Yarn Calculator
Estimate how many balls of yarn a knitting or crochet project needs.
About the Yarn Calculator
Enter the yarn length the pattern needs, the length on each ball or skein and an allowance for extra. The calculator gives the number of balls to buy and how much will be spare.
Patterns list total yardage. When substituting yarn, compare by length, not weight, because yarns of the same weight can differ greatly in yardage. Add 10% if you're changing size, length or gauge, and buy everything in one dye lot.
The formula
Balls = ⌈pattern length × (1 + extra) ÷ length per ball⌉
Worked example
A pattern needing 1,200 yards, balls of 200 yards, plus 10%
- 1,200 × 1.1 = 1,320 yards
- 1,320 ÷ 200 = 6.6, so buy 7 balls
- 80 yards to spare
Questions people ask
Yards or metres?
1 yard = 0.9144 m; use the same unit for both inputs.
Can I mix dye lots?
Alternate rows from both lots to blend any difference.
Why compare by length, not weight?
Two 100 g balls can hold very different lengths; patterns are written for length.