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    KitchenLunch BoxMonbento MB Square Bento Lunch Box
    #4 of 7
    Monbento MB Square Bento Lunch Box

    Key Specs

    Body / Tray Material

    PP (polypropylene)

    Gasket / Seal Material

    Food-grade silicone (removable)

    Total Capacity

    1.7L / 57 fl oz (2 × 28 fl oz + 10.5 fl oz food cup)

    Compartments

    2 stackable containers + 1 food cup

    Monbento

    Monbento MB Square Bento Lunch Box

    #4 of 7 lunch boxs tested

    5.8R3 Score / 10
    There are better options — here's why.
    Safety
    5.248% weight
    Usability
    6.530% weight
    Efficacy
    6.322% weight

    $34.95

    Buy on Amazon

    The bottom line

    What the product listing won't tell you

    Know before you buy

    The Monbento MB Square is the only truly leakproof bento box per America's Test Kitchen, with independent LFGB/FDA certification from TÜV and SGS labs — but the PP plastic body will permanently stain within the first school year, PFAS-free status is never disclosed, and the elastic band opening requires adult assistance for preschoolers.

    Buy it if

    • Leak-proof performance for sauces, dressings, and juicy fruits is your top priority — this is ATK's only confirmed leakproof pick in the category.

    Monbento MB Square Bento Lunch Box

    Monbento

    Monbento MB Square Bento Lunch Box

    $34.95
    Buy on Amazon
    Monbento MB Square Bento Lunch Box

    Monbento

    Monbento MB Square Bento Lunch Box

    $34.95Buy on Amazon

    We may earn a commission. It doesn't affect our scores.

  1. You need LFGB and FDA certification from independent labs — TÜV and SGS verification is confirmed.

  2. Your child is in grades K and up and can manage a two-step open mechanism independently.

  3. Volume over variety works for your lunches — 57 fl oz across two compartments handles adult and older-child portions.

  4. Lightweight matters — at 1.06 lbs, it's meaningfully lighter than stainless alternatives of comparable volume.

    5. Skip if

    • PFAS-free confirmation is a requirement — Monbento doesn't disclose PFAS-free status anywhere.

    • You're packing for a preschooler or kindergartener who needs to open their lunch independently — the elastic band plus lid mechanism consistently challenges ages 3-5.

    • You can't tolerate permanent staining — PP polypropylene will be orange-tinged from tomato sauce within weeks of daily use.

    • You need 3 or more food compartments for variety — two main containers limit how many food groups you can separate cleanly.

    Safety research

    Safety standards and ingredients related to Monbento MB Square Bento Lunch Box

    Ingredients avoided
    ingredients
    Microplastics from Heated Plastics- Microscopic plastic particles smaller than 5mm (microplastics) and smaller than 1 micrometer (nanoplastics) that shed from plastic components when repeatedly heated. Recent studies show heated plastics release millions of micro- and nanoplastic particles per gram. These particles have been found in human blood, placenta, and breast milk, and can carry other chemicals like phthalates and BPA as they leach into food and air.
    ingredients
    Melamine- An organic compound used to make hard, heat-resistant plastic (melamine resin). Found in cheap air fryer accessories, dishes, and utensils. Leaches formaldehyde when heated above 160 degrees F (70 degrees C). Not safe for high-heat cooking. Associated with kidney damage and the 2008 Chinese milk contamination scandal.
    ingredients
    Phthalates- A group of plasticizer chemicals used to make plastics flexible and durable. Found in PVC, vinyl, food packaging, personal care products, and kitchen appliance components. Phthalates are endocrine disruptors that affect testosterone and thyroid hormones, with strong evidence linking them to reproductive harm, particularly in developing boys.
    ingredients
    BPS (Bisphenol S)- A common replacement for BPA found in thermal receipt paper, plastics, and food containers. BPS binds to estrogen receptors at similar potency to BPA and has been detected in 81% of Americans tested. Many products labeled BPA-free contain BPS instead.
    Standards met
    standards
    FDA Food Contact Rules (21 CFR)- The U.S. regulatory framework governing every material that can touch your food - from nonstick coatings on air fryer baskets to plastic containers, packaging films, and can linings. Codified in Title 21 of the Code of Federal Regulations (21 CFR), Parts 170-199, these rules define which substances are permitted in food contact applications, what migration limits apply, and how manufacturers prove compliance. Critically, FDA does not pre-approve finished cookware - meaning that "FDA compliant" on a product label is a manufacturer's self-declaration, not a government stamp of approval.
    concepts
    Endocrine Disruption- A broad category of chemical interference in which synthetic substances mimic, block, or interfere with the body's hormone signaling system. Endocrine-disrupting chemicals (EDCs) -- including BPA, phthalates, PFAS, parabens, and flame retardants -- trigger biological effects at extraordinarily low doses, with some of the most concerning effects occurring at levels far below conventional toxicology thresholds. The WHO and Endocrine Society have identified EDCs as a global health threat, with particular concern for fetal development, reproductive function, metabolism, and cancer risk.

