Mason 6 7: Complete Guide to This Classic Mason Jar Size

The mason 6 7 jar is one of those kitchen staples that has been around so long, most people never stop to think about what those numbers actually mean. If you have ever stood in the canning aisle wondering whether a “6 7” jar will hold your grandmother’s tomato sauce recipe, you are not alone. This guide breaks down exactly what the mason 6 7 size refers to, how it compares to other jar sizes, and when it is the right choice for your kitchen projects.

⚡Quick Answer: A mason 6 7 jar refers to a jar with a 6.7 ounce capacity, which is a smaller size commonly used for jams, jellies, baby food, and single-serving preserves. The “6 7” notation comes from older labeling conventions that listed capacity in fluid ounces.

What Does Mason 6 7 Actually Mean?

The numbering on mason jars has confused home canners for generations. The “6 7” designation is not a model number or a style code. It refers to the jar’s liquid capacity of 6.7 fluid ounces, or approximately 200 milliliters.

This size sits in the “quarter pint” category in most canning charts, though it is slightly smaller than a true quarter pint, which measures 4 ounces. The 6.7 ounce jar is sometimes called a “jelly jar” or a “mini mason” in retail listings.

The naming convention traces back to early 20th century glass manufacturers who stamped capacity directly into the mold. A jar marked “6 7” simply told buyers it held 6 and 7/10 ounces. Today, brands like Ball and Kerr still produce this size, though modern packaging often lists it as “6.7 oz” or “200 ml” instead of the older “6 7” format.

Key point: When you see “mason 6 7” in a recipe or a vintage canning guide, it means the smaller jelly jar, not a standard half pint or pint.

Mason 6 7 vs Other Common Jar Sizes

Understanding where the mason 6 7 fits in the jar size lineup helps you pick the right container for each project. Here is how it compares:

Jar Size	Capacity (oz)	Capacity (ml)	Best Uses
Mason 6 7	6.7 oz	200 ml	Jams, jellies, baby food, gifts
Quarter Pint	4 oz	118 ml	Single servings, spices, samples
Half Pint	8 oz	237 ml	Jams, jellies, small batch canning
Pint	16 oz	473 ml	Salsas, pickles, sauces
Quart	32 oz	946 ml	Whole fruits, tomatoes, large batches

The mason 6 7 sits in a sweet spot between the tiny 4 ounce jar and the more common 8 ounce half pint. It holds enough for a generous serving of jam or a small batch of pickled vegetables without committing to a larger container you might not finish.

💡Pro Tip: If you are buying jars for wedding favors or holiday gifts, the mason 6 7 size is ideal. It looks substantial in a gift basket but does not require you to make enormous batches of whatever you are canning.

Best Uses for the Mason 6 7 Jar

This jar size earned its place in kitchens for specific reasons. Here are the applications where it genuinely shines:

Small Batch Canning

When you are working with a limited harvest, the mason 6 7 jar lets you can smaller quantities without wasting space or ingredients. A single strawberry plant might yield just enough for three or four of these jars, whereas a half pint batch would leave you with half filled containers.

Homemade Baby Food

Parents who make their own baby food appreciate the 6.7 ounce capacity because it matches typical infant meal portions. The jars are also easy to sterilize and stack neatly in the refrigerator.

Gift Giving and Party Favors

The mason 6 7 has become a favorite for event planners and home bakers. Filled with layered cookie mixes, homemade hot chocolate powder, or small batch preserves, these jars look polished with a ribbon tied around the neck.

Spice and Dry Good Storage

For pantry organization, the 6.7 ounce jar holds roughly 1 cup of dry goods like dried herbs, tea leaves, or homemade spice blends. The wide mouth versions are easier to scoop from than narrow necked spice jars.

Candle Making and Crafts

Beyond food, the mason 6 7 jar is popular in the DIY community for small candles, bath salts, and homemade beauty products. The heat resistant glass handles melted wax without cracking.

How to Choose Between Wide Mouth and Regular Mouth

Mason jars come in two opening styles, and the mason 6 7 is available in both. Your choice affects how you use the jar.

Regular mouth jars have an opening of about 2.75 inches in diameter. They work fine for liquids and small pieces but can be awkward when you are trying to pack whole fruits or chunky relishes.

Wide mouth jars open to about 3.38 inches. That extra room makes filling and emptying much easier, especially for thicker preserves or anything you need to scoop out with a spoon.

For the mason 6 7 size specifically, the wide mouth version is often preferred for baby food and gift jars because it is easier to clean thoroughly. The regular mouth works well for jams and jellies that pour or spoon out easily.

💡Pro Tip: Check your canning funnel before buying. Standard canning funnels fit regular mouth jars, but you need a wide mouth funnel for the larger opening. Nothing is more frustrating than discovering this mid batch.

