The 2 Best Bottle Warmers of 2025

Top pick

This warmer is the most efficient and reliable of those we tested, and it’s one of the few that doesn’t need fresh water every cycle. But it can still overheat milk and the cleaning process is involved.

Of all the bottle warmers we tested, the Kiinde Koziii did the best job of warming baby formula to around 98 °F (our expert-recommended temperature) without overheating. The device turns on with the twist of a dial that works (and ticks) like a kitchen timer, which means you ultimately control how long you expose your baby’s milk or formula to heat. It’s not inexpensive, and the cleaning process is involved. Still, the Kozii’s reliable heating and simple interface set it apart from every other bottle warmer we’ve tested over the years.

It’s more efficient and reliable than other warmers. The Kozii does a better job of quickly warming bottles to the ideal, 98-degree temperature than any other model we’ve tested. It heated a plastic 4-ounce Philips Avent bottle to 98 °F in just 6 minutes, and a plastic 8-ounce Lansinoh bottle in 8 minutes 30 seconds. We consider this to be successful, given that you can heat breast milk or formula to a similar temperature in 7 minutes 30 seconds in a bowl of hot water from a kettle — and preparing water in a kettle takes additional time.

When we originally tested the Kozii in 2017, we found it was faster than competitor models, except for steam warmers like an earlier version of The First Years Simple Serve Fast. There are now some models (like the Philips Avent Premium Fast Baby Bottle Warmer) that use a water bath to heat formula more rapidly than the Kozii, but they aren’t as accurate or consistent.

A water reservoir reduces the chance of overheating. The Kozii is the only model we tested that uses a circulating water bath, as opposed to the still water bath seen in other water-bath warmers. The water recedes into a reservoir at the base of the device as soon as the heating cycle is complete and then the device turns off, which means you’re less likely to overheat bottles using the Kozii than with other models. In only one instance during our 2024 testing, the Kozii came close to overheating a glass, 4-ounce Evenflo bottle with a final temperature of 101 °F.

It has the most effective auto-shutoff of any model we tested. Part of the appeal of a bottle warmer is that you can tend to another task — like changing a diaper or making coffee — while the device does its work. But warmers without an auto-shutoff require constant supervision, since leaving the bottle on the warmer for even one additional minute can cause the contents to become dangerously hot. The Kozii’s auto-shutoff is unlike any other on the market. The entire machine shuts off after the heating cycle and, unlike with other water-bath warmers, the water recedes, so the heat source is removed. (Though you can still overheat bottles if you miscalculate the heating time or leave the bottle in the device for a long time even after it’s turned off.)

Competitor models with a more traditional auto-shutoff, like The First Years Simple Serve (our budget pick) and Kiinde Kozii SafeHeat Pro, expose bottles to residual heat even once they’ve turned off. Several other models we tested only shut off after 45 minutes or one hour, which is too long to expose milk or formula to heat because bacteria can develop.

You don’t have to fill the Kozii with water every time. This is one of the easiest warmers to use because it doesn’t require measuring a precise amount of water. You add water to the basin so it rises above the pump valve and turn the dial to the appropriate setting for the bottle you want to warm — this is a more simple process than setting a digital timer on competing models. Another perk: You don’t need to empty the device of water after each use.

You can fine-tune the heating cycle. The manual includes a reference chart of approximate warming times when setting the dial. Once you get a feel for how long it takes to heat your baby’s bottles, the user-interface is easy to program. You can set the dial to the anticipated warming time and make minor adjustments in 30-second increments.

It’s also easy to add another minute or two after the cycle is complete if, after sampling the temperature of the milk or formula on your skin, you find the need to heat the bottle a little longer. And the fact that the dial counts down like a kitchen timer means you always know how long you have to wait before your baby’s bottle is ready.

It’s compatible with most bottle types. You can use the Kozii with narrow-neck, wide-neck, silicone, plastic, and glass bottles from many leading brands.

It can heat bottles back-to-back. Many bottle warmers require you to add cool water and/or wait up to 10 minutes between heating cycles. With the Kozii, caregivers can prepare one bottle after another; per the instructions, you simply reduce subsequent heating cycles by 30 seconds.

Flaws but not dealbreakers

The signals could be more clear. Some warmers have blinking lights and beeps to indicate the heating cycle is complete. The Kozii makes a subtle ticking sound throughout the heating cycle; the end of the ticking means your bottle is ready. We would prefer a more obvious indicator.

We don’t recommend using the Kozii to heat frozen breast milk. The Kozii easily accommodates frozen breast milk pouches, but we found it heats them unevenly. During testing, some portions of our milk reached more than 120° F, whereas other areas remained frozen.

The cleaning process is involved. The instruction manual says to clean the Kozii every two to three days by emptying the water chamber and refilling it with a cup of fresh water mixed with mild soap. Every two months, it calls for descaling the Kozii by mixing a half cup of white vinegar with 1 cup of water and pouring the mixture into the machine. You let it sit for 10 to 20 minutes, empty it, and rinse it. And one Wirecutter staffer who has owned the Kozii for two years noted that there isn’t a way to dissemble the machine to really scrub or wash it.