How to make jam, start to finish

A batch of jam runs in four stretches: set up the canner and jars, prepare and measure the fruit, cook it to the set, then fill, process and cool the jars. With a pectin recipe, the cooking itself is short (the hard boil after the sugar goes in lasts exactly one minute), so most of your time goes into preparation and canning. The jars then sit undisturbed for 12 to 24 hours before you check the seals. This page walks through every step in order, using a tested USDA strawberry jam as the worked example, and links to the page that covers each step in depth.

The recipe this page follows

Every step below fits any tested jam recipe, but it helps to see them applied to one. This is the National Center for Home Food Preservation (NCHFP) recipe for strawberry jam with powdered pectin, adapted from USDA Home and Garden Bulletin 56 [1]. It is quoted as published; do not change the proportions.

The recipe expects sterilized jars, 1/4 inch headspace and a boiling water canner [1]. If you are working from a pectin package insert or another tested source instead, use its quantities and its processing times, and keep the two together. Mixing one source's recipe with another's canning chart is an easy way to end up with the wrong time. If you are not sure your recipe counts as tested, start with how to tell a tested recipe from an untested one.

The batch at a glance

Stage 1: Set up the canner, jars and lids

1. Check your jars and bands. Use canning jars (half-pints or pints for jam) and look for nicks on the rims and rust or bends on the bands [4]. Use a new flat lid for each jar [4].
2. Fill the canner and put it on the heat. Fill it about half full of hot water and set the jars on the rack [6]. A full canner takes longer to boil than anything else in the batch, so it goes on first.
3. Sterilize the jars if your recipe's processing time is under 10 minutes. The strawberry recipe above processes for 5 minutes at low elevation, so its jars must be sterilized: covered with boiling water for 10 minutes, plus 1 more minute for each additional 1,000 ft of elevation [2]. When a recipe processes for 10 minutes or more, clean, hot jars are enough [2]. Either way, keep the jars hot in the canner water until you fill them [5]. The UGA youth canning program holds that water at 180°F [6].
4. Prepare the lids as the lid maker directs [5]. Current two-piece lid practice is covered on the two-piece lids page.
5. Measure the sugar into its own bowl now. Both NCHFP's youth curriculum and the pectin maker tell you to measure the sugar before you start cooking [6][3], because once the fruit and pectin boil, you have no time to count cups.
6. Lay out the filling station: a jar funnel, a ladle, a headspace tool or ruler, damp paper towels, a jar lifter and a towel or rack for the hot jars [6].

Stage 2: Prepare and measure the fruit

7. Wash the fruit just before you use it, and don't soak it [6][7]. For the strawberries: sort them, wash fully ripe berries, and remove the stems and caps [1]. Trim bruised spots [6].
8. Crush the fruit in layers with a potato masher, so every piece is broken down evenly [6][3].
9. Measure exactly. Level each cup of crushed fruit, and use exactly the amount the recipe gives [3]. Too much fruit for the pectin and sugar is a common reason a pectin jam stays soft. Weighing the fruit once you know what your cup holds makes the next batch identical; the method is on preparing fruit for jam.

Make one recipe at a time. A doubled batch takes longer to come to a boil and cook, and the extra heating can break down the pectin [8]. The reasons and the published limits are on can you double a jam recipe.

Stage 3: Cook to the set

10. Fruit and pectin first. Measure the crushed berries into a large kettle, add the pectin and stir well [1]. Powdered pectin goes in with the fruit; liquid pectin is a different method that goes in at the end, so the two are not interchangeable [9].
11. Bring it to a full boil over high heat, stirring constantly. NCHFP describes this as a boil "with bubbles over the entire surface" [1]. Kraft Heinz describes a full rolling boil as one "that doesn't stop bubbling when stirred" [3].
12. Add the sugar, continue stirring, and heat again to a full bubbling boil [1].
13. Boil hard for 1 minute, stirring constantly [1]. Kraft Heinz's own word is "exactly" [3]. Start counting when the boil is back to full strength, not when the sugar goes in. The youth curriculum's instruction is short: "Do not boil longer" [6]. Overcooking damages the pectin's ability to gel [10].
14. Take the pot off the heat.

A recipe made without added pectin replaces steps 10 to 13 with a longer boil to a target temperature, 220°F at sea level and lower as you climb [11]. That method, and how to tell when to stop, is on cooking jam to the set and the temperature test.

Stage 4: Skim, fill and close

15. Skim the foam off the surface quickly with a metal spoon [1][6]. Some recipes add 1/2 teaspoon of butter with the fruit to reduce foam, but USDA notes it may cause off flavor in long storage [7]. The trade-offs are on foam: skim it or add butter.
16. Lift out the hot jars, tip the water back into the canner, and stand them on a towel [6].
17. Fill each jar immediately through the funnel, leaving 1/4 inch headspace [1]. Headspace is the gap between the top of the jam and the rim. Check it with the tool and add or remove a spoonful if needed [6].
18. Wipe each rim with a clean, damp paper towel [1]. Any jam left on the rim sits between the lid's sealing compound and the glass.
19. Put on the lids and bands, tightening the bands only fingertip tight [6]: snug when you turn with your fingertips, no force from the wrist.

