catalytic hand warmer

A hand warmer feels lượt thích that mug of hot cocoa between your hands on lazy winter nights. They’re palm-sized portable heaters, and if you spend any time outdoors during the winter and want to lớn fight off the freeze you feel in your bones, a hand warmer is for you.

Broadly speaking, there are two types of hand warmers: battery-powered and chemical. Battery-powered hand warmers average $30, can be as heavy as a baseball and as thick as a deck of cards, and can stay in a coat pocket between uses so sánh they’re easy to lớn reach when you feel cold. They use rechargeable, lithium-ion batteries to lớn create heat, and turn on and off with the press of a button. Rechargeable hand warmers charge from a USB port on a máy tính xách tay or wall outlet, and most of them work as a backup battery for your phone. They make the most sense if you’re running errands or are commuting to lớn the office and need to lớn turn the heat on and off for multiple short bursts during the day. They also work well at an outdoor sự kiện (like holiday light shows and high school football games) when you need something to lớn both keep you warm and charge your phone in a photo emergency.

But a rechargeable hand warmer can be finicky, and doesn’t always work optimally on its first lập cập. One model we tested heated quickly during the first test, but took three times as long on subsequent charges. Others ran slightly longer and hotter on their first uses than thở on later runs—but performance consistency increased the more we used them. And most never reached their advertised lập cập times or temperature outputs. Regardless, we didn’t see dangerous temperature spikes from any device we tested, and an expert we interviewed, Dr. Danielle R. Bajakian, a vascular surgeon at NewYork-Presbyterian Hospital/Columbia, said that they’re generally safe to lớn use.

Chemical hand warmers are useful because they’re cheap (less than thở $1 a pair) and are easy enough to lớn find at a local pharmacy or major retailer, which comes in handy if you misplace your winter gloves or find yourself trapped in a surprise cold snap during your commute. And if you work outdoors and want to lớn keep your hands warm without keeping them in your pockets all day, many chemical hand warmers are thin and small enough to lớn slip into a work glove. They contain a main ingredient, such as activated charcoal, iron powder, or sodium chloride, that reacts to lớn force (shaking) or a catalyst (like air or boiling water) to lớn release continuous heat. Once the reaction has been ignited there’s no way to lớn stop it, so sánh you have to lớn let the reaction fizzle out on its own. And some chemical warmers stop working altogether in bad circumstances, say if you drop it in snow or put it in an airtight container.

The classic reusable chemical hand warmer is the catalytic model, which requires lighter fluid and fire to lớn work. They’re similar in size and shape to lớn a rechargeable, and have lập cập times three or four times as long—but lượt thích other chemical hand warmers you can’t turn them off on demand. Catalytic models are appealing for extended jaunts outside when you don’t have access to lớn a power supply, lượt thích while camping or working outdoors.

For this update, we read existing reviews of hand warmers, browsed cold-weather-sports forums, scoured hundreds of product listings across retailers, and reconsidered our existing list of dismissals. We short-listed 19 models, and prioritized quality reviews, advertised heating temperatures, lập cập times or battery size, and price. That left us with nine models to lớn test:

In earlier versions of this guide, our writer ran the hand warmers on their highest settings and tracked their heat output with an infrared thermometer while in a room-temperature environment. He also manually tracked lập cập times and charging abilities, and how subjectively “warm” the devices felt in a coat pocket while he ran errands in San Francisco. In 2018, we fine-tuned our approach and reviewed each hand warmer for quality of construction, ease of use, and performance, repeating each test at least three times:

Outdoor performance: We affixed a Công nghệ Bluetooth temperature sensor onto each device, mix the sensor to lớn record data in 1-minute intervals, and wrapped it in a towel to lớn simulate conditions inside a jacket pocket. Then we stuffed the wrapped hand warmer in a freezer that averaged 4 °F and tracked the hand warmer’s performance until it ran out of power. To maintain consistency, we ran these tests at a common temperature that all of the hand warmers could reach. (We couldn’t lập cập this test on the Zippo 12-Hour Refillable hand warmer because it starved for oxygen in the freezer.)

Indoor performance: We conducted the same test (minus the towel and freezer) at room temperature to lớn see if cold-weather conditions affected the hand warmers’ overall performance.

