In a large bowl, use a potato masher to mash the chopped mango into small pieces.
Measure out exactly 3 cups mashed mango, then add to a large bowl. (If you have extra mango, reserve it for another use.)
Stir lemon juice into mango, then add sugar and mix well. Let the mixture stand for 10 minutes, stirring occasionally.
After 10 minutes, combine pectin and ¾ cup water in a small pot. Bring mixture to a boil on high heat, stirring constantly. Boil for 1 minute (continuing to stir), then remove from heat.
Add hot pectin to mango mixture, then stir for 3 minutes, or until the sugar is completely dissolved. (This may take longer than 3 minutes.)
Transfer jam to jars, leaving ½-inch of empty headspace at top. Cover with lids.
Let jam stand at room temperature for 24 hours, or until set.
Once jam is set, refrigerate it for up to 3 weeks, or freeze it for up to 1 year. Enjoy!
Notes
Mangos - To make sure you have enough fruit, buy a couple extra mangos (especially if yours are on the small side). Not sure how to peel a mango? Learn how to cut a mango with my easy tips.Follow the Recipe - For best results, it's important to measure accurately and follow the directions as written.Pectin - This recipe was created specifically for Sure Jell Original Premium Fruit Pectin. If you purchased a different brand, use this recipe as a guide, but follow the directions on the box.Reduced Sugar - Your jam will not set up properly if you use less sugar or swap in a sugar substitute. Instead, use Sure Jell Low Sugar Pectin, and follow the directions on the box.More Tips - Check out the info before this recipe card for helpful tips, step-by-step photos, related recipes, and more!