    Every term is independently researched and sourced.

    Full Safety Dictionary

    What's inside

    Specs the product listing doesn't explain

    Performance

    What determines how well this performs its core job

    Total Capacity1.7L / 57 fl oz (2 × 28 fl oz + 10.5 fl oz food cup)
    Safety & Materials

    What your food and family come into contact with every use

    Body / Tray MaterialPP (polypropylene)
    Gasket / Seal MaterialFood-grade silicone (removable)
    Dishwasher SafeYes — all components; remove silicone seals before washing
    CertificationsLFGB, FDA 21 CFR (TÜV + SGS verified)
    PFAS-FreeNot disclosed
    Living With It

    Noise, maintenance, and what happens if something goes wrong

    Warranty3 years
    Price (observed)$34.95
    Other Specs

    Additional product details

    Compartments2 stackable containers + 1 food cup
    Dimensions14 × 14 × 14 cm (5.5 × 5.5 × 5.5 in)
    Weight (empty)1.06 lbs (480g)
    Closure MechanismElastic bands (elastane) + pop-off intermediate lids
    Leak-ProofYes — each container individually silicone-sealed
    Microwave SafeYes — containers only, 500W max, 3 min max
    Chemical SafetyBPA-free (verified), BPS-free (brand claim), phthalate-free (brand claim)
    Replacement PartsYes — seals, bands, lids, food cups via monbento.com
    Recommended AgeAges 6+ / adults (not preschool-designed)
    Made InFrance

    How we scored it

    7 criteria — open any layer to see exactly what we found

    5.2

    Safety

    Below Average

    6.3

    Efficacy

    Fair

    6.5

    Usability

    Fair

    Food Contact Material SafetyCritical
    31%
    5.2▾

    Criteria

    Body / Tray Material
    4/10

    The containers are polypropylene — lightweight and microwave-safe, but the same type of plastic that permanently stains and can leach additives into acidic or warm food. BPA-free is confirmed, but that doesn't cover all chemical concerns.

    Lid & Gasket / Seal Material
    8/10

    The silicone seals are the best-in-class gasket material — chemically inert, no leaching. Remove and dry them after every wash or mold grows in the crevices. That's a 30-second daily step, not optional.

    Chemical Safety Disclosure
    4/10

    BPA-free is lab-verified. BPS-free and phthalate-free are brand declarations without independent confirmation. PFAS-free is never mentioned — a meaningful gap for families in states actively banning PFAS in food contact materials.

    R3 verdict

    The MB Square containers are made of polypropylene — FDA-approved, BPA-free, and LFGB/FDA certified via independent labs. That's meaningful regulatory compliance.

    But PP plastic is a daily food-contact surface for children that can leach chemical additives under acidic, fatty, or warm food conditions. Monbento's BPA-free status is independently verified; BPS-free and phthalate-free are brand claims; PFAS-free is never disclosed.

    Third-Party Certification & VerificationCritical
    17%
    4▾

    Criteria

    Third-Party Safety Certifications
    4/10

    LFGB and FDA compliance, both independently verified by TÜV and SGS — solid regulatory coverage. What's missing is a PFAS-specific independent lab test. You're getting validated food-contact safety against regulatory standards, not cutting-edge clean-label certification.

    R3 verdict

    Monbento holds LFGB (German food safety standard) and FDA 21 CFR compliance — both confirmed by independent labs TÜV and SGS. That's a real regulatory foundation, not just brand self-declaration.

    The gap is the absence of T1 certification: no NSF cert, no independent PFAS/heavy metal ICP-MS lab test, no Mamavation approval. LFGB and FDA validate food-contact safety broadly but don't specifically test for the full PFAS spectrum.

    Moderate confidence
    Seal & PortabilityCritical
    12%
    7.1▾

    Criteria

    Leak-Proof Performance
    8/10

    Each container seals independently — sauce in the bottom, dry food on top, nothing migrates. America's Test Kitchen called it the only truly leakproof bento in their test. Two seal systems to clean every day, but zero leaks during transport.

    Compartment Design & Capacity
    6/10

    Two deep containers plus a small sauce cup. Great volume for a full adult meal or older child's lunch — but a sandwich fills one entire container, leaving everything else for the second. If you pack more than two food types, expect them to share space.