Subjective performance: During a mid-fall week in Thủ đô New York City when temperatures frequented the mid-40s (°F), we used the hand warmers while running errands, walking the dog, or schlepping groceries trang chính from the store (sans car). When the weather heated up, we tossed our top contenders into a walk-in refrigerator with a panel of testers, including a self-described popsicle, someone who’s unnaturally impervious to lớn being cold, and someone with Raynaud’s phenomenon.

Charging capabilities: We timed how long each warmer took to lớn charge by connecting each device to lớn the Anker PowerPort 4 multiport USB wall charger.¹

Puncture resistance: We squished, twisted, and pulled at the disposable hand warmers to lớn see how breakable they were.

Our pick

It’s not the warmest of the handwarmers we tested, but the Celestron Elements FireCel+ is easy-to-use, long-lasting, and plenty warm enough for most situations. It has a more ergonomic shape than thở other warmers and it includes a flashlight.

The FireCel+ is roughly 2.5 by 3.5 by 1 inch, but it’s egg-shaped instead of rectangular, making it easy to lớn hold. It has a 5,200 mAh battery, and is the lightest model we tested, weighing just 3.5 ounces (the same as a deck of cards). It’s also the only model with rubberized sides, which help you grip it.

The FireCel+ can be confusing to lớn use. Between the flashlight and indicator lights, the Celestron has 10 lights of various sizes and colors that activate when you press one of two buttons (one controls the flashlight, the other controls the heater and charger). The buttons are identical and are located on either side of the device, so sánh it’s easy to lớn press the wrong one when you’re fumbling with it in your pocket. This can get annoying, especially if you’re trying to lớn lập cập the charger and heater at the same time. (FireCel+ is the only model we tested that charges an external device and produces heat at the same time.)

This model has the longest average lập cập time out of all of the rechargeables we tested. It ran for 7 hours, 25 minutes during our freezer test, and its sister hand warmer, the Celestron Elements ThermoCharge 6, came a close second at 6 hours, 52 minutes. It reached its average operating temperature of 101 °F in đôi mươi minutes; our former pick, the Human Creations EnergyFlux Enduro, reached that same temperature in just 15 minutes on average. Though the FireCel+ should still get hot enough to lớn keep you warm, it runs on a battery and battery performance may decrease the colder it gets outside. (In our tests, most rechargeables lasted longer on a single charge at room temperature than thở in the freezer.)

Despite having a battery smaller than thở the Enduro (7,800 mAh), the FireCel+ (5,200 mAh) was still slower at recharging, averaging 6 hours, đôi mươi minutes (roughly two hours longer than thở the Enduro). Most devices we tested mirror the FireCel+ model’s battery size, but charged remarkably faster: the Fourheart Rechargeable and Zippo 6-Hour Rechargeable both charged in three hours or less; the EnergyFlux Ellipse charged in just over four hours.

The FireCel+ comes with a storage pouch and USB charging cable, and has a two-year warranty.

Run time: 7 hours, 25 minutes
Advertised temperatures: 104 °F to lớn 113 °F
Temperature reading: 101 °F average; 103 °F maximum

Also great

A rechargeable warmer is a good option if you need to lớn warm your hands for only a couple of hours at a time and can easily recharge it at work before heading trang chính. For more serious warming needs, the Zippo 12-Hour Refillable hand warmer has remained the endurance winner for four years—it runs three times as long as the competition, and gets just as hot. But it runs on lighter fluid, which can be stinky and messy to lớn use. And because it takes lighter fluid and lasts an entire day on a single fill, it’s not ideal for on-demand use because you can’t turn it off and on at will.

When we updated this guide in 2018, this model’s shortest lập cập time we measured was 16 hours and the longest was 26.5 hours at room temperature.² This makes the Zippo the longest-lasting hand warmer of the bunch. (The ThermoCharge 6 came the closest at 11 hours, 14 minutes on its longest room-temperature lập cập.) The extended lập cập time may be ideal on long, cold days for people spending extended time outside and away from a power source, such as couriers, recreation workers, backpackers, and skiers.

