Thermos Food Jar Sizing Guide: 12 oz vs. 17 oz: Which One Do You Need?

Choose the 12 oz thermos food jar for young children and small portions, and the 17 oz food jar for adults and full meals. To decide, measure your usual hot lunch in a measuring cup. Up to one cup fits the 12 oz. More than one cup needs the 17 oz. Size up if your portion sits right at one cup.

Key Takeaways

• The 17 oz holds 500 ml against 350 ml for the 12 oz, and stands one inch taller.

• Both jars share a 3.5-inch diameter, heat rating, and regular price, so capacity is the deciding spec.

• For mixed-age households, the 17 oz is the safer buy because it handles small portions too.

• The 17 oz handles hot soups and stews, with a silicone-sealed lid and wide mouth.

• Preheat with boiling water, and reheat food outside the jar, which is not microwave or oven safe.

Thermos Size Comparison: 12 Oz Vs 17 Oz At A Glance

Both jars share a 3.5-inch diameter, so the 17 oz gets its extra five ounces, about two-thirds of a cup, entirely from an extra inch of height. Ecozoi gives both jars the same rating, up to 12 hours hot or 24 hours cold, so capacity decides it.

A note on the labels: the ounces here measure volume, matching the millilitre figures. They don't tell you how heavy the food is.

Price won't settle the question either. Ecozoi lists both at the same regular price, $41.45 as of this writing.

Read more: How to Clean a Thermos Food Jar: Mold & Odor Removal Guide

The 12 Oz Thermos: Built For Small Appetites

It is recommended that the 12 oz jar be used for young children and small snacks. The 12 oz product page calls it an ideal portion for full meals or snacks. Both descriptions point the same way. It's the small jar.

At about one and a half cups, a thermos 12 oz jar holds a full cup of oatmeal or soup with room at the top. It stands 4.5 inches tall, an inch shorter than the 17 oz, which matters if the jar rides in a side pocket.

The 17 Oz Thermos Steel Jar: The Full-Meal Size

The 17 oz holds 500 ml, a little over two cups. It is a customer favorite with 48 5-star ratings, and it gives adults enough room for work lunches and hearty meals such as pasta or rice.

Extra volume changes what you pack. With the 12 oz, you pack a side. With the 17 oz, you pack the main course, like a full portion of pasta or a bowl of stew. Ecozoi's own use cases include oatmeal at your desk in the morning and stir-fry at lunch, no microwave needed.

Kids use it too. If you're buying one jar for a family with mixed ages, the 17 oz is the safer buy. A large jar holds a small portion, while a small jar has no room for a large one.

What Fits In Each Jar

Ecozoi's collection page lists everyday uses for its jars. Sorted by volume, they split like this.

For the 12 oz jar:

• A cup of soup beside a sandwich

• Oatmeal or porridge for a small breakfast

• Yogurt or a smoothie, both rated for cold

For the 17 oz jar:

• Pasta or rice as a full lunch

• Stew or hot soup for a winter hike

• Mac and cheese or dal-chawal for a hungry child

Soup shows up on both lists. Portion, not the type of food, picks the size.

Best Thermos For Hot Food School Lunch: Measure The Portion, Not The Age

Age is a weak guide to how much a child eats. A measuring cup gives you a number. Try this tonight with leftovers from dinner:

1. Spoon the hot food you'd pack for lunch into a measuring cup.
2. Read the volume. Count only what your child usually finishes, not what you hope for.
3. Up to one cup goes in the 12 oz. More than one cup goes in the 17 oz.
4. If your number sits right at one cup, size up.

Sizing up costs you one inch of height. Both jars share a diameter and a regular price. Sizing down costs you a second purchase if your child outgrows the small jar.

Before the first school day, hand your child the empty jar and let them open it. Our product pages say a lid should be tight but easy to open, especially for children. Both jars close with a leak-proof lid, so the backpack stays dry either way.

A wrong guess is fixable. Ecozoi accepts returns within 30 days of receipt.

Preheat The Jar, Whatever Size You Pick

We advise filling the jar with boiling water before you add food. Do it while the food heats on the stove, then empty the jar right before you pack.

Heat the food itself outside the jar. Ecozoi's product FAQ warns of insulation damage from direct heat or microwaves. Warm the food in a pot or a microwave-safe bowl, then pour it in.

Small Eaters Get The 12 Oz, Everyone Else Gets The 17 Oz

If your measuring cup says more than one cup, buy the 17 oz and stop second-guessing. If it says less, the 12 oz keeps lunch simple and the jar compact. Either way, measure one real lunch before you order. It takes one spoon and one measuring cup.

Both sizes ship with a spork and an organic cotton lunch bag, so nothing else needs to go in the cart. Here are the 12 oz jar and 17 oz jar once your number is in.

Ecozoi Stainless Steel Thermos Food Jars In 12 Oz And 17 Oz

We at Ecozoi list two vacuum-insulated stainless steel food jars: a 12 oz model and a 17 oz model. Both use 18/8 stainless steel with double-wall insulation and a wide mouth, and each includes a spork and an organic cotton lunch bag. The 12 oz jar measures about 4.5 by 3.5 inches, and the 17 oz jar about 5.5 by 3.5 inches. 

FAQs

1. What size food thermos should I get?

Get the 12 oz for young children and snack-sized portions. Get the 17 oz for adults and older children with big appetites. Buying one jar for a household with mixed ages? The 17 oz covers more eaters.

2. What sizes of Thermos food jars are available?

Ecozoi offers two Thermos food jar sizes, 12 oz (350 ml) and 17 oz (500 ml). The 12 oz jar is suited for smaller portions, snacks, or kids’ meals, while the 17 oz jar holds a larger serving for everyday lunches and meals.

3. Is the 12 oz thermos suitable for adults, or is it primarily for children?

We recommend it for young children and small snacks, but nothing stops an adult from buying it. A cup of soup next to a sandwich fits with room to spare. A full main dish doesn't fit, so choose the 17 oz.

4. How do I determine which size thermos food jar to buy?

Run the measuring cup test above. Then measure the bag pocket where the jar will ride, since the 17 oz stands 5.5 inches tall. If the jar has to fit a cup holder, check the space against the 3.5-inch diameter.

5. Can I use a 17 oz thermos food jar for hot soups and stews?

Yes. We promote the 17 oz for soups and stews, and the lid seals with a silicone ring to stop leaks. The wide mouth makes the jar easy to fill and clean. Preheat it with boiling water first, and reheat the food in a separate pot or bowl.