# Crochet sphere calculator

> Work out a crocheted ball of any size: enter a finished diameter and your stitch gauge and get every increase and decrease round, as a pattern rather than a table.

**The maths, stated plainly.** A crocheted sphere is two domes back to back. You start with six stitches in a magic ring and add six every round, so after **n** increase rounds the widest round has **6n** stitches. That widest round is the circumference at the equator measured in stitches — so a stitch gauge turns it into a circumference in centimetres, and the diameter is that divided by π. Then you work straight for about as many rounds as you increased, and decrease in the mirror image of the way up, which is why the second half of the pattern needs no arithmetic of its own.

**Gauge is the whole game.** Every number is a multiple of one measurement, and amigurumi is worked far tighter than a ball band assumes — usually a hook a size or two below what the yarn suggests, so the stuffing cannot show through. The calculator accepts 2 to 40 increase rounds.

## Common sizes at 20 stitches per 10 cm

| Increase rounds | Widest round | Rounds to work | Stitches in total | Finished diameter |
| --- | --- | --- | --- | --- |
| 3 | 18 sts | 8 | 108 | 2.9 cm |
| 5 | 30 sts | 14 | 300 | 4.8 cm |
| 8 | 48 sts | 23 | 768 | 7.6 cm |
| 12 | 72 sts | 35 | 1728 | 11.5 cm |

Worsted-weight yarn worked tightly, which is the commonest amigurumi gauge. A different gauge moves the last column and nothing else.

## What a five-round ball looks like

```
Pattern name: "Ball"
start: magic ring

// generated by the crochet sphere calculator — edit freely
Round 1: 6 sc in ring → 6
Round 2: inc x6 → 12
Round 3: (sc, inc) x6 → 18
Round 4: (2 sc, inc) x6 → 24
Round 5: (3 sc, inc) x6 → 30
Round 6-10: 30 sc → 30
Round 11: (3 sc, dec) x6 → 24
Round 12: (2 sc, dec) x6 → 18
Round 13: (sc, dec) x6 → 12
Round 14: dec x6 → 6
fasten off
```

That is the tool's actual output, in the notation the planner reads. Half of it is a dome: work the increase rounds and stop, which is also how a flat-bottomed head or a paw pad starts.

**Shapes are not copyrightable**, and a sphere least of all. Take the rounds, sell what you make from them, put them in your own pattern.

The page itself — the calculator, a button that opens the pattern in the 3D planner, and six questions answered — is at [https://crochet3d.com/tools/crochet-sphere-calculator](https://crochet3d.com/tools/crochet-sphere-calculator).

Source: https://crochet3d.com/tools/crochet-sphere-calculator