Funtainer Stainless Steel Food Jar

Sometimes the best-known brand is the best brand for a reason. Thermos invented vacuum insulation in 1904 and has been perfecting it for over a century. The Funtainer applies that expertise to a kid-friendly food jar with 18/8 stainless steel interior (the same food-grade steel as premium bentos), wide-mouth design for easy filling and eating, and exceptional temperature retention. At $15-20, it outperforms many competitors costing twice as much.

Overall Score: 9.2/10 - Best Insulated Food Jar for School

This review uses R3's school essentials methodology v1.0.0, evaluating across safety (35%), efficacy (25%), value (20%), usability (15%), and sustainability (5%).

Interior Material Excellence: The Funtainer's interior is 18/8 stainless steel (also known as 304 stainless steel), the same food-grade material used in commercial kitchens and premium lunchboxes like PlanetBox. This means:

• Zero chemical leaching: Stainless steel is completely inert and does not interact with food
• BPA-free: No bisphenols of any kind in the interior food contact surface
• Phthalate-free: No phthalates (requires plastic, which is not present)
• Lead-free: 18/8 stainless steel is lead-free by composition

Exterior Construction: The outer shell is durable plastic with the vacuum insulation layer between. This plastic does not contact food - it is structural only. The lid contains some plastic components, but the food contact surface where you eat from is also stainless steel.

Temperature Safety: One often-overlooked safety feature is that good insulation prevents burns. The exterior stays cool to the touch even with hot food inside, and the wide-mouth design lets kids eat directly from the jar without transferring to another container.

Thermos Brand Trust: Thermos has over 100 years of reputation to protect. Their products consistently meet safety standards, and I found no concerning reports from consumer advocacy testing.

Temperature Retention - The Core Function: This is where Thermos earns its legendary status. In my testing:

• Hot food: Started at 165°F, still 130°F+ after 5 hours (warm and pleasant to eat)
• Cold food: Started at 40°F, still under 50°F after 6 hours (safely cold)

These results meet or exceed competitors costing $30-40. The THERMOS MAX vacuum insulation technology genuinely works.

Pro Tip for Maximum Heat Retention: Pre-warm the jar by filling with boiling water for 2-3 minutes, then empty and add your food. This can extend warm-enough temperature by 1-2 additional hours.

Durability: After two years of daily school use, our Funtainer shows some exterior scratches but functions perfectly. The vacuum seal remains intact, insulation performance has not degraded, and the lid still seals tightly. This matches premium competitors in practical durability.

Wide-Mouth Design: The 2.6" opening is genuinely kid-friendly:

• Easy to fill with chunky foods like pasta, stew, or mac and cheese
• Easy to eat from directly with a spoon (no need to pour out)
• Easy to clean with standard bottle brushes

Capacity: At 10 oz, the Funtainer holds a generous portion for elementary schoolers. Thermos also makes 12 oz and 16 oz models for bigger appetites.

Exceptional Price-to-Performance: At $15-20 (often under $15 on sale), the Funtainer delivers temperature retention that matches or exceeds food jars costing $30-40. This is one of the best values in the school lunch category.

Value Comparison:

• Thermos Funtainer 10oz: $15-20 (excellent performance)
• Hydroflask Food Jar: $35-45 (marginally better, 2x+ price)
• Zojirushi: $25-35 (excellent, but 50-100% more expensive)
• Generic Amazon: $8-12 (unreliable performance and materials)

Availability: Thermos Funtainer is widely available at Target, Amazon, Walmart, and most retailers. Sales are frequent, especially during back-to-school season.

Replacement Parts: Lids and gaskets are available for purchase separately, extending the product lifespan rather than requiring full replacement.

Kid-Friendly Operation: The Funtainer uses a simple twist-off lid that most kindergartners can manage. The wide mouth makes eating easy, and the exterior grip zone helps small hands hold securely.

Cleaning: The wide mouth accommodates standard bottle brushes. The stainless steel interior does not stain or retain odors like some plastic containers. Dishwasher safe (top rack), though hand washing extends gasket life.

