Can You Freeze Mason Jars? The Safe Option’s Cost

Yes, you can freeze Mason jars when the manufacturer identifies the jar as freezer-safe: Ball’s current guides approve straight or tapered sides, require ½ inch of headspace in a pint jar, and specify a 0°F freezer; cool the food before packing, keep the jar upright and unstacked until frozen, and never use a shouldered jar for liquid.

I learned while making four hundred food-memory recordings that the practical detail often survives after the meal itself has gone hazy. Someone forgets the soup, then remembers who carried the jar home. Freezing in glass deserves the same attention to the awkward detail. The safe option gives up capacity, demands a cooling step, and occupies more shelf space. Those costs are real. A split jar costs the food and leaves glass in the freezer.

Which Mason jars are actually freezer-safe?

Choose by the manufacturer’s stated use and the jar’s profile, rather than by the Mason name. Ball’s jar-selection guide says straight-sided and tapered jars are suitable for freezing; shouldered jars are intended for shelf storage. Its current size chart identifies regular-mouth jars in 4-, 8-, and 12-ounce sizes and wide-mouth jars in 16- and 24-ounce sizes as freezer-safe. The same chart omits that designation from its 16- and 32-ounce regular-mouth jars and its 32-ounce wide-mouth jar.

For soup, my clearest default is Ball model 66000ZFP, the wide-mouth pint. Ball’s product page gives it a 16-ounce capacity and explicitly marks it freezer-safe. KaTom’s catalog specification for that exact model reports a 3.38-inch diameter and a 5-inch height. The wide opening and nearly straight wall leave no inward shelf above the food where an expanding frozen mass can become trapped.

The 24-ounce wide-mouth Ball jar is also listed as freezer-safe, so the pint is not the only sound choice. I still prefer the 16-ounce jar for a single meal: it chills faster than one large portion, fits a saucepan after thawing, and limits the amount lost if a jar already has an unseen flaw. Ball does not publish a single-jar diameter for the 24-ounce option on the chart I consulted, so I would not invent one to make the comparison look tidier.

How does a straight-sided freezer jar compare with a shouldered canning jar?

A shouldered jar narrows between its full body and its mouth. The Ball regular-mouth quart provides a measurable example. Fillmore Container’s catalog entry for model 62000 gives the 32-ounce jar an outside diameter of 4.13 inches. Mason Jar Lifestyle’s mouth-size guide gives a regular-mouth jar an outer mouth diameter of 2¾ inches. Across the shoulder, that profile contracts by about 1.38 inches in diameter.

The straight-sided freezer jar costs capacity in this comparison: 16 ounces for Ball model 66000ZFP versus 32 ounces for the shouldered model 62000. What you buy with that smaller vessel is a clear upward route for expansion. Ball assigns the 16-ounce wide-mouth jar to freezer use and the shouldered quart to canning and shelf storage. A jar’s thick glass, intact lid, or history of surviving the freezer cannot reverse its geometry.

That distinction matters most with a continuous liquid mass. The U.S. Geological Survey reports that the density of ice is about 9 percent lower than the density of liquid water. The same mass therefore needs more volume as it freezes. In a straight or outward-tapered jar, expansion can move toward the open headspace. An inward shoulder puts rigid glass over the rising food.

How much headspace should you leave in a Mason jar?

Leave ½ inch between soup and the rim of a freezer-safe pint jar. That is Ball’s manufacturer fill instruction for rigid freezer containers and for the freezer-safe jars in its selection guide. If your jar has an embossed freeze-fill line, treat it as the maximum fill level; when there is no line, measure ½ inch from the rim. The nominal 16-ounce capacity is therefore larger than the usable frozen-soup fill.

The National Center for Home Food Preservation gives more detailed headspace by pack and opening. Its table distinguishes liquid food from dry-packed food and pint jars from quart jars:

| Food and container | Headspace required by NCHFP | | --- | ---: | | Liquid pack, wide-top pint | ½ inch | | Liquid pack, wide-top quart | 1 inch | | Liquid pack, narrow-top pint | ¾ inch | | Liquid pack, narrow-top quart | 1½ inches | | Dry pack, pint with either opening | ½ inch | | Dry pack, quart with either opening | ½ inch |

For a Ball wide-mouth pint of soup, the agency table and the manufacturer’s rule meet at ½ inch. A quart of liquid needs 1 inch under the NCHFP table, yet Ball’s current 32-ounce jars are absent from its freezer-safe list. More headspace does not turn a shouldered or unapproved jar into a freezer jar.

Do liquid soup and solid leftovers expand the same way?

Liquid soup deserves the liquid-pack rule because it settles into one continuous body against the glass. Solid leftovers contain gaps and vary widely in water content. USDA FoodData Central’s SR Legacy data give prepared canned chicken noodle soup a gram weight of 248 grams per cup, while cooked long-grain white rice weighs 158 grams per cup. Using NIST’s conversion of one U.S. cup to 236.5882 milliliters, those portion densities are about 1.05 and 0.67 grams per milliliter, respectively.

Density alone does not predict the precise expansion of a recipe. A loose cup of rice has air between grains; a thick risotto, gravy-covered casserole, or bean stew behaves more like a semi-liquid pack. Water content, dissolved salt and sugar, suspended pieces, and trapped air all change the freezing behavior. The defensible kitchen rule is based on how the food occupies the jar: food that levels and flows gets liquid headspace.

