You will need to taste as you go along because summer fruit varies so much in sweetness. Add or subtract the amount of sweetener as needed. It is best to make the jam slightly sweeter than desired in the finished product because it diminishes in sweetness once it is chilled.
6 cups peeled, pitted and sliced peaches
2 cups granulated sugar or to taste
1/4 cup lemon juice or to taste
1/2 cup powdered pectin or equivalent liquid pectin
In large Dutch oven, combine ingredients. Mix well, making sure pectin is dissolved completely.
Bring to a boil over medium-high heat, then cook until jam reaches 220 degrees on candy thermometer or falls in sheets from spoon, stirring frequently. Skim off foam that rises to the surface.
Let jam cool slightly, then spoon into freezer containers. Cover with lids and freeze