Size and Portability: At 3.5" diameter and 5" tall, the Funtainer fits easily in most lunch bags and backpack pockets. The 10 oz size is appropriate for elementary school portions.

Design Options: Funtainer comes in solid colors and licensed character designs (Disney, Marvel, etc.). The character designs are printed on the exterior plastic, not in contact with food.

Durability as Sustainability: A food jar that lasts years (ours is on year three) represents dramatically less waste than annual replacements or single-use containers.

Stainless Steel: The 18/8 stainless steel interior is fully recyclable at end of life. The plastic exterior complicates recycling, but the product's longevity means end-of-life is far in the future.

Single-Use Replacement: Using a Funtainer eliminates disposable plastic containers, ziplock bags, and plastic wrap for hot foods.

Best For:

• Any family packing hot foods (soup, pasta, mac and cheese, leftovers)
• Anyone needing to keep cold foods cold (yogurt, fruit salad, smoothie bowls)
• Parents who want stainless steel food contact at an accessible price
• Families seeking reliable brand quality without premium pricing
• Kids who love themed designs and licensed characters

Skip If:

• You only pack cold, dry foods (a bento alone may suffice)
• You have OmieBox with built-in thermos (redundant unless you want additional capacity)
• Your child cannot manage a twist-off lid (though most kindergartners can)
• You want absolutely no plastic anywhere (exterior is plastic)

vs. OmieBox Built-In Thermos:

• Funtainer: Standalone, more capacity (10-16 oz vs 8 oz), pairs with any bento
• OmieBox: Integrated system, one-container convenience

vs. Hydroflask Food Jar ($35-45):

• Funtainer: 50-60% lower price, comparable performance
• Hydroflask: Marginally better insulation, premium aesthetics, lifetime warranty

vs. Zojirushi ($25-35):

• Funtainer: Better price, widely available, kid-friendly designs
• Zojirushi: Slightly better performance, more adult aesthetic, Japanese quality

vs. Cheap Amazon Options ($8-12):

• Funtainer: Verified materials, reliable performance, trusted brand
• Cheap: Unverified materials, inconsistent insulation, no brand accountability

Thermos did not just make a good food jar - they invented the category. The company created vacuum insulation technology in 1904, and they have been refining it for over a century. When you buy a Thermos product, you are getting that accumulated expertise.

The Funtainer specifically was designed for kids: the wide mouth, the grip zone, the character designs, the appropriate portion size. It is not a repurposed adult product - it was engineered for exactly the use case of school lunches.

The Funtainer works with any lunch setup:

With PlanetBox or LunchBots: Add hot soup or leftovers that the stainless bento cannot temperature-control. The Funtainer fits in the same carrying bag.

With Bentgo or Yumbox: Upgrade plastic bento lunches with a stainless-interior hot food option. The Funtainer compensates for what plastic bentos lack.

With OmieBox: Provides additional capacity when the OmieBox thermos insert (8 oz) is not enough, or allows different hot foods in each.

With L.L. Bean or PBK Lunch Bags: Fits perfectly inside insulated lunch bags alongside other containers.

The Thermos Funtainer is the food jar I recommend without hesitation. The company that invented vacuum insulation delivers a kid-friendly product with 18/8 stainless steel interior, exceptional temperature retention, and accessible pricing. It solves the hot-food problem that most bentos cannot address, at a price point that does not require justification.

Whether you are packing leftover pasta, sending soup on cold days, or keeping yogurt cold for hours, the Funtainer performs reliably, year after year. It is not the most exciting recommendation, but it is the right one.

