it will carry once you know the length a row eats.
Your numbers
Yarn length needed
1,280m
Metres per gram
4m
Formula
Yarn length needed = Yarn needed × Metres per ball ÷ Grams per ball
Subtract the core or band if the ball is still wound on one. Being 5 g out moves the answer by about 20 m.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Metres per ball (m)Metres in one ball or skein, as stated on the band. | 200 | 1 and up |
| Grams per ball (g)Grams in one ball — usually 50 or 100. | 50 | 1 and up |
| Yarn needed (g)The yarn weight in grams, not a number of balls. | 320 | 0 and up |
Step by step
Quick reference table
Results when only Metres per ball (m) changes and everything else stays put.
| Metres per ball (m) | Yarn length needed (m) | Metres per gram (m) |
|---|---|---|
| 100 | 640 | 2 |
| 150 | 960 | 3 |
| 200 | 1,280 | 4 |
| 300 | 1,920 | 6 |
| 400 | 2,560 | 8 |
What each result means
| Result | At default values |
|---|---|
| Yarn length needed (m)The yarn length in metres, matching the label. | 1,280 |
| Metres per gram (m)Metres per gram — how you read length off leftover weight. | 4 |
Common mistakes
Subtract the core or band if the ball is still wound on one. Being 5 g out moves the answer by about 20 m.
Glossary
- Metres per ball
- Metres in one ball or skein, as stated on the band.
- Grams per ball
- Grams in one ball — usually 50 or 100.
- Yarn needed
- The yarn weight in grams, not a number of balls.
- Yarn length needed
- The yarn length in metres, matching the label.
- Metres per gram
- Metres per gram — how you read length off leftover weight.
Frequently asked questions
Q. How is Yarn Weight to Length Calculator calculated?
Yarn length needed = Yarn needed × Metres per ball ÷ Grams per ball — The length and weight on the label fix the metres per gram. Put the remainder on a scale and you know what is left, which tells you how many more rows it will carry once you know the length a row eats.
Q. Can you walk through an example?
With Metres per ball 200m, Grams per ball 50g, Yarn needed 320g, the answer is Yarn length needed 1,280m.
Q. What do I need to enter?
Enter Metres per ball, Grams per ball, Yarn needed. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Metres per ball (m) moves the answer to Metres per ball (m) 100 → Yarn length needed (m) 640 and Metres per ball (m) 400 → Yarn length needed (m) 2,560. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Subtract the core or band if the ball is still wound on one. Being 5 g out moves the answer by about 20 m.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.