Yarn Yardage Calculator
Yarn is sold by weight but used by length, so a leftover ball's true yardage depends on the yards per gram of that specific yarn. Enter a full skein's length and weight from the ball band, then the weight of a partial ball, and this tool gives the remaining yardage. Enter your pattern's required yardage too and it tells you how many full skeins to buy.
Yarn yardage formula
Yards per gram = full skein yards / full skein grams
Partial ball yardage = yards per gram * partial grams
Skeins needed = ceil(project yardage / full skein yards)
Project yarn weight = project yardage / yards per gram
Everything keys off the yards-per-gram ratio from your ball band, so the estimate matches your actual yarn rather than a generic average.
Worked example
A worsted skein lists 220 yards in 100 grams, so yards per gram = 2.20. A 35 gram leftover ball holds 2.20 times 35 = 77.00 yards. A pattern needing 900 yards takes ceil(900 / 220) = ceil(4.09) = 5 skeins, and uses 900 / 2.20 = 409.09 grams of yarn.
Yarn yardage: frequently asked questions
How do you calculate yardage from yarn weight?
Use the ratio printed on the ball band. If a full skein lists its total yards and total grams, the yards per gram is yards divided by grams. Multiply that by the weight of any partial ball to get its remaining yardage.
How many skeins do I need for a project?
Divide the total yards the pattern calls for by the yards in one skein, then round up to a whole skein. Buying one extra skein from the same dye lot is common insurance against running short.
Why use yards per gram rather than guessing?
Yarn is sold by weight but knitted and crocheted by length, and the yards per gram differs between fibres and yarn weights. Using the label's own yards-per-gram keeps the estimate true to the specific yarn rather than a generic assumption.
Does this work in metres and ounces?
The arithmetic is unit-agnostic as long as you are consistent. Enter the skein's length and weight in whatever units the label uses (yards and grams, or metres and grams), and the result comes out in the same length unit.
Sources and notes
- The calculation is a direct proportion from the length and weight printed on your yarn's ball band.
- Yardage and weight figures come from your specific yarn label; this tool does not assume a brand or fibre.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.