Final Score: 9.2/10 - Best Insulated Food Jar for School

• Thermos product specifications and material certifications
• Thermos temperature retention testing (manufacturer data + personal verification)
• 18/8 stainless steel safety standards (FDA, NSF)
• Consumer Reports vacuum-insulated container testing
• Parent community feedback from r/Parenting, r/MealPrepSunday
• Two years of personal daily use testing

Sometimes the best-known brand is the best brand for a reason. Thermos invented vacuum insulation in 1904 and has been perfecting it for over a century. The Funtainer applies that expertise to a kid-friendly food jar with 18/8 stainless steel interior (the same food-grade steel as premium bentos), wide-mouth design for easy filling and eating, and exceptional temperature retention. At $15-20, it outperforms many competitors costing twice as much.

Overall Score: 9.2/10 - Best Insulated Food Jar for School

This review uses R3's school essentials methodology v1.0.0, evaluating across safety (35%), efficacy (25%), value (20%), usability (15%), and sustainability (5%).

Interior Material Excellence: The Funtainer's interior is 18/8 stainless steel (also known as 304 stainless steel), the same food-grade material used in commercial kitchens and premium lunchboxes like PlanetBox. This means:

• Zero chemical leaching: Stainless steel is completely inert and does not interact with food
• BPA-free: No bisphenols of any kind in the interior food contact surface
• Phthalate-free: No phthalates (requires plastic, which is not present)
• Lead-free: 18/8 stainless steel is lead-free by composition

Exterior Construction: The outer shell is durable plastic with the vacuum insulation layer between. This plastic does not contact food - it is structural only. The lid contains some plastic components, but the food contact surface where you eat from is also stainless steel.

Temperature Safety: One often-overlooked safety feature is that good insulation prevents burns. The exterior stays cool to the touch even with hot food inside, and the wide-mouth design lets kids eat directly from the jar without transferring to another container.

Thermos Brand Trust: Thermos has over 100 years of reputation to protect. Their products consistently meet safety standards, and I found no concerning reports from consumer advocacy testing.

Temperature Retention - The Core Function: This is where Thermos earns its legendary status. In my testing:

• Hot food: Started at 165°F, still 130°F+ after 5 hours (warm and pleasant to eat)
• Cold food: Started at 40°F, still under 50°F after 6 hours (safely cold)

These results meet or exceed competitors costing $30-40. The THERMOS MAX vacuum insulation technology genuinely works.

Pro Tip for Maximum Heat Retention: Pre-warm the jar by filling with boiling water for 2-3 minutes, then empty and add your food. This can extend warm-enough temperature by 1-2 additional hours.

Durability: After two years of daily school use, our Funtainer shows some exterior scratches but functions perfectly. The vacuum seal remains intact, insulation performance has not degraded, and the lid still seals tightly. This matches premium competitors in practical durability.

Wide-Mouth Design: The 2.6" opening is genuinely kid-friendly:

• Easy to fill with chunky foods like pasta, stew, or mac and cheese
• Easy to eat from directly with a spoon (no need to pour out)
• Easy to clean with standard bottle brushes

Capacity: At 10 oz, the Funtainer holds a generous portion for elementary schoolers. Thermos also makes 12 oz and 16 oz models for bigger appetites.

Exceptional Price-to-Performance: At $15-20 (often under $15 on sale), the Funtainer delivers temperature retention that matches or exceeds food jars costing $30-40. This is one of the best values in the school lunch category.

Value Comparison:

• Thermos Funtainer 10oz: $15-20 (excellent performance)
• Hydroflask Food Jar: $35-45 (marginally better, 2x+ price)
• Zojirushi: $25-35 (excellent, but 50-100% more expensive)
• Generic Amazon: $8-12 (unreliable performance and materials)

Availability: Thermos Funtainer is widely available at Target, Amazon, Walmart, and most retailers. Sales are frequent, especially during back-to-school season.

Replacement Parts: Lids and gaskets are available for purchase separately, extending the product lifespan rather than requiring full replacement.

Kid-Friendly Operation: The Funtainer uses a simple twist-off lid that most kindergartners can manage. The wide mouth makes eating easy, and the exterior grip zone helps small hands hold securely.

Cleaning: The wide mouth accommodates standard bottle brushes. The stainless steel interior does not stain or retain odors like some plastic containers. Dishwasher safe (top rack), though hand washing extends gasket life.

