Pressure Canner Load

Pressure canner and boxes of lidsIs there a minimum load limit or guidance on the number of jars one must have for pressure canning?

Guidance has been given by the USDA and National Center for Home Food Preservation (NCHFP) regarding the minimum physical size requirements to be considered a pressure canner: the device must be large enough to hold at least 4 quart jars standing upright on a rack with the lid secure for USDA and NCHFP published recipes and processes.  Pressure canners meeting the specifications come in various sizes with either a dial gauge or a weighted gauge.

A minimum load for a pressure canner has not been specified by the USDA or NCHFP.  In 2016, Ball canning issued guidance on a minimum pressure canner load stating, “To ensure proper pressure and temperature is achieved for safe processing, you must process at least 2 quart or 4 pint jars in the pressure canner at one time.”

At this time, the USDA, NCHFP, university extensions, and contacted pressure canner manufacturers have not endorsed or tested the Ball recommendation regarding the 2 quarts/4 pints load minimum for safety.  However, it may be a good practice.  The more jars there are in a pressure canner, the more space is filled and the quicker it will vent (and the less time the food in the jars will be subjected to heat).2  UCCE Master Food Preservers of El Dorado County (CA) have found that a very small canner load can be difficult to bring up to required pressure and risks the water in the canner running dry.  At any rate, canner load would have an effect on the warm-up and cool-down times, both of which are important to tested pressure canning processes.

When pressure canning a small batch, add jars of water (no lids necessary) to fill the canner space.  The added jars will also prevent jars with food content from tipping over.  Adding jars of water when water-bath or steam canning also helps with jars floating or tipping.

If you have canning questions, please do not hesitate to contact us by phone or e-mail. We are happy to help!

Sources:

1The All New Ball Book Of Canning And Preserving, 2016, page 274.

2Pressure Canner Minimum Loads, UCCE Master Food Preservers of El Dorado County, December 2023.

Updated January 2024, mg.

Marlene Geiger

I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.

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22 thoughts on “Pressure Canner Load

  1. i neeed to downsize to half pints . how many can go in a pressure cooker . i love canning but i really need to use smaller jars now

  2. The number of jars that fit in a canner will depend on how big the canner is that you have. When canning smaller jars you can stack them but would need to alternate them so they are not sitting on top of each other but half on one jar and half on another jar that is below. Remember unless there are specific times for canning half pints you would need to can the food for the pint jar time.

  3. I have two questions. The minimum load size shows quarts and pints. Can I assume that if I need to have four pints I would need to have eight half pints for a minimum load?
    Also, I heard somewhere that when using smaller jars such as the small quarter pint jars that you cannot fully submerse them in water. Does that mean I could not ever use the quarter pint jars since they’re shorter than my minimum water amount in my pressure canner unless they are a second layer over larger jars such as the 1/2 pint?

  4. Erin, thank you for your questions. The recommendation for load is for pressure canning. There are very few tested recipes that would have one pressure canning with half pints and pressure canning in quarter pints is unlikely. Quarter pints are usually used with hot water bath canning. As for load minimum, there needs to be adequate load in the canner for the proper heat up and cool down for safely processing. When the minimum cannot be met, one can can water. If you do not intend to keep the water, an old canning lid can be used.

  5. Thank you. I like to do my chicken and beef broth in a smaller containers since my recipes for dinners are only for two. That’s where the half and quarter pint size jars come into play for me it’s perfect sizing. And of course I process it at the full pint length for safety.

  6. I see the question about 1/4 pints was a little glossed over. There is an important use for pressure canning 1/4 pints and that is for roasted hot chiles. I would like some to be used like the little cans like you can buy in the stores, and a half pint of chiles would be wasted in many cases (not to mention would need a LOT of peppers to fill). So, the question remains, can you pressure can 1/4 pints and how would the water level be affected? Thank you so much for your time.

  7. Hi Tara, I totally understand your reasoning for wanting to process hot chilies in 1/4 pints. However, the bottom line is that we cannot advise you on this as there are NO tested recipes for doing so. Tested recipes only offer the option of pints or 1/2 pints for processing hot peppers/chilies which I am sure you are well aware of. Unless your canner specifies otherwise, you need 3 inches of water to properly process foods in a pressure canner.

  8. Marlene, thank you for the direct response, I actually didn’t know, which is why I was asking and pointed out the original 1/4 pint question was glossed over, as stated. But thank you again.

  9. I am wondering if I can water bath can only 4 quarts in my large canner? Will the tip without a full load? I don’t have anything to separate them and keep them from tipping in all that water? Thanks so much!

  10. Hi Deb, if your 4 qt jars are full, they should process just fine in a water bath canner without tipping. There are many times that I don’t have a full canner and haven’t had a problem with tipping. Thanks for your inquiry.

  11. I read different things about hoq much water must be in pressure canner. I haf 2 ” for 4 jars pumpkin. Is t hung at enough?

