REASONS TO BUY
Consistent
Easy to use
Multiple settings
Reusable water
REASONS TO AVOID
Super slow heating
Didn't reach desired temperature
Kiinde Kozii Review
Expensive warmer with a basic design that warms consistently but doesn't get the contents warm enough on manufacturer settings
Credit: Abriah Wofford
RELATED: The Best Bottle Warmers
Our Verdict
The Kiinde Kozii is an average warmer from our best bottle warmers review. It is easy to use and has a single dial for heating adjustments, fewer parts to keep track of and a basic design. This warmer offers consistent temperatures across tests and the ability to reuse the water multiple times before replacing it. This could be useful if you use your warmer multiple times a day or for multiple babies. If you only use it sporadically, you probably don't want to leave water just sitting in the chamber. Unfortunately, this unit is more expensive than most, doesn't get milk to body temperature using manufacturer settings, and is harder to clean with a recommended bleach solution. Given the longer heating times and our desire to use it outside the guidelines to speed the process, we worry parents will push the limits, overheat bottle contents, and potentially hurt nutritional quality. While not a terrible warmer, it isn't a tester favorite, and we think there are better choices in our lineup.
Editor's Note: The Kozii is part of our new bottle warmer review that we tested in March 2024.
Compare to Similar Products
 This Product
Kiinde Kozii | |||||
|---|---|---|---|---|---|
| Awards |  Best Overall Bottle Warmer | Most Consistent Bottle Warmer |  Best Budget Bottle Warmer |  Best Travel Warmer | |
| Price | $75 List $64.99 at Amazon | $60 List $59.99 at Amazon | $80 List $64.99 at Amazon | $28 List | $80 List $79.99 at Amazon |
Overall Score  |
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| Star Rating | |||||
| Bottom Line | This expensive option doesn't warm contents enough on the recommended settings, but it is easy to use and consistent | A higher-price warmer that is easy to use and can heat consecutive bottles but it isn't very fast | A useful app and easy-to-use interface make this expensive warmer appealing | The lower price, features, and multiple settings are appealing | While not perfect, this option works well and is highly portable for those frequently away from home |
| Rating Categories | Kiinde Kozii | Chicco Digital & St... | Baby Brezza Safe an... | First Years Gentle... | Momcozy Portable Wa... |
| Health and Safety (35%) | |||||
| Warming Quality (25%) | |||||
| Warming Time (20%) | |||||
| Ease of Use (15%) | |||||
| Ease of Cleaning (5%) | |||||
| Specs | Kiinde Kozii | Chicco Digital & St... | Baby Brezza Safe an... | First Years Gentle... | Momcozy Portable Wa... |
| Heat Technology | Water Bath | Water Bath + Steam | Water Bath + Steam | Water Bath | Ceramic Heating Element |
| Max Temp | 122.3 °F | 92.2 °F | 105.9 °F | 88.4 °F | 118.9 °F |
| Frozen Capability | Yes | Yes | Yes | Yes | No |
| Baby Food Heating | Yes | Yes | Yes | Yes | No |
| Audible Beep | No | Yes | Yes | Yes | Yes |
| Measured Dimensions | 4.8 in x 6.2 in x 6.3 in | 5.2 in x 5.1 in x 12.4 in | 6.0 in x 6.6 in x 11.8 in | 5.2 in x 4.9 in x 10.3 in | 3.5 in x 3.5 in x 5.0 in |
| Contents Below 113ºF/45ºC | Yes | Yes | Yes | Yes | Yes |
| Time to Reach 80F | 7.5 min | 8.5 min | 5.5 min | 10.0 min | 6.0 min |
| Time to Reach 98F | N/A | N/A | 9.5 min | N/A | 10.0 min |
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Our Analysis and Test Results
The Kiinde company was founded by two MIT engineers (and dads) who envisioned an opportunity to improve infant feeding via a unique bottle warmer. From there, the lineup expanded to a complete system that includes the Kiinde Squeeze baby bottle whose Kiinde Twist Pouch hooks up to any breast pump via a variety of adapters for direct pump-to-pouch expression. The uniquely designed Kiinde Keeper accents the system with a freezer storage solution designed to avoid bag puncture.
Performance Comparison
If you push the Kozii to its limits to reach body temperature, it can end up going past the 104F temperature when nutritional aspects begin to degrade.
