As in knitting, shaping in crochet also includes increasing or decreasing of stitches in a pattern. For a stitch increase in single crochet, another single crochet is made in the same stitch. For a stitch decrease, the crochet hook is inserted into two single crochet stitches and then the yarn over loop is pulled through all the loops on the crochet hook. The image below shows one stitch increase and one stitch decrease in single crochet.

The written instructions and video below show how to increase and decrease a stitch in single crochet for right-handed crocheting.

Stitch Increase in Single Crochet:

Written Instructions for Stitch Increase in Single Crochet:

1. Single crochet (Tutorial Series: How to Single Crochet)
2. Insert the crochet hook under both the strands of a stitch
3. Wrap working yarn counterclockwise around hook (yarn over), catch and pull the loop through both the strands of that stitch
4. There are two loops on the crochet hook
5. Wrap the working yarn counterclockwise around hook (yarn over), catch and pull loop through the two loops on the crochet hook (one single crochet stitch made)
6. Repeat Steps 2 to 5 in the same stitch again for one single crochet stitch increase (two single crochet stitches made in the same stitch)

Stitch Decrease in Single Crochet:

Written Instructions for Stitch Decrease in Single Crochet:

1. Insert the crochet hook under both the strands of a stitch as if to single crochet
2. Wrap working yarn counterclockwise around hook (yarn over), catch and pull the loop through both the strands of that stitch (2 loops on the hook)
3. Insert crochet hook under both strands of the next stitch
4. Wrap working yarn counterclockwise around hook (yarn over), catch and pull the loop through both the strands of that stitch (3 loops on the hook)
5. Wrap working yarn counterclockwise around hook (yarn over), catch and pull loop through all three loops on the crochet hook
6. One single crochet stitch decreased
7. Repeat Steps 1 to 5 to decrease one single crochet stitch