    R3 verdict

    Child-FriendlinessImportant
    17%
    6.2▾

    Criteria

    Ease of Opening for Children
    5/10

    Opening requires two steps: slip off the elastic band, then pop open the container lid. Ages 5 and up typically manage this independently. Ages 3-4 will need help, especially with the elastic band grip. Not a kindergarten-first-day-independent design.

    Empty Weight
    8/10

    At 1.06 lbs empty, this adds minimal weight to a school backpack. A comparable stainless steel lunch box would weigh 1.3-1.7 lbs for the same volume. The lighter weight is a real, daily advantage for children carrying full backpacks.

    R3 verdict

    At 1.06 lbs empty, the MB Square is light for its volume class — a meaningful advantage over stainless alternatives that typically run 1.3-1.7 lbs. The opening mechanism is the constraint: elastic band removal plus lid pop-off is a two-step sequence that ages 6+ handle independently but ages 3-5 consistently struggle with. This is an adult-and-older-child lunch box sized and designed accordingly — 57 fl oz is substantial for younger children who may only eat half of what fits.

    Cleaning & MaintenanceImportant
    14%
    5.8▾

    Criteria

    Ease of Cleaning
    8/10

    Everything goes in the dishwasher. Pull out the silicone seals first and dry them separately — skip that step and mold grows in the crevice within a few weeks. A 30-second step each evening, but not optional.

    Stain & Odor Resistance
    3/10

    Pack tomato pasta or berries a few times and the containers will carry that orange tint permanently. Curry and fish odors embed into PP and can transfer to fresh food. Baking soda treatment reduces odor but doesn't reverse staining. This is PP's fundamental limitation — not a defect.

    R3 verdict

    Durability & LongevityImportant
    10%
    3.9▾

    Criteria

    Material Durability
    3/10

    Expect permanent tomato-sauce staining and curry odor retention within the first school year. PP warps from repeated dishwasher heat cycles over time. Plan on a replacement at 2 years for daily-use school boxes.

    Warranty Coverage
    6/10

    Three years of warranty coverage is above average for plastic lunch boxes. Replacement seals and bands are sold on the Monbento site, so you can service the box rather than replace it entirely. Keep your proof of purchase.

    R3 verdict

    The MB Square offers a 3-year warranty — better than the 1-year industry floor — and replacement parts are sold on the Monbento website. That extends the serviceability window.

    Price EfficiencyNice to have
    0%
    8▾

    Criteria

    Price per R3 Point
    8/10

    At $34.95 with certified leak-proof performance and LFGB/FDA lab verification, the price is genuinely strong for what you get. The PP material limits the score ceiling — but if you're shopping for value in a certified bento box, this competes well.

    R3 verdict

    At $34.95, the MB Square delivers the category's strongest confirmed leak-proof performance plus LFGB/FDA independent certification at a price well below premium alternatives. The $0.52/R3-point ratio represents strong value.

    If you can accept PP plastic trade-offs, this is competitive category value. The estimated cost-per-year is $11.65/yr based on a 3-year material lifespan.

    Moderate confidence
    Read the full methodology

    How we scored it

    7 criteria — open any layer to see exactly what we found

    5.2

    Safety

    Below Average

    6.3

    Efficacy

    Fair

    6.5

    Usability

    Fair

    Food Contact Material SafetyCritical
    31%
    5.2▾

    Criteria

    Body / Tray Material
    4/10

    The containers are polypropylene — lightweight and microwave-safe, but the same type of plastic that permanently stains and can leach additives into acidic or warm food. BPA-free is confirmed, but that doesn't cover all chemical concerns.

    Lid & Gasket / Seal Material
    8/10

    The silicone seals are the best-in-class gasket material — chemically inert, no leaching. Remove and dry them after every wash or mold grows in the crevices. That's a 30-second daily step, not optional.

    Chemical Safety Disclosure
    4/10

    BPA-free is lab-verified. BPS-free and phthalate-free are brand declarations without independent confirmation. PFAS-free is never mentioned — a meaningful gap for families in states actively banning PFAS in food contact materials.

    R3 verdict

    The MB Square containers are made of polypropylene — FDA-approved, BPA-free, and LFGB/FDA certified via independent labs. That's meaningful regulatory compliance.

    But PP plastic is a daily food-contact surface for children that can leach chemical additives under acidic, fatty, or warm food conditions. Monbento's BPA-free status is independently verified; BPS-free and phthalate-free are brand claims; PFAS-free is never disclosed.