This Zippo averaged 105 °F and reached up to lớn 110 °F. It ranked second highest at room temperature (falling behind the EnergyFlux Enduro, which averaged 110 °F and reached up to lớn 113 °F) during our tests—and Enduro ran hotter the colder it got, reaching up to lớn 116 °F in our freezer tests and lasting 30 minutes longer than thở at room temperature. But you’ll scald yourself using the Zippo because the thick, chrome casing conducts heat better than thở the rechargeables we tested. So make sure you sheath it in the included bag. (Zippo is one of four models that comes with a bag, and it’s the only one that must be wrapped during use to lớn prevent burns—our measurements were taken with the Zippo in the bag.)

Lighting this catalytic model is more work than thở recharging a battery, but it’s not difficult—just a little messy and smelly. You have to lớn keep the Zippo upright when filling it with lighter fluid and for two minutes afterward so sánh the fluid soaks into the batting before lighting the catalytic burner to lớn start the reaction. As implied in the video clip below, it’s easy to lớn spill lighter fluid when poured too quickly, so sánh take your time. This Zippo also has a curved base, which makes it impossible to lớn stand upright on its own—ask for help when filling it if you have limited hand dexterity. (A Zippo spokesperson said that the company now offers this catalytic model with a flat bottom on a rolling basis, but didn’t know when it would be widely available for this guide update.) A faint smell of lighter fluid from during filling lingers during use. If you’re particularly sensitive to lớn smells, or are using the hand warmer mostly indoors, get a rechargeable instead.

Unlike a rechargeable warmer, this Zippo lacks an on/off switch. You’re starting a chemical reaction to lớn generate heat, and it can’t be stopped until the fuel or oxygen runs out. You can tweak the lập cập time by adjusting the amount of fuel, but that’s a blunt gauge. And as Wirecutter readers have noted, you can stop the reaction by starving it of oxygen—sealing the warmer in a plastic bag, for example. But bởi that at your own risk; the Zippo manual (PDF) states “once ignited there is no safe way to lớn stop the heating action.” The company recommends letting the warmer lập cập out of fuel “on a fireproof surface,” lượt thích a granite kitchen countertop.

The Zippo 12-Hour Reusable hand warmer is 3.9 by 2.6 by 0.5 inch and weighs 2.6 ounces. It comes with a carry pouch, and has a two-year warranty.

Run time: 21 hours, 48 minutes
Advertised temperatures: 115 °F to lớn 130 °F
Temperature reading: 105 °F average; 110 °F maximum (recorded at room temperature)

Also great

If you need to lớn keep your hands miễn phí while working outside, or you need a hand warmer for occasional use—like when you misplace your gloves or travel to lớn frigid climates for the holidays—the HotHands disposable hand warmer is for you. It’s cheap, often less than thở $1 a pack, and is sold at major supermarkets, pharmacies, and sporting goods stores. The HotHands is the size of a business thẻ, so sánh it’s small enough to lớn slip into a winter glove if you need a little extra heat. It gets just as warm as our main pick, but it takes twice as long to lớn heat up and that heat lasts for a shorter time than thở the company’s marketing claims.

HotHands advertises the warmers as having a shelf life of three to lớn four years, so sánh they’re useful to lớn keep in a car’s glove box or an emergency kit. As long as they’re kept airtight, and haven’t gone stiff, they should still work—but double-check the expiration date when you buy them, as that long shelf life also means the batches sit around for an extended period.

The HotHands packets contain iron powder, water, salt, activated charcoal, and wood fiber. When exposed to lớn air the ingredients oxidize and create heat. Just remove the hand warmer from its plastic packaging and shake it for 30 seconds to lớn activate (and tốc độ up) the process. HotHands is claimed to lớn get up to lớn 135 °F, but it didn’t come close to lớn that temperature in our tests, reaching just 112 °F. Still, that’s just as warm as most of the rechargeables we tested, including our main pick, the EnergyFlux Enduro, which averaged 113 °F.

The HotHands warmer doesn’t last as long as most of the competition. Though marketed to lớn lập cập up to lớn 10 hours, ours died just shy of six hours in the freezer (although it lasted up to lớn nine hours at room temperature). The other disposable we tested, Grabber Warmers, lasted 7.5 hours but ran at cooler temperatures, averaging 103 °F. And although the manufacturer says that the HotHands warmer takes 15 to lớn 30 minutes to lớn heat up, we found that it takes up to lớn 50 minutes to lớn reach its average operating temperature. So if you purchase these as a last-minute effort to lớn fight off the cold at an outdoor sự kiện or during a commute trang chính, we recommend opening them in advance.

