How to use the crochet ball pattern calculator
- Crochet a flat swatch in single crochet with the yarn and hook you will use for the toy. Work it as tightly as you plan to work the ball.
- Count the stitches across and the rows down 4 inches or 10 cm.
- Enter the diameter you want and your two gauge numbers. Leave the magic ring at 6 unless your pattern starts with a different count.
- Follow the round list. Copy it or save the PDF so you can tick rounds off as you go.
How the sphere math works
A ball has three parts. The top is a flat circle that grows by 6 stitches each round until it is as wide as the ball. The middle is a band of even rounds with no shaping. The bottom mirrors the top, losing 6 stitches each round until only the starting stitches are left.
The widest round has to go all the way around the ball, so its length is the circumference: π times the diameter. Multiply that by your stitches per inch to get the stitch count. For the height, picture a line from the top of the ball to the bottom over the surface. It is half the circumference, and your row gauge turns that length into rounds.
Formulas
- Widest round = π × diameter × stitches per inch, rounded to a multiple of 6.
- Increase rounds = widest round ÷ 6.
- Total rounds = π × diameter ÷ 2 × rounds per inch.
- Decrease rounds = increase rounds − 1.
- Even rounds = total rounds − increase rounds − decrease rounds.
Worked example: a 3 inch ball
With 20 single crochet in 4 inches, there are 5 stitches per inch. The circumference is 3.1416 × 3 = 9.42 inches, and 9.42 × 5 = 47.1 stitches. The nearest multiple of 6 is 48, which takes 8 rounds: 6, 12, 18 and so on up to 48.
The height over the ball is 9.42 ÷ 2 = 4.71 inches, and at 5 rounds per inch that is 23.6, so 24 rounds. Decreasing back down from 48 to 6 takes 7 rounds, which leaves 24 − 8 − 7 = 9 even rounds in the middle. If your rows were taller, say 24 rounds per 4 inches, the same ball would need 28 rounds and 13 of them even.
Ball sizes at a common gauge
These counts use 20 stitches and 20 rounds per 4 inches, starting with 6 in a magic ring.
| Diameter | Widest round | Increase rounds | Even rounds | Total rounds |
|---|---|---|---|---|
| 1.5" | 24 sts | 4 | 5 | 12 |
| 2" | 30 sts | 5 | 7 | 16 |
| 3" | 48 sts | 8 | 9 | 24 |
| 4" | 60 sts | 10 | 12 | 31 |
| 6" | 96 sts | 16 | 16 | 47 |
Same ball pattern, different yarn
A crochet ball pattern written for one yarn makes a different size ball in another. This table holds the diameter steady and changes the gauge, with stitches and rounds the same size. Each cell shows the widest round and the total rounds.
| Diameter | 16 sts per 4" | 20 sts per 4" | 24 sts per 4" |
|---|---|---|---|
| 2" | 24 sts, 13 rnds | 30 sts, 16 rnds | 36 sts, 19 rnds |
| 3" | 36 sts, 19 rnds | 48 sts, 24 rnds | 54 sts, 28 rnds |
| 4" | 48 sts, 25 rnds | 60 sts, 31 rnds | 78 sts, 38 rnds |
| 6" | 78 sts, 38 rnds | 96 sts, 47 rnds | 114 sts, 57 rnds |
Read it the other way to see what happens when you follow a pattern in a different yarn. A 48 stitch, 24 round ball is 3 inches at 20 stitches per 4 inches. Worked at 16 stitches per 4 inches, the same 48 stitches make a ball close to 3.8 inches across. So to scale a ball pattern up or down, change the yarn and hook, or change the number of increase rounds.
How many even rounds? Patterns disagree
The middle band is where published ball patterns differ most. Supergurumi uses one more even round than increase rounds. Zamiguz says to add at least half as many plain rounds as increase rounds, so 3 or 4 after six increase rounds. Its own small ball uses 8 plain rounds after six increase rounds, which is well above that minimum.
The calculator works it out from the height instead. For a ball that increases to 36 stitches over 6 rounds, at 20 stitches and 20 rounds per 4 inches, it gives 7 even rounds. That matches Supergurumi's rule and falls between Zamiguz's minimum and its own example. With only 3 even rounds, the ball would be 4 rounds short of round, which shows as a flattened shape. If your rounds are shorter than your stitches are wide, you need more even rounds, and the row gauge box handles that.
The calculator takes the total rounds from the distance over the ball, top to bottom. That is half the circumference (π × diameter ÷ 2), so the 3 inch ball above needs 24 rounds.
Tips for round amigurumi balls
- Mark the first stitch of each round with a stitch marker. Continuous rounds have no visible seam, so it is easy to lose your place.
- Stagger the increases on every other round to avoid six flat sides.
- The invisible decrease (through the front loops of two stitches) leaves smaller gaps than a standard sc2tog.
- Stuff a little at a time and shape the ball with your hands as you go, so it fills evenly.