PLAN WHAT TO BUY
Crochet yarn calculator
Turn a measured swatch and your target size into grams, yards and balls.
How to calculate yarn for a crochet blanket
Measure the complete area and yarn weight of a representative finished swatch. Divide your target body area by the sample area, then multiply by the sample weight. Add your chosen planning allowance, subtract matching yarn already owned and round the shortfall up to whole balls.
Worked example
A 100 × 150 cm body and a 10 × 10 cm sample weighing 5 g give 750 g of body yarn. Adding 10% gives 825 g. If you already own 200 g and each new ball contains 100 g, you need seven new balls. If each ball has 200 m, the total 825 g plan corresponds to 1,650 m.
Why use a swatch instead of yarn weight alone?
Yarn thickness, stitch pattern, hook, tension and finishing can all change consumption. We use your measured fabric rather than assigning a fixed yardage to a thickness category. See the full yarn planning example.
Can this calculate garments, borders or colorwork?
The model is for a flat rectangular body in one representative yarn and stitch. It does not model shaped garments, floats, fringe or a separate border. For several colors, estimate each color’s need and whole-ball purchase separately.
What if I only know how much yarn I have?
Use the stash blanket calculator to work backwards to a possible length at your chosen width. Neither calculator guarantees an exact finished size or enough yarn; your sample is an estimate of the fabric you will make.
Method maintained by Loop & Yard. Published 2026-10-30. Examples illustrate the formulas; they are not measurements of a tested finished blanket.