Stage 5: Process in the boiling water canner

20. Load the jars upright on the rack and lower them into the canner. The water should cover the jar tops by 1 to 2 inches [3][6]. Add hot water from a kettle if it is short.
21. Cover the canner and bring the water back to a boil. Start the timer only when it boils [6], and keep it boiling the whole time [12].
22. Process for the time your recipe gives at your elevation. For the NCHFP strawberry jam in sterilized half-pints or pints, that is 5 minutes at 0 to 1,000 ft, 10 minutes at 1,001 to 6,000 ft and 15 minutes above 6,000 ft [1]. If you skipped sterilizing the jars, the base becomes 10 minutes, plus an altitude adjustment [2]; on the band chart that pairs with the 10 minute method, that is 15 minutes at 1,001 to 3,000 ft [13]. Both systems, and why they must never be mixed, are laid out on processing times by altitude.
23. Turn off the heat, take off the canner lid (tilting it away from you so the steam goes the other way) and wait 5 minutes before lifting the jars out [6].

Stage 6: Cool, check and store

24. Lift each jar straight up without tilting it and set it on a towel or rack, at least 1 inch from its neighbors and out of drafts [6]. Avoid a cold counter [5].
25. Leave the jars alone for 12 to 24 hours while the seal forms and the jam firms [5]. Some jams keep thickening for up to two weeks [4], so don't judge the set on the first evening.
26. Check every seal. A sealed lid is concave and doesn't flex when pressed [6]. Refrigerate any jar that didn't seal and eat it first [6].
27. Remove the bands, wipe the jars, label them with the contents and date, and store them in a cool, dark, dry place [6].

When the jars are cool: seals, storage and soft sets

Your next questions usually come the morning after: whether every lid really sealed and what to do with one that didn't, which is on checking jars and seals, and how long the jars keep, on storing home-canned jam. If a jar is still runny after a day or two, give it the full two weeks before you decide anything, then work through my jam didn't set: can I fix it?.

References

1. National Center for Home Food Preservation, *Strawberry Jam with Powdered Pectin*, June 2005 (adapted from USDA Home and Garden Bulletin No. 56, 1982 reprint); copy hosted by Bethlehem Public Library, NH. https://bethlehemnhlibrary.gov/wp-content/uploads/strawberry-jam-pectin-national-center-for-home-food-preservation.pdf
2. National Center for Home Food Preservation, *Do I need to pre-sterilize my jars before canning?*, blog, May 21, 2014. https://nchfp.uga.edu/blog/do-i-need-to-pre-sterilize-my-jars-before-canning
3. Kraft Heinz, *SURE-JELL Strawberry Jam* (recipe 500467), accessed October 2026. https://www.kraftheinz.com/surejell/recipes/500467-sure-jell-strawberry-jam
4. University of Illinois Extension, *Fill Your Pantry: Jams and Jellies*, July 2021. https://extension.illinois.edu/sites/default/files/jams_and_jellies_fill_your_pantry_final_2021.08.20.pdf
5. Andress, E.L., University of Georgia Cooperative Extension, *Preserving Food: Processing Jams and Jellies* (FDNS-E-37-1), revised June 2011. https://openscholar.uga.edu/record/23661/files/FDNS-E-37-1.pdf
6. Christian, K. and Barefoot, S., National Center for Home Food Preservation, UGA and Clemson Cooperative Extension, *PUT IT UP! Method 2: Making Jam (Advanced)*, revised April 2015. https://newt.fcs.uga.edu/nchfp/putitup/Method%202%20-%20Making%20Jam%202015rev.pdf
7. U.S. Department of Agriculture and National Center for Home Food Preservation, *Complete Guide to Home Canning, Guide 7: Preparing and Canning Jams and Jellies*, revised July 2015, pp. 7-6 to 7-7. https://nchfp.uga.edu/papers/guide/GUIDE07_HomeCan_rev0715.pdf
8. McCarty, K., University of Maine Cooperative Extension, *5 Tips for Making Delicious Jam and Jelly This Summer*, June 26, 2025. https://extension.umaine.edu/food-health/2025/06/26/jam-and-jelly-tips/
9. Arnon, R., Henley, S.C. and Schwan, C.L., University of Georgia Extension, *Pectin for Home Food Preservation* (Circular 1373), December 11, 2025. https://fieldreport.caes.uga.edu/publications/C1373/pectin-for-home-food-preservation/
10. Zepp, M., Penn State Extension, *Preventing Jam and Jelly from Not Setting* (video), undated, accessed October 2026. https://extension.psu.edu/preventing-jam-and-jelly-from-not-setting
11. National Center for Home Food Preservation, *Testing Jelly without Added Pectin*, adapted from *So Easy to Preserve*, 6th ed. (2014), revised by Andress and Harrison. https://nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/testing-jelly-without-added-pectin
12. National Center for Home Food Preservation, UGA and Clemson Cooperative Extension, *PUT IT UP! Poster 2 (Advanced): Canning Jam*, 2015. https://newt.fcs.uga.edu/nchfp/putitup/Poster%202%20Advanced%20(Canning%20Jam).pdf
13. Kleine, H. and Botzet, C., South Dakota State University Extension, *A Guide to Water Bath Canning* (P-00255), 2022. https://extension.sdstate.edu/sites/default/files/2022-10/P-00255-v2.pdf
14. Kraft Heinz, *SURE.JELL Double-Batch Strawberry Jam* (recipe 500400), updated June 30, 2026. https://www.kraftheinz.com/sure-jell/recipes/500400-sure-jell-double-batch-strawberry-jam