Canning Safety and Processing Times for Mason 6 7 Jars

Smaller jars process faster than larger ones, which is one reason the mason 6 7 is popular for high acid foods like jams and pickles.

According to the National Center for Home Food Preservation, processing times for 6 to 8 ounce jars in a boiling water bath typically run 5 to 10 minutes for high acid foods at sea level, depending on the specific recipe. That is roughly half the time required for quart jars.

However, the processing time is not the only safety consideration:

• Always use new lids for canning. The sealing compound on used lids will not form a reliable seal.
• Leave the correct headspace, usually 1/4 inch for jams and jellies in this jar size.
• Adjust processing times for altitude. At elevations above 1,000 feet, you need to add time.
• Do not overtighten the bands. Finger tight is the standard, allowing air to escape during processing.

The smaller volume of the mason 6 7 means the contents reach the required internal temperature faster, which helps preserve texture and color in delicate foods.

Where to Buy Mason 6 7 Jars and What to Expect to Pay

The mason 6 7 jar is widely available, though it is less common than the half pint and pint sizes. You will find them at:

• Grocery and big box stores during canning season (roughly May through September in most regions)
• Hardware stores with seasonal canning sections
• Online retailers including Amazon, Walmart, and specialty canning suppliers year round
• Thrift stores and estate sales for vintage versions with the original “6 7” mold marks

Pricing varies by quantity and brand. A typical 12 pack of 6.7 ounce jars from Ball or Kerr runs between $10 and $15, which works out to roughly $1 per jar. Vintage jars with the old style “6 7” marking can command higher prices from collectors, especially if they are in unusual colors like cobalt blue or amber.

💡Pro Tip: Buy jars in the off season. Retailers discount canning supplies heavily in late fall, and you can often find the mason 6 7 size at 30 to 50 percent off.

Key Takeaways

• The mason 6 7 jar holds 6.7 fluid ounces or about 200 milliliters
• It is ideal for jams, jellies, baby food, gifts, and small batch canning
• Processing times are shorter than larger jars, typically 5 to 10 minutes for high acid foods
• Available in both regular mouth and wide mouth versions
• Expect to pay $10 to $15 per dozen for new jars, with better deals in the off season

Frequently Asked Questions About Mason 6 7 Jars

Q: What does the 6 7 mean on a mason jar?
A: The “6 7” marking on a mason jar indicates its capacity of 6.7 fluid ounces, or approximately 200 milliliters. This was a common way for early glass manufacturers to mark jar volume directly in the mold.

Q: Is a mason 6 7 jar the same as a quarter pint?
A: No. A true quarter pint jar holds 4 ounces, while the mason 6 7 holds 6.7 ounces. The mason 6 7 is sometimes grouped with quarter pints in canning charts because both are considered small jars, but they are not the same size.

Q: Can I use mason 6 7 jars for pressure canning?
A: Yes, mason 6 7 jars can be used for pressure canning low acid foods like vegetables and meats. However, you must follow the processing times and pressures specified for that jar size in a tested recipe from a reliable source like the National Center for Home Food Preservation.

Q: Are mason 6 7 jars freezer safe?
A: Mason 6 7 jars are freezer safe if you leave adequate headspace, typically at least 1 inch, to allow for expansion. Wide mouth versions are safer for freezing because the contents can expand upward more easily without stressing the glass.

Q: Do mason 6 7 jars come in colors other than clear?
A: Yes. Vintage mason 6 7 jars were produced in blue, green, and amber glass, and these colored versions are popular with collectors. Modern production is mostly clear glass, though some limited edition colored jars are released occasionally.

Q: What size lids fit mason 6 7 jars?
A: Mason 6 7 jars use the same standard lids as other mason jars. Regular mouth jars take 70mm lids, and wide mouth jars take 86mm lids. This standardization means you can use the same lid stock across your entire jar collection.

Q: How many mason 6 7 jars do I need for a batch of jam?
A: A standard jam recipe using 4 cups of fruit and 4 cups of sugar typically yields about 5 to 6 cups of finished jam. That fills roughly 6 to 8 mason 6 7 jars, depending on how much the jam reduces during cooking.

Q: Can I microwave mason 6 7 jars?
A: Mason jars are made from soda lime glass, which is generally microwave safe for reheating. However, you should remove the metal lid and band first, and avoid subjecting a cold jar to sudden high heat, which can cause thermal shock and cracking.

References & Further Reading

1. National Center for Home Food Preservation: General Canning Information
2. Ball Canning: Jar Size Guide and Processing Times
3. USDA Complete Guide to Home Canning: Guide 01, Principles of Home Canning
4. The Spruce Eats: Mason Jar Sizes and Uses

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About This Article

This guide was researched and written by a home canning enthusiast with over a decade of hands on experience preserving food in mason jars of every size. The information on processing times and safety comes from the National Center for Home Food Preservation and USDA guidelines, not from personal experimentation. Always consult current, tested recipes when canning at home.