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JLL S400 Folding Treadmill Review (New Generation)

Updated Jan-2021: This review has been updated to reflect the JLL S400 New Generation Treadmill which was released in 2020 (previously, we reviewed the 2019 model which was discontinued). 

Also, please be aware there are currently stock/inventory issues for this product. If you want the help deciding on a treadmill then you can contact us or check out our Compare Treadmills page.

The JLL S400 Premium Treadmill is the latest in treadmills from renowned treadmill brand JLL Fitness. This model has many different features that make this a good option for any home gym setup.

The JLL S400 is close to being on par with many treadmills you would find at your local fitness centre. Unlike many home models, JLL provides superior functionality and a solid 5-year warranty on the motor and lifetime warranty on the frame.

The S400 is the premium sister to the very popular JLL S300 treadmill. The main difference between the two is the larger running deck and the inclusion of Bluetooth connectivity for the built-in speakers on the S400. Other than these two features they are virtually identical.

JLL S400 Folding Treadmill, 2022 New Generation Digital Control 4.5HP Motor, Large Running Area, 20 Level Incline, 15 Programmes, Speakers, Bluetooth, USB & AUX, 16 Point Cushion Deck, LCD Display

  • 16-point cushion deck shock absorption system
  • Electric auto-incline with 20 levels up to a 12% angle
  • Large 5.5" LCD screen with blue backlight
  • 15 running programs including 3 customisable options
  • Good quality built-in speakers 
  • Bluetooth and USB connection for iPod/iPhone/MP3 player connectivity

Functions and Performance

Do you really want to figure out your own program? No one does. People usually want to jump on their treadmill and go for a run without putting a lot of thought into varying speeds and inclines along the way.

There are 15 built-in programs for you to start with ranging from easy to difficult.

However, if you do want to take complete control over your program, you can. The other three options are programmable by you. This is great if you are the sort of person who wants to create their own interval running programs to use on a regular basis.

There are even high-powered speakers, so you can connect your iPhone or other device to the treadmill and listen to your favourite songs while you run either via Aux input or Bluetooth.

JLL S400 LCD Screen

My one criticism is the heart rate monitor in the handrails. These are difficult to use when running at a more than a moderate pace and not always accurate.

I would have liked to see the ability to connect a heart rate strap to the display via the otherwise excellent Bluetooth capability.

The treadmill also now comes equipped with a pause function for emergencies or for just taking a break. You can pause your workout by pressing the STOP button once and then when you are ready you can continue from where you left off.

Noise Level

Once you step foot on the treadmill, you’ll notice that this treadmill is a little different than cheaper options. Why? There is a built-in shock absorption system.

The JLL S400 Premium Treadmill has a 16-point cushion system that reduces both the sound from your shoes hitting the running deck but also the impact on your joints.


As far as the motor goes, you get a continuous 2.5 HP motor with 1800 W that can bump itself up to a peak of 4.5 HP and 3350 watts. That way, you’re going to have all the power you need to keep the track spinning at precisely the speed and incline you want.

The motor delivers a wide range of speeds going from 0.3 km/h to a steaming-along 16 km/h. So you’re not going to have a problem getting a speed you can feel comfortable with, no matter your capabilities.

Incline Levels

Want to test your endurance even more? You’re able to change between 20 different incline levels (up to 12 degrees).

You can easily adjust the elevation with the incline buttons located on the handrail. The handrails also have the speed buttons and heart rate sensors built-in.

Power incline is a benefit of many mid-range and premium treadmills, in that you can vary the steepness without having to stop, get off the treadmill and make the adjustment manually.

You can achieve a higher intensity workout and accelerated weight loss with the 20-level incline which is equal to a 12% incline. 

Size and Weight

The JLL S400 is solidly built from good quality steel. As with most folding treadmills, there is sometimes frame vibration at higher speeds, especially with larger runners.

This is a reasonable trade-off in my opinion given the storage benefits, and not a big deal given the quality construction of this treadmill.

JLL S400 Size and Weight

The JLL S400 dimensions are:

  • Assembled Dimensions: 170 L x 70 W x 134 H cm
  • Folded Dimensions: 110 L x 70 W x 134 H cm
  • Running Area: 135 L x 45 W cm
  • Product Weight: 69 kg
JLL S400 Dimensions

The video below from the JLL Fitness Warehouse will give you a good idea of the size and construction of the JLL S400 treadmill.

Assembly and Delivery

The S400 will be Delivered to a 'ground floor' location of your choice. The treadmill comes in two boxes, one for the motor and the other with the frame. 

It is very heavy (a good thing) and does require more than one person to move around. If you want it upstairs sometimes if you speak nicely to the delivery folks they will help you out.

Assembly is relatively straight forward although the instructions are not the best I've seen. This is unfortunately common with treadmill manufacturers taking some weird pleasure in seeing who can write the most confusing instructions!

Having two people certainly helps with assembly (and if you need to move the boxes yourself). However, once assembled it is easy to fold and store away with one person.

Max User Weight

The maximum user weight for this model is 120 kg (approx 19 stone or 260 lb). It also has adjustable weight settings in the LCD computer to calculate the number of calories you're burning correctly.

Compared to the JLL S300 Model

The differences between the JLL S400 and the JLL S300 treadmill is mostly in the size of the running area and the inclusion of Bluetooth connectivity for the speakers. The JLL S400 treadmill boasts a running deck with an additional 12cm in length and 4cm in width compared to the S300.

So if you are average height or below and aren't interested in the Bluetooth feature then give the JLL S300 a look as it's about 25% cheaper.


JLL S400 Folding Treadmill, 2022 New Generation Digital Control 4.5HP Motor, Large Running Area, 20 Level Incline, 15 Programmes, Speakers, Bluetooth, USB & AUX, 16 Point Cushion Deck, LCD Display


  • Huge running deck (135 x 45cm)
  • Slowest start speed at 0.3km/h (makes it extremely safe for vulnerable or elderly)
  • 16km/h top speed
  • 15 running programs including customisable ones
  • Comes with decent warranty, 5 year motor guarantee and lifetime guarantee on frame


  • Some reports of long delivery wait times. If you are in a hurry, this may not be for you. (As of January 2021)
  • When folded it still occupies a larger amount of space than you think.

The JLL S400 Treadmill has many premium features if fact you'll find very little not to like with this model. It’s high quality with a mid-range price, it’s durable, and the warranty is exceptional.

The digital LCD tracks all your vital statistics, such as calories burned, distance and heart rate. You can also connect via bluetooth to your smartphone or tablet to listen to music through the high-powered onboard speakers.

The JLL S400 provides near a commercial-grade quality at a price most home users can live with - so whether you’re trying to build stamina, lose weight or gain muscle, this is an ideal treadmill to consider.

Related Posts:

JLL D100 Treadmill

Last update on 2022-07-24 / Amazon Product Advertising API

About the author

I'm Jamie and I test out new models in sports retailers, or buy and sell them new or second hand so I can review a wide range of models and put together the best advise on which treadmill is right for you. So if you are looking for a cheap treadmill for walking, a gym quality treadmill to run sprints, or something in-between I can point you in the right direction.