Does Hotronics S4 Really Work? Our Honest Review


There are a ton of different foot heating options on the market today. You can go with disposable insoles, merino wool socks, or even electric socks. However, a new option has recently hit the market – the Hotronics FootWarmer S4 Universal Boot Heater.

Are these a solid option for your cold winter activities? Do they really work well, or are there better options out there? The short answer is yes, these are some of the best boot heaters on the market today.

Below, we will outline everything you need to know about these high-quality, powerful foot warmers.

Click here if you would like to skip the review and go directly to the product page on

Product Name
Buy Online
Hotronic FootWarmer S4 Universal Boot Heater
Powerful, high quality foot warmer with included insoles, perfect for all winter activities

Shop Now At

Hotronic FootWarmer S4 Fits In All Types Of Footwear, Easily Transferable

The Hotronic FootWarmer S4 Universal Boot Heater comes with two pairs of Hotronic’s One Size Fits All – Heat Ready Insoles.

These can be easily moved into any different type of footwear, whether it is your ski boots, snow-shoes, fishing boots, or even just your sneakers. This is one of the best features of the Hotronics S4 – they can be placed anywhere with ease.

In fact, with a little bit of tinkering, the warming elements can be placed into any type of insoles or orthotics.

This makes the FootWarmer easily transferable and reusable for all of your cold weather activities. If you just want to place the FootWarmers into a pair of boots without placing them in orthodics, that can easily be done as well.

Simply utilize the provided clips to attach the heating packs and start receiving the heat you need.

Keeps Your Feet Warm All Day With 4 Heat Settings

The Hotronic FootWarmer S4 Universal has three powerful heat settings to keep your feet warm all day, whether you are out cycling, hitting the slopes, or ice fishing.

Additionally, they have included a blast heating settings to neutralize the most extreme colds and keep your blood circulating.

The Hotronics Battery back utilizes high capacity NiMH AA cells that can be topped off without needing to fully recharge the batteries.

These are some impressive times that last significantly longer than other foot heating products that are currently on the market.

16.5 - 21 Hours
7-10.5 Hours
5-7.5 Hours
2.5-4.5 Hours

Perfect For All Winter Activities, Even Extreme Temperatures

hotronics s4 review

The Hotronics S4 works in all types of weather, even the most extremely brutal cold fronts.

In fact, the S4 functions in -30 Celsius temperates, making this the perfect addition for all of your winter activities, whether you are skiing, bicycling, horse-back riding, or just have cold feet and poor circulation.

The provided insoles provide effect coverage of the toes and feet, neutralizing the cold and letting you get back to the activities that you love.

What Is Included In The Package?

The Hotronics FootWarmer S4 Universal includes:

  • 2 S4 Battery Packs
  • 2 Heating Elements
  • 2 Cambrelle Covers
  • 2 Heating Hotronics Insoles
  • Hotronics ReCharger Power Plus

Essentially, the package contains everything you need, whether you want to use the provided insoles, or install them into your own custom orthotics or footwear.

It is important to note that the included charger, known as the ReCharger Plus works on a global input range of 100v to 240v. This means that the charger should work in various countries around the world.

What Is The Difference Between Hotronics S4 Universal and Hotronics S4 Custom?

The only difference between the Hotronics FootWarmer S4 Universal and the Hotronics FootWarmer S4 Custom is that the Custom set does not include the pair of one size fits all insoles.

If you already have a pair of custom insoles or orthotics and you do not want a backup, this is the solution for you.

However, it is always a great idea to have a backup pair of insoles, which is why we recommend the Universal kit.

What Is The Difference Between Hotronic S3 vs S4?

The main difference between the Hotronic S3 and the S4 is the increased duration of the S4 battery pack. On average, the S4 lasts anywhere from 30 minutes to 3 hours longer depending on which heat setting is used.

This is a substantial change and is a worthy addition to the Hotronic FootWarmer line of products.

Will The Hotronics Insoles Fit In Any Pair Of Footwear?

hotronics s4

Yes! With a little bit of installation, the Hotronics S4 FootWarmer Universal will work in any pair of custom orthotics or footwear.

Additionally, there is a pair of insoles that are included in the set, so you can use those as well if need be.

Are The Hotronics S4 Insoles One-Size-Fits-All?

Yes, the Hotronics insoles are one size fits all. This means that they will work for you if you are a man, woman, or child.

Where Should I Purchase the Hotronic FootWarmer S4 Universal Boot Heater?

We recommend purchasing the Hotronic FootWarmer S4 Universal Boot Heater on Amazon. Click here to go directly to the product page on

Hotronics S4 Positives and Negatives


  • Powerful, long-lasting battery
  • Three different heating types plus a blast heat setting
  • One-size-fits-all insoles
  • High build quality, can be placed into any type of shoe or boot


  • One of the more expensive foot warming options

Our Verdict

The Hotronic FootWarmer S4 Universal Boot Heater is by far one of the best boot heating options on the market today.

The build quality is high, the S4 batteries can get surprisingly warm while lasting hours upon hours and the makers were nice enough to include a one-size-fits-all set of insoles.

While it is one of the more expensive options for boot heaters, it is totally worth it for the high-quality build and the all-day heat that these provide.

Feel free to leave any comments or questions regarding the Hotronic S4 FootWarmer below.

Click the button below to purchase Hotronics FootWarmer S4 Universal Boot Heater on

Shop Now At