Crochet blanket & starting-chain calculator
Plan a width and a compatible stitch-pattern repeat.
How it works
The calculator rounds the target stitch count up to a multiple plus the specified extra stitches. Add turning chains according to your pattern, not a universal rule. Some stitch patterns count the turning chain as a stitch; enter only the additional chains actually required.
A worked example
100 cm at 16 stitches per 10 cm gives 160 stitches. A multiple of 3 plus 1 already fits; adding 2 extra foundation chains gives a starting chain of 162.
Reference: Craft Yarn Council standards