Can you can jam in any glass jar, or only canning jars?
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Use Mason-type canning jars with two-piece lids for any jam you process in a canner. They are what the tested processing times were developed in, and USDA calls regular and wide-mouth canning jars with self-sealing lids "the best choice" [1][2]. A store-bought jar that takes a standard two-piece lid, such as some mayonnaise jars, can work for jam but fails and breaks more often; a jar that cannot take a two-piece lid is not recommended at all [1]. Plastic belongs in the freezer and the refrigerator, not the canner. This page sorts the jars people ask about and explains which jam processing times cover which sizes.
Why the tested times need canning jars
A processing time is only proven for the conditions it was tested under. Clemson Extension notes that standard canning jars have consistent shapes and volumes, which affects how heat moves into the food, and that processing times were developed for standard canning jars [2]. Canning jars are also made for the job: Clemson reports that jar breakage is rare when Mason jars are used properly [2], and NCHFP says they can be reused many times with only new lids [1].
Other glass may look just as sturdy and still fail in three ways: the glass is thinner or less tempered and cracks in the canner, the sealing surface is narrower and fails to seal, or the mouth will not take a lid that vents and seals the way the tested process assumed [1][2].
Jar by jar
| Jar | For canned jam? | What the sources say |
|---|---|---|
| Mason-type canning jar, regular mouth (about 2 3/8 in opening) or wide mouth (about 3 in) | Yes | The recommended jar; reuse with new lids [1] |
| Decorator jelly jars sold by canning-jar makers (8 and 12 oz) | Yes, with their two-piece lids | Listed among home canning jars by USDA [1] |
| Mayonnaise or salad dressing jar that takes a new two-piece canning lid | Possible, not advised | Expect more seal failures and breakage: narrower sealing surface, less tempering, and wear from utensils [1][2] |
| Pasta sauce or other jar labeled "Mason" | Check the size | Some are not a full standard size, and Cornell advises processing them for the next standard size up [3]; for jam that can mean a size with no tested time |
| Any commercial jar whose mouth cannot take a two-piece canning lid | No | Not recommended for home canning [1][2] |
| Bail-top (wire clamp) jars with glass lids and rubber gaskets, such as Weck-style jars | No tested process | Clemson: no science-based recommendations exist for canning in Weck jars or other glass-lid, gasket and clamp jars [2] |
| Old jars with zinc caps or glass lids | No | Not recommended [3] |
| Jars with one-piece lug or screw caps (common on jam you buy) | Not for home canning | These go with commercial processes; see jars and lids for jam you sell |
| Plastic jars and tubs | No for canning; yes for freezer and refrigerator jam | See below |
Reused jars from the grocery store
Washing a commercial jar does not make it a canning jar. Those jars were filled once at a factory on a process designed around that jar and its cap. If a store jar takes a standard two-piece canning lid, USDA allows it for acid foods such as jam, with the warning that you "should expect more seal failures and jar breakage" [1]. Put that against the cost of the batch it holds. For gifts and for keeping jam in the refrigerator, store jars are fine.
European and decorative jars
Weck, Le Parfait and similar jars are made to a high standard and are popular for presentation. The trouble is the closure: glass lids with rubber rings and clips were never part of the US research, so there is no US tested time for them [2]. If you want to use them, keep the jam in the refrigerator or freezer, or use them for jam you are serving soon. UK-style jam jars with twist-off caps fall into the same category; British recipes using them rely on methods covered on paraffin, inverting jars and other old methods.
Jar sizes the processing times cover
| Size | Covered by jam and jelly times? | Notes |
|---|---|---|
| Half-pint (8 oz) | Yes | USDA times are for half-pints or pints [4] |
| Pint (16 oz) | Yes | Same time as half-pints in USDA jam and jelly recipes [4] |
| 12 oz decorator jar | Between two tested sizes with the same time | Using the half-pint and pint time is a reasonable reading, not a separately tested one; confirm with your recipe's source |
| 4 oz jelly jar | Not listed in USDA jam recipes | Use only where your recipe's source gives a time for it; see squeeze bottles and mini jars |
| 1 1/2 pint and quart | No | Not covered by USDA jam times [4] |
| Half-gallon | No | USDA allows half-gallon jars only for very acid juices [1] |
How long to process each covered size, with altitude, is on how long to process jam. Which sizes sell, and what each holds by weight, is on jar sizes and fill weights.
Before each use: checking a jar
- Look at the rim. Run a fingertip around it. NCHFP names cracked or nicked jars among the common reasons a lid fails to seal [5].
- Look through the glass. Small scratches can cause cracking in the canner [1]. Cornell notes that a jar which stays cloudy after soaking in vinegar water may have etching or utensil scratches and is more likely to crack [3].
- Wash it. Wash in hot soapy water or a dishwasher and rinse [6]. Washing cleans but does not sterilize; whether you also need to sterilize depends on your processing time, explained on do you need to sterilize jars.
A jar that fails any of these checks can still hold dry goods, pens or flowers.
Where plastic belongs
There is no tested process for canning jam in plastic, so plastic stays out of the canner. It is a good choice in two places:
- Freezer jam. NCSU Extension's freezer jam directions call for freezer containers or canning jars, with 1/2 inch of headspace [7]. Plastic freezer containers do not crack when the jam expands.
- Refrigerator jam. Small cooked batches kept cold and eaten within weeks can go in any clean, food-grade container with a lid. See refrigerator jam.
If you are thinking of selling jam in squeeze bottles or plastic tubs, those formats need a commercial process and are covered on squeeze bottles and mini jars.
Choosing the lid for the jar
Every jar recommended above is used with a two-piece canning lid: a new flat lid every time and a reusable band. How to prepare lids, how tight to turn the band, and why the flat cannot be reused are on lids and bands.
References
- National Center for Home Food Preservation, Recommended Jars and Lids (from USDA Complete Guide to Home Canning, Agriculture Information Bulletin 539, revised 2015), viewed October 2026. https://nchfp.uga.edu/how/can/general-information/recommended-jars-and-lids/
- Clemson Cooperative Extension, Home and Garden Information Center, Barefoot, Why Mason-type Canning Jars, April 14, 2023. https://hgic.clemson.edu/why-mason-type-canning-jars/
- Cornell Cooperative Extension of Saratoga County, Whitten, Jars and Lids for Canning, undated, viewed October 2026. https://monroe.cce.cornell.edu/resources/jars-lids-for-canning
- USDA and National Center for Home Food Preservation, Complete Guide to Home Canning, Guide 7: Preparing and Canning Jams and Jellies, revised July 2015. https://nchfp.uga.edu/papers/guide/GUIDE07_HomeCan_rev0715.pdf
- National Center for Home Food Preservation, May canned food be reprocessed if the lid does not seal?, undated, viewed October 2026. https://nchfp.uga.edu/newsflash/may-canned-food-be-reprocessed-if-the-lid-does-not-seal
- National Center for Home Food Preservation, Do I need to pre-sterilize my jars before canning?, May 21, 2014. https://nchfp.uga.edu/blog/do-i-need-to-pre-sterilize-my-jars-before-canning
- N.C. Cooperative Extension, Sampson County Center, Knowles, Freezer Jam, June 13, 2022. https://sampson.ces.ncsu.edu/news/freezer-jam/