  12. Hi Elsie, it is always best to follow the directions that came with your canner; when that is not possible, you want 2-3 inches of water. If you are canning pumpkin, make sure that it is cubed. It is unsafe to can mashed or pureed pumpkin. Here are some links from the National Center for Home Food Preservation that will answer your questions.
    https://nchfp.uga.edu/tips/fall/pumpkins.html
    https://nchfp.uga.edu/how/can_04/pumpkin_winter_squash.html
    https://nchfp.uga.edu/publications/uga/using_press_canners.html

  13. Hi Amy, generally if you follow the USDA recommendations, the processing time remains the same. However, it is also very important to follow the directions that came with you canner.

  14. I had jars tip over while water bath canning. I processed less than a load and put the jars around the outside of the canner. The jars sealed, but is the food good? Should I throw them away? Your help would be appreciated! I scoured the web and can’t find the answer.

  15. Hi Angela, you do not say what you were canning but in all likely hood, the food is safe. You may have lost some liquid and if so, you will want to use those jars sooner rather than later. In the future, when you have a canner that is not full, place jars filled with water (lid is not necessary) in the canner to take up space. Another solution is to use a rack that is designed to hold jars. See this image: https://www.amazon.com/Norpro-604-Large-Canning-Rack/dp/B001E8QAAG/ref=sr_1_7?keywords=Canner+Rack&qid=1658150670&sr=8-7

  16. I have a question that I believe you can answer for me. I usually run a batch with 3-4 quart jars with 3 quarts of water in a 16-quart canner. This has worked well so far. However, last night I did a batch with twice as many jars, and steam and water were escaping through the air vent. Jars lost liquid, and the canner wouldn’t seal.
    Should I adjust the water level when I am running a batch with more jars? That would make sense.
    I am also still trying to find the perfect setting on my stove to allow the water to heat up at the appropriate rate. It started boiling rapidly, quicker than usual last night as well. I turned it down to a simmer, but the temp didn’t adjust for at least 15-20 minutes.
    Thanks for your help

  17. Hi Pamela, I wish that we could talk so I could find out more about what you are actually doing. As I read your questions, I have concerns about several things but perhaps it is because I don’t understand. I will address my concerns and hopefully in doing so, I will answer your questions.
    1) Water level in the canner. Follow the directions that came with your canner for the amount of water to put in the canner. Usually the amount is somewhere between 2 and 3 inches and the number of jars in the canner has no bearing on the amount of water. Adding more water may interfere with the process. There are acceptions when some specific products may require starting with more water in the canner. Always follow the USDA directions for specific foods requiring more water added to the canner.
    2) Appropriate boiling rate. It is important that you find a heat setting that does not cause rapid heat up and uneven heat during processing to assure that the product is safe. A rapid start up may actually cause the product to be under processed. Per the National Center for Home Food Preservation, a loaded pressure canner requires about 12 to 15 minutes of heating before it begins to vent; another 10 minutes to vent the canner; another 5 minutes to a pressurize the canner; another specified time per recipe to process the acid food; and, finally, another 20 to 60 minutes to cool the canner before removing jars. The timing should not be rushed.
    3) In 2016, Ball recommended that a minimum canner load should be 2 quart jars or 4 pint jars or a combination that equalled 2 quart jars. There are no USDA or extenion recommendations of such. It is fine to add jars of water to fill the canner. If jars of water are added, the jars should be lidded with either new or old flat lids–new if you want to keep the water, old lids if the water will be dumped.
    4) Steam escaping. Steam and sometimes a bit of a sputter of water should come from the vent pipe. However, there should be no steam or water escaping from around the lid during heat up or processing. If water or steam is escaping around the canner lid, the seal needs to be replaced. Steam or water escaping around the lid will result in underprocessing and water loss necessary to build and maintain steam.
    5) Water loss. It is normal for some water to be lost from the canner during processing, usually during venting. However, if the water loss is excessive and there is also loss of liquid from food being processed, it is likely due to rapid boiling inside the canner and/or excessive steam/water escaping from the canner during processing. A dial gauge canner should maintain a near constant pressure on the dial; the weights on a weighted gauge canner should rock gently.
    6) Start with hot water and jars. Jars, filled some water so they don’t float, can be warmed in the canner as the canner water heats. The canner water should be hot, but not boiling. The warmed jars are lifted from the hot water, water dumped, filled, air removed, lidded, and lifted back into the hot water for processing.

  18. I only canned 2 pints in pressure canner of chicke and they sealed so is it safe to eat. I just found out about minimum jars today after canning 2 3 or 4 at a time

  19. Hi Pauline, The advice on canner load comes from Ball in their 2016 canning book, The All New Ball Book of Canning and Preserving and supposedly applies to all of Ball’s pressure canning recipes. The rule would appear to be designed to help ensure that heat-up and cool-down times aren’t too short. No such guidance has been issued by the USDA, any Cooperative Extension, the National Center for Home Food Preservation, or canner manufacturer that I am aware of.

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