    Third-Party Certification & VerificationCritical
    17%
    4▾

    Criteria

    Third-Party Safety Certifications
    4/10

    LFGB and FDA compliance, both independently verified by TÜV and SGS — solid regulatory coverage. What's missing is a PFAS-specific independent lab test. You're getting validated food-contact safety against regulatory standards, not cutting-edge clean-label certification.

    R3 verdict

    Monbento holds LFGB (German food safety standard) and FDA 21 CFR compliance — both confirmed by independent labs TÜV and SGS. That's a real regulatory foundation, not just brand self-declaration.

    The gap is the absence of T1 certification: no NSF cert, no independent PFAS/heavy metal ICP-MS lab test, no Mamavation approval. LFGB and FDA validate food-contact safety broadly but don't specifically test for the full PFAS spectrum.

    Moderate confidence
    Seal & PortabilityCritical
    12%
    7.1▾

    Criteria

    Leak-Proof Performance
    8/10

    Each container seals independently — sauce in the bottom, dry food on top, nothing migrates. America's Test Kitchen called it the only truly leakproof bento in their test. Two seal systems to clean every day, but zero leaks during transport.

    Compartment Design & Capacity
    6/10

    Two deep containers plus a small sauce cup. Great volume for a full adult meal or older child's lunch — but a sandwich fills one entire container, leaving everything else for the second. If you pack more than two food types, expect them to share space.

    R3 verdict

    Child-FriendlinessImportant
    17%
    6.2▾

    Criteria

    Ease of Opening for Children
    5/10

    Opening requires two steps: slip off the elastic band, then pop open the container lid. Ages 5 and up typically manage this independently. Ages 3-4 will need help, especially with the elastic band grip. Not a kindergarten-first-day-independent design.

    Empty Weight
    8/10

    At 1.06 lbs empty, this adds minimal weight to a school backpack. A comparable stainless steel lunch box would weigh 1.3-1.7 lbs for the same volume. The lighter weight is a real, daily advantage for children carrying full backpacks.

    R3 verdict

    At 1.06 lbs empty, the MB Square is light for its volume class — a meaningful advantage over stainless alternatives that typically run 1.3-1.7 lbs. The opening mechanism is the constraint: elastic band removal plus lid pop-off is a two-step sequence that ages 6+ handle independently but ages 3-5 consistently struggle with. This is an adult-and-older-child lunch box sized and designed accordingly — 57 fl oz is substantial for younger children who may only eat half of what fits.

    Cleaning & MaintenanceImportant
    14%
    5.8▾

    Criteria

    Ease of Cleaning
    8/10

    Everything goes in the dishwasher. Pull out the silicone seals first and dry them separately — skip that step and mold grows in the crevice within a few weeks. A 30-second step each evening, but not optional.

    Stain & Odor Resistance
    3/10

    Pack tomato pasta or berries a few times and the containers will carry that orange tint permanently. Curry and fish odors embed into PP and can transfer to fresh food. Baking soda treatment reduces odor but doesn't reverse staining. This is PP's fundamental limitation — not a defect.

    R3 verdict

    Durability & LongevityImportant
    10%
    3.9▾

    Criteria

    Material Durability
    3/10

    Expect permanent tomato-sauce staining and curry odor retention within the first school year. PP warps from repeated dishwasher heat cycles over time. Plan on a replacement at 2 years for daily-use school boxes.

    Warranty Coverage
    6/10

    Three years of warranty coverage is above average for plastic lunch boxes. Replacement seals and bands are sold on the Monbento site, so you can service the box rather than replace it entirely. Keep your proof of purchase.

    R3 verdict

    The MB Square offers a 3-year warranty — better than the 1-year industry floor — and replacement parts are sold on the Monbento website. That extends the serviceability window.

    Price EfficiencyNice to have
    0%
    8▾

    Criteria

    Price per R3 Point
    8/10

    At $34.95 with certified leak-proof performance and LFGB/FDA lab verification, the price is genuinely strong for what you get. The PP material limits the score ceiling — but if you're shopping for value in a certified bento box, this competes well.

    R3 verdict

    At $34.95, the MB Square delivers the category's strongest confirmed leak-proof performance plus LFGB/FDA independent certification at a price well below premium alternatives. The $0.52/R3-point ratio represents strong value.

    If you can accept PP plastic trade-offs, this is competitive category value. The estimated cost-per-year is $11.65/yr based on a 3-year material lifespan.

    Moderate confidence
    Read the full methodology
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    Where to buy

    Verified retailer — current pricing

    Starting price

    $34.95

    R3 approved retailer Score unaffected by purchase
    Buy on Amazon

    We earn a small commission on purchases. It never influences our scores — R3 is funded by readers, not brands.

