Strawberry jam (powdered pectin)

This is the tested strawberry jam with powdered pectin published by the National Center for Home Food Preservation, not a house formula ¹. If you change the fruit, sugar, or acid, you are no longer on a tested preserve — read Jam and Pectin before improvising, and do not water-bath an invented jam recipe. See Food safety.

1. Sort and wash ripe strawberries; cap them; crush. Measure 5½ cups crushed fruit ¹.
2. Stir in one package of powdered pectin. Bring to a full rolling boil, stirring constantly.
3. Add 8 cups sugar. Return to a full bubbling boil and boil hard 1 minute, stirring.
4. Remove from heat; skim. Fill hot sterile jars with ¼ inch headspace.
5. Process half-pints or pints in a boiling-water canner: 5 minutes at 0–1,000 ft, 10 minutes at 1,001–6,000 ft, 15 minutes above 6,000 ft ¹.