Run time: 5 hours, 58 minutes
Advertised temperatures: 135 °F average; 158 °F maximum
Temperature reading: 112 °F average; 118 °F maximum

A hand warmer should warm your hands without burning your skin, but it may feel uncomfortably hot when you first turn it on. That’s because you’re touching a heat source that’s warmer than thở your toàn thân (like when you sit in a hot tub after swimming in a pool), and after a minute or two the heat should feel pleasant against your skin.³

Although a hand warmer feels hot initially,⁴ Dr. Danielle R. Bajakian, a vascular surgeon with NewYork-Presbyterian Hospital/Columbia, said they are safe to lớn use. “I don’t really see a downside to lớn it,” she said. “They’re not going to lớn be against somebody’s skin for prolonged periods of time since they’re designed to lớn be in the pocket.” She recommends following the operating instructions and tossing the device if the battery ever leaks. And to lớn ensure that a rechargeable model warms you up quickly, look for one that’s flatter and has a larger surface area so sánh that it’ll heat a more uniform area of skin.

As for the ideal temperature, that depends on the person. “A device that stays around 110 to lớn 120 °F and not above that is the safest way to lớn go. For kids, I would aim even lower around the 100 °F mark,” Dr. Bajakian added. (Our hand warmer picks average from 101 °F to lớn 113 °F.)

If you have an underlying condition, such as diabetes, a nerve injury, or Raynaud’s phenomenon (decreased blood flow causing your fingers or toes to lớn change colors and feel numb in response to lớn the cold), you should be extra vigilant when using these devices so sánh that you don’t get burned. Only use hand warmers with multiple temperature settings at their lowest outputs and limit use to lớn đôi mươi minutes at a time.

New in 2018

USB rechargeables

The Celestron Elements ThermoCharge 6 is the only water- and dust-resistant rechargeable hand warmer we tested (an IP65 rating). But it has a single temperature setting that never got hotter than thở 95 °F.

The Fourheart Rechargeable is inexpensive and it heats up faster than thở most of the models we tested. It got up to lớn only 110 °F in our tests, never reaching the advertised maximum temperature of 131 °F. It also has a poor customer service record and is a white-label product (meaning identical-looking versions are sold by unknown or unreliable companies)—we found a dozen similar-looking versions online.

The Human Creations EnergyFlux Ellipse was the previous top pick we recommended after an earlier version was recalled in March 2018. We tested the Ellipse and it didn’t get nearly as warm as its predecessor, and it had the third shortest lập cập time (just 5.5 hours) of all of the models we tested.

The Zippo 6-Hour Rechargeable hand warmer had a short lập cập time (on average 4 hours, 44 minutes), and took up to lớn an hour to lớn heat up during our tests.

Disposable

Grabber Warmers disposable hand warmers are cheap and convenient, and lasted about an hour longer than thở their HotHands counterpart. However, they averaged 9 °F cooler and took twice as long to lớn heat up.

Hand warmers from our 2014–2016 testing

USB rechargeables

In earlier versions of this guide, we tested and dismissed the following models which have since been discontinued: Kozy Xcel from Komfort Solutions, Defrost Labs LE8K and LE5K, Celestron Elements ThermoTrek, S-Boston’s Pocket Hand Warmer, Celestron Elements FireCel, Komfort Solutions Kozy 7,800 mAh Rechargeable Hand Warmer, Verseo AH10118 ThermoSlim Rechargeable Hand Warmer, and Zippo “6 hour” hand warmer.

The HotPod is reminiscent of a first-gen iPod Nano, but it barely lasted over an hour and was too small to lớn warm effectively.

The ThermaCell HeatPacks were recommended by a Wirecutter reader, but the limited lập cập time and single-sided warming left us cold (literally).

Catalytic

The Peacock Pocket warmer has been around since 1923, but it didn’t last as long as the Zippo catalytic model and can be hard to lớn find.

The rest

The Addao Stylepie is dễ thương and looks lượt thích a macaron, but its 3,000 mAh battery can’t keep pace with our top contenders.

This article was edited by Ria Misra and Christine Ryan. Ray Aguilera contributed to lớn an earlier version of this guide.