Yarn Yardage from Swatch Calculator
Estimate yarn mass, yardage and whole balls by scaling a measured swatch to entered rectangular garment or blanket pieces.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Scale measured swatch yarn mass by total piece area and allowance, then use entered ball mass/length to estimate yarn length and whole balls.
Needed mass=swatch mass×total piece area/swatch area×(1+extra)
Worked example
A 10 × 10 cm swatch using 5 g and two 50 × 60 cm pieces need 300 g before allowance, or 330 g with 10% extra. At 50 g per ball, purchase seven balls.
Assumptions and input details
Use the same stitch pattern, yarn and finished swatch measurement convention as the pieces. Piece rectangles can represent your chosen equivalent area for shaped pieces. Borders, seams, tails, stitch changes, tension and laundering effects are not predicted. Ball length is the supplier/user value, and different yarns cannot be compared by weight alone.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
The 19 mass definitions distinguish avoirdupois and troy measures, metric and regional measures. Japanese kin is 600 g; mainland Chinese shijin is 500 g.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Turn a measured swatch into stitch and row counts, including pattern repeats and edge stitches.
Compare tex, denier, metric count and English cotton count by the same yarn linear density.
Distribute one-stitch increases or two-to-one decreases among unchanged stitches while preserving exact input/output counts.
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