NCHFP says most foods need headspace, then names exceptions such as loose-packed asparagus and broccoli, tray-packed foods, bony meat pieces, and bread. Those exceptions can shift within available air instead of forming a solid plug against every wall. A compacted “solid” leftover has lost that advantage. Give packed rice, mashed potatoes, and dense casseroles the ½ inch that NCHFP specifies for dry packs.

How do you freeze food in Mason jars without thermal shock?

Cool the food before it enters the jar. NCHFP’s packaging guidance says to cool foods and syrups before packaging because cooling speeds freezing and protects color, flavor, and texture. USDA’s Food Safety and Inspection Service says a refrigerator should hold 40°F or below, and a large pot of soup or stew should be divided into small portions in shallow containers. Refrigerate perishable food within 2 hours; do not wait on the counter for the whole pot to become cold.

I use 40°F as the fill temperature for this method. It gives a home cook a measurable threshold and avoids moving a hot jar straight into a 0°F freezer. Yes, it means washing the shallow cooling container as well as the Mason jar. That extra dish is part of what the safer option costs.

1. Inspect a manufacturer-approved freezer jar for chips, hairline cracks, and a damaged rim. Retire any doubtful jar from food storage.
2. Divide the cooked food into shallow containers, refrigerate it within the USDA’s 2-hour limit, and wait until a clean food thermometer reads 40°F or below.
3. Transfer the chilled food into the room-temperature jar. Stop ½ inch below the rim for a Ball wide-mouth pint of soup, or follow the greater headspace specified for your approved container and food.
4. Wipe the rim, center a clean lid, apply the band loosely, and label the jar with the food and packing date.
5. Set the jar upright in a single layer near the coldest part of a 0°F freezer. Ball says to stack jars only after the food is completely frozen.
6. Tighten the band after freezing if needed. Thaw the jar in the refrigerator, then transfer the food to cookware for reheating.

Which lids work on Mason jars in the freezer?

Metal Mason-jar lids and bands can go into the freezer with an approved jar. Ball’s own freezer-jam directions center the lid, apply the band loosely, freeze the jar, and adjust the band to fingertip-tight after the contents are frozen. Freezing is storage, so the lid does not need the vacuum seal required for shelf-stable canning.

Loose at first does not mean unsecured. The lid should remain centered, the jar should stay upright, and the rim should be clean. A one-piece plastic freezer lid may be more convenient for repeated opening, but it does nothing to make a shouldered jar safe. Lid material cannot compensate for the wrong glass profile or missing headspace.

What does the safe option cost in everyday use?

The first cost is food capacity. A 16-ounce jar cannot be filled with 16 fluid ounces of soup and still preserve the manufacturer’s ½-inch expansion space. The second is container count: the same batch occupies more small jars than one 32-ounce quart, although the quart’s shouldered geometry excludes it from this job under Ball’s guide.

Cooling adds handling. Soup moves from pot to shallow container, reaches 40°F or below in the refrigerator, and only then enters the jar. Freezer organization changes too. Each jar stands upright in a single layer until solid; stacking comes later.

I would pay those costs. The alternative asks an old canning jar to withstand pressure in the precise place where its body narrows. No remembered success changes the current manufacturer record: freezer-safe shape, measured headspace, cooled food, and a 0°F freezer.

Frequently asked questions

Can all Mason jars go in the freezer?

No. Use only jars the manufacturer identifies as freezer-safe. Ball’s current guide approves straight-sided or tapered shapes and excludes shouldered jars from freezer use. Its freezer-safe list includes wide-mouth 16- and 24-ounce jars, while current 32-ounce regular- and wide-mouth jars lack that designation. Inspect every jar before filling.

Why can’t you freeze Mason jars with shoulders?

A shoulder narrows above the jar body and leaves rigid glass over the food. USGS says ice is about 9 percent less dense than liquid water, so the same mass requires more space when frozen. Straight or tapered walls let expansion move upward into headspace; a shoulder obstructs that route and raises breakage risk.

How much space should I leave in a Mason jar for freezing?

For a freezer-safe Ball wide-mouth pint, leave ½ inch between the food and rim. NCHFP also specifies ½ inch for a liquid-packed wide-top pint, 1 inch for a wide-top quart, and ½ inch for dry packs. Use the greater requirement whenever your approved container’s manufacturer gives a larger allowance.

Can Mason jars with metal lids be frozen?

Yes. Ball’s freezer-jam instructions place the metal lid on the jar, apply the band loosely, and tighten it after the contents freeze. Keep the jar upright and the rim clean. The lid does not make an unsuitable jar safe; the glass still needs a freezer-approved straight or tapered profile and correct headspace.

Can I put hot soup in a Mason jar and freeze it?

Cool the soup before packaging. NCHFP directs cooks to cool food before placing it in freezer containers. USDA says to divide a large pot into small, shallow containers, refrigerate perishable food within 2 hours, and hold the refrigerator at 40°F or below. Transfer the chilled soup to a room-temperature freezer-safe jar.

How do you thaw frozen food in a Mason jar?

Move the upright jar from the freezer to the refrigerator and let the food thaw gradually. Ball’s freezer-jam directions use refrigerator thawing. Once the contents release, transfer them to suitable cookware for reheating. Discard food from a cracked jar, since tiny glass fragments cannot be reliably separated from soup or other leftovers.