    Other Options to Consider

    Alternatives that address specific trade-offs

    Why this matters: The MB Square offers a 3-year warranty — better than the 1-year industry floor — and replacement parts are sold on the Monbento website. That extends

    PlanetBox Rover Stainless Steel Bento Lunch Box
    Better durability & longevity

    PlanetBox Rover Stainless Steel Bento Lunch Box

    PlanetBox

    8.0$69.28

    Scores 9.4/10 on durability & longevity vs 3.9 here

    LunchBots Large Cinco Stainless Steel Lunch Container
    Better durability & longevity

    LunchBots Large Cinco Stainless Steel Lunch Container

    LunchBots

    7.2$34.99

    Scores 10.0/10 on durability & longevity vs 3.9 here

    Yumbox Original Leakproof Bento Lunch Box
    Better durability & longevity

    Yumbox Original Leakproof Bento Lunch Box

    Yumbox

    6.2$32.99

    Scores 4.4/10 on durability & longevity vs 3.9 here

    ECOlunchbox Three-in-One Stainless Steel Bento Box
    Better durability & longevity

    ECOlunchbox Three-in-One Stainless Steel Bento Box

    ECOlunchbox

    5.8$24.95

    Scores 6.5/10 on durability & longevity vs 3.9 here

    Didn't find the lunch box you need?

    See all lunch boxs we reviewed

    #4 of 7 lunch boxs reviewed

    standards
    CPSC Compliance / General Certificate of Conformity- The U.S. Consumer Product Safety Commission sets mandatory safety standards for consumer products. A General Certificate of Conformity (GCC) is a written self-certification manufacturers issue for general-use products. For children's products, a stricter Children's Product Certificate (CPC) is required, backed by independent third-party lab testing. Neither certificate guarantees a product was actually tested correctly - but they do establish legal accountability.
    concepts
    BPA-Free Label Claim- A marketing label indicating a product does not contain bisphenol A (BPA). While it guarantees the absence of one specific chemical, it does not mean the product is free of other bisphenols -- most notably BPS and BPF, which are structurally related substitutes with comparable estrogen-mimicking properties. 'BPA-free' is a starting point, not a safety certification.
    ASIN
    B00GRZINNS
    Active Prop 65 WarningNone found

    The silicone seals score well — food-grade silicone is chemically inert and an appropriate gasket material for daily use.

    The silicone seals score well — food-grade silicone is chemically inert and an appropriate gasket material for daily use.

    Moderate confidence
    Moderate confidence

    Leak-proof performance is the MB Square's standout strength. America's Test Kitchen rated it the only truly leakproof bento box in their category test — a direct result of the individual silicone-sealed intermediate lids on each stackable container.

    Leak-proof performance is the MB Square's standout strength. America's Test Kitchen rated it the only truly leakproof bento box in their category test — a direct result of the individual silicone-sealed intermediate lids on each stackable container.

    The trade-off is two-compartment architecture: 57 fl oz total volume is generous but you can only cleanly separate two food types. Families packing three or more food groups will need a third container.

    The trade-off is two-compartment architecture: 57 fl oz total volume is generous but you can only cleanly separate two food types. Families packing three or more food groups will need a third container.

    Moderate confidence
    Moderate confidence
    Moderate confidence
    Moderate confidence

    The MB Square is fully dishwasher-safe — all components, including the PP containers, PBT lid, and food cup go in the dishwasher daily. The one mandatory step is removing and drying the silicone seals before washing, or mold grows in the seal-to-lid crevice.

    The MB Square is fully dishwasher-safe — all components, including the PP containers, PBT lid, and food cup go in the dishwasher daily. The one mandatory step is removing and drying the silicone seals before washing, or mold grows in the seal-to-lid crevice.

    That's the daily maintenance ask. The harder limitation is PP's porosity: polypropylene absorbs pigments and odors permanently, so tomato sauce stains and curry smells become part of the box's identity within the first school year.

    That's the daily maintenance ask. The harder limitation is PP's porosity: polypropylene absorbs pigments and odors permanently, so tomato sauce stains and curry smells become part of the box's identity within the first school year.

    Moderate confidence
    Moderate confidence

    But the PP material itself tells a different story: polypropylene is the lunch box plastic with the shortest useful lifespan, typically 1-3 years before permanent staining, odor absorption, and dishwasher warping make replacement the practical choice. The warranty covers defects; it doesn't prevent the material from aging.

    But the PP material itself tells a different story: polypropylene is the lunch box plastic with the shortest useful lifespan, typically 1-3 years before permanent staining, odor absorption, and dishwasher warping make replacement the practical choice. The warranty covers defects; it doesn't prevent the material from aging.

    Moderate confidence
    Moderate confidence