Quick answer
Choose the 28oz for all-day hydration on long trips or sports practices; pick the 18oz for everyday school use and smaller hands.
Capacity and portability trade-off
The 28oz holds about 55% more water than the 18oz, meaning fewer refills during long outings. However, the 28oz is taller and heavier when full, which may be less convenient for younger kids or for fitting into standard backpack side pockets.
Both bottles share the same 100% plastic-free construction and MadeSafe® certification, so your choice comes down to how much water your child needs to carry and how far they'll be from a refill station.
Trade-offs at a glance
- 28oz – More capacity, heavier: Holds 28oz of water, ideal for all-day hikes, sports tournaments, or long car rides. The extra weight when full may be noticeable for younger kids. Best for older kids (10+) or teens who need maximum hydration without frequent refills.
- 18oz – Lighter, easier to carry: Holds 18oz of water, sufficient for a school day or short practice. The lighter weight and smaller size fit standard backpack pockets and smaller hands. Best for children ages 8–10 or for everyday use where refills are available.
- Both are 100% plastic-free and MadeSafe® certified: No plastic touches the water, and the medical-grade silicone sport top is safe for active use. Both are top-rack dishwasher safe for easy cleaning. Health and safety are identical; your decision is purely about capacity and portability.
Product facts at a glance
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Big Mouth® Sport 28oz Bottle: 100% Plastic-Free: The bottle, sleeve, collar, and sport top all contain zero plastic. MadeSafe® Certified. You get a completely plastic-free hydration solution that meets rigorous health and environmental standards, ideal for parents avoiding plastic exposure.
Big Mouth® Sport 28oz Bottle
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Big Mouth® Sport 18oz Bottle: 18/8 Food Service-Grade Stainless Steel Bottle: Single-wall construction that's lightweight, shatter-proof, lead-free, and top-rack dishwasher safe. The single-wall design makes the 18oz lighter and easier for smaller children to carry, while still being durable and easy to clean.
Big Mouth® Sport 18oz Bottle
Which bottle fits your child?
Best for
- Older kids (10+) and teens who need maximum hydration on long outings or sports practices – choose the 28oz.
- Everyday school use, shorter activities, or smaller children (ages 8–10) – choose the 18oz.
Not for
- Toddlers or children under 8 – consider the Pura Sport Mini 11oz instead.
- Parents who want a vacuum-insulated bottle – these are single-wall, so they won't keep drinks cold for hours.
