The pectin calculator can be found here
4 cups blueberries, fresh or frozen
1 cup maple syrup
5 tablespoons Ball® RealFruit™ Low or No-Sugar Needed Pectin
1 ½ cups of brown sugar
3 tablespoons bottled lemon juice
Yields 6 half-pint jars
Prepare hot water bath, jars, rings and lids.
Combine blueberries with maple syrup and lemon juice in a non-reactive pot. Mash gently. Gradually stir in Ball® RealFruit™ Pectin. Bring mixture to a full rolling boil that cannot be stirred down, over high heat, stirring constantly.
Add brown sugar. Return mixture to a full rolling boil. Boil hard 1 minute, stirring constantly. Remove from heat. Skim foam if necessary.
Test and check set.
Ladle hot jam into hot jars, one at a time, leaving 1/4-inch headspace. Wipe rims. Center lids on jars. Apply bands and adjust to fingertip tight.
Place filled jars in canner, ensuring jars are covered by 1 to 2 inches of water. Place lid on canner. Bring water to gentle, steady boil.
Process jars for 10 minutes, adjusting for altitute. Turn off heat, remove lid and let jars stand for 5 minutes.
Remove jars and cool. Check lids for seal after 24 hours.