Credit: Abriah Wofford
Health and Safety
About half of the competitors earned better scores for health and safety. We monitor content temperature over time to determine how hot the contents get and whether or not they pose a potential risk for burns, scalding, or nutritional degradation. When temperatures reach over 104F, the nutritional content of the milk can begin to degrade. So, our tests record how quickly the bottle contents reach or surpass this when used under conditions similar to those used by the average caregiver and the instructions. At the highest setting, around 8.5 minutes, the contents in the bottle with Kozii managed to reach body temperature. The highest observed temperature, using the manufacturer's instructions, was 105.29. If you leave the bottle in longer than advised, that temperature can reach up to 122 degrees F at 15 minutes. This is something you clearly want to avoid for multiple reasons.
The Kozii has a single dial for warming.
Credit: Abriah Wofford
Warming Efficiency and Consistency
The Kozii performed better than average for the group and close to the top for consistency. These tests were run using the instruction manual guidelines and monitoring the bottle contents' temperatures over time to compare temperatures at different times. At 12 minutes run time, the temperature range of the contents for the Kozii was 86-93F degrees. Seven degrees of difference is much less than some competitors with more than 15 degrees of separation.
Monitoring the temperature of the bottle contents in the Kozii showed that it never reached body temperature using the manufacturer guidelines prior to auto-shutoff.
Credit: Abriah Wofford
Quickness of Warming
The Kozzi struggles to heat quickly using the manufacturer's recommendations. It earned one of the lowest scores in this metric. At auto-shutoff time, the average content temperature was only 70 degrees F, not coming close to the desired 98F. Even when we let it run for 12 minutes, it only reached 89F on average. While most babies will accept this temperature, if your little one is breastfed typically, they may be looking for closer to 98. The highest temperature we reached using the recommended settings was 93F. While you can feel pretty comfortable that you won't be overheating contents, it will be hard to wait more than 12 minutes to get the best temperature.
The Kozii has limited steps for warming.
Credit: Abriah Wofford
Ease of Use
The Kozii is super easy to use and one of the easiest in the group. The directions are straightforward, with warnings and a lot of subtext. It is not complex, and there is one dial to worry about. The main warming chart is on its own pamphlet, and while it is easy to keep on the counter, if you lose it, your manual will be no help to you.
Almost nothing could be easier to use than the single dial on the Kozii.
Credit: Abriah Wofford
You always use the same amount of water, and you can do several warming periods on the same water, which could be good for those who warm every bottle or have multiple babies. This option is easy to use with one hand if you're holding your baby in the other, and it has auto-shutoff.
Cleaning the Kozii is more complicated than most, with special brushes required to fit in crevices and a regular use of a bleach solution to keep it clean.
Credit: Abriah Wofford
Ease of Cleaning
The Kozii is middle of the road for ease of cleaning. It is not a standout, but it isn't terribly challenging. The cleaning directions are really involved and include more steps than most of the warmers. However, we suspect it might also be cleaner as it includes a bleach and water solution soak every 2-3 days, while others are largely wiping clean and occasionally descaling. If using bleach gives you pause, then it likely isn't the best option for you. Cleaning also includes descaling every two months with vinegar and water for 10-20 minutes. We like that the duration of descaling is short and is unlikely to interrupt your regular warming schedule.
The Kozzi has some nice attributes, but overall, the slow speed heating times make it generally disappointing.
Credit: Abriah Wofford
Should You Buy the Kiinde Kozii?
Unless you have the entire Kiinde system, we think there are better warmers in our lineup, according to test results. It is easy to use and clean with a consistent warming temperature, but it is super slow, and we suspect many parents will grow frustrated with how long the process is. Pair our results with the higher price, and we think that most warmer goals can be met with higher-performing or less expensive options.
What Other Bottle Warmer Should You Consider?
Our consistent, easy-to-use, and protected nutrition favorite is the First Years Gentle Warmth Digital. This warmer is reasonably priced, fairly consistent in its heating, and quicker than the Kozii. The Chicco Digital Bottle Warmer & Sterilizer also performed well in our health and safety tests and is one of the easiest in the group to use. Which option is right for you will depend on your goals and budget.
Manufacturer Video
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Juliet Spurrier, MD and Wendy Schmitz
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