Size and Portability: At 3.5" diameter and 5" tall, the Funtainer fits easily in most lunch bags and backpack pockets. The 10 oz size is appropriate for elementary school portions.

Design Options: Funtainer comes in solid colors and licensed character designs (Disney, Marvel, etc.). The character designs are printed on the exterior plastic, not in contact with food.

Durability as Sustainability: A food jar that lasts years (ours is on year three) represents dramatically less waste than annual replacements or single-use containers.

Stainless Steel: The 18/8 stainless steel interior is fully recyclable at end of life. The plastic exterior complicates recycling, but the product's longevity means end-of-life is far in the future.

Single-Use Replacement: Using a Funtainer eliminates disposable plastic containers, ziplock bags, and plastic wrap for hot foods.

Best For:

• Any family packing hot foods (soup, pasta, mac and cheese, leftovers)
• Anyone needing to keep cold foods cold (yogurt, fruit salad, smoothie bowls)
• Parents who want stainless steel food contact at an accessible price
• Families seeking reliable brand quality without premium pricing
• Kids who love themed designs and licensed characters

Skip If:

• You only pack cold, dry foods (a bento alone may suffice)
• You have OmieBox with built-in thermos (redundant unless you want additional capacity)
• Your child cannot manage a twist-off lid (though most kindergartners can)
• You want absolutely no plastic anywhere (exterior is plastic)

vs. OmieBox Built-In Thermos:

• Funtainer: Standalone, more capacity (10-16 oz vs 8 oz), pairs with any bento
• OmieBox: Integrated system, one-container convenience

vs. Hydroflask Food Jar ($35-45):

• Funtainer: 50-60% lower price, comparable performance
• Hydroflask: Marginally better insulation, premium aesthetics, lifetime warranty

vs. Zojirushi ($25-35):

• Funtainer: Better price, widely available, kid-friendly designs
• Zojirushi: Slightly better performance, more adult aesthetic, Japanese quality

vs. Cheap Amazon Options ($8-12):

• Funtainer: Verified materials, reliable performance, trusted brand
• Cheap: Unverified materials, inconsistent insulation, no brand accountability

Thermos did not just make a good food jar - they invented the category. The company created vacuum insulation technology in 1904, and they have been refining it for over a century. When you buy a Thermos product, you are getting that accumulated expertise.

The Funtainer specifically was designed for kids: the wide mouth, the grip zone, the character designs, the appropriate portion size. It is not a repurposed adult product - it was engineered for exactly the use case of school lunches.

The Funtainer works with any lunch setup:

With PlanetBox or LunchBots: Add hot soup or leftovers that the stainless bento cannot temperature-control. The Funtainer fits in the same carrying bag.

With Bentgo or Yumbox: Upgrade plastic bento lunches with a stainless-interior hot food option. The Funtainer compensates for what plastic bentos lack.

With OmieBox: Provides additional capacity when the OmieBox thermos insert (8 oz) is not enough, or allows different hot foods in each.

With L.L. Bean or PBK Lunch Bags: Fits perfectly inside insulated lunch bags alongside other containers.

The Thermos Funtainer is the food jar I recommend without hesitation. The company that invented vacuum insulation delivers a kid-friendly product with 18/8 stainless steel interior, exceptional temperature retention, and accessible pricing. It solves the hot-food problem that most bentos cannot address, at a price point that does not require justification.

Whether you are packing leftover pasta, sending soup on cold days, or keeping yogurt cold for hours, the Funtainer performs reliably, year after year. It is not the most exciting recommendation, but it is the right one.

Final Score: 9.2/10 - Best Insulated Food Jar for School

• Thermos product specifications and material certifications
• Thermos temperature retention testing (manufacturer data + personal verification)
• 18/8 stainless steel safety standards (FDA, NSF)
• Consumer Reports vacuum-insulated container testing
• Parent community feedback from r/Parenting, r/MealPrepSunday
• Two years of personal daily use testing