Amigurumi Round Counter
Enter the diameter you want and your gauge, and get a round-by-round stitch count plan for a sphere — starting from a 6-stitch magic ring.
How this pattern is built
This uses the standard amigurumi sphere technique: start with 6 single crochet in a magic ring, increase by 6 stitches every round until you reach the stitch count needed for your target circumference, work any straight rounds at that width, then mirror the increases as decreases back down to 6 and cinch closed. It's the same shaping logic used in most amigurumi patterns, just generated for your specific size instead of a fixed one.
Invisible decrease vs standard decrease
The decrease rounds this generates assume a standard single crochet decrease (working two stitches together), but most experienced amigurumi crocheters switch to an invisible decrease for the shaping rounds — it works through only the front loops of two stitches instead of both full stitches, which avoids the small visible bump a standard decrease leaves. On a sphere's surface, where every stitch is visible and there's no seam to hide it in, that difference matters more than it would on a garment. The stitch counts from this calculator are identical either way; only the technique for working each decrease changes.
Gauge tighter than you'd use for a garment
Amigurumi is typically worked one hook size smaller than the yarn label suggests, specifically to close up the natural gaps between stitches — a garment gauge is comfortable to wear, but the same looseness on a stuffed toy lets the polyester fiberfill show through as light-colored specks between stitches. If your finished piece looks a little "fuzzy" with visible stuffing at the surface, that's usually a gauge problem rather than a stuffing problem — try a size smaller hook before adding more filling.
Stuff as you close the final rounds, not all at once at the end — it's much easier to work stuffing into a mostly-open sphere in small amounts each round than to force a fistful in through a nearly-closed 6-stitch opening. Slightly overstuff rather than understuff; amigurumi pieces that feel a little firm hold their shape far better over time than ones that feel soft, which tend to develop dents.