NordicTrack s45i vs s25i: Which Is Right For Me?

NordicTrack s45i vs s25i

If you’ve been looking for a good treadmill for a while, you must have come across NordicTrack, a brand that stands out for its wide variety of exercise machines. Treadmills have always been NordicTrack’s specialty, with all kinds of models available at various price points for home and commercial use. The NordicTrack S-series was introduced as a budget-friendly range of compact, foldable home treadmills. In this blog post we look at the NordicTrack S45i vs S25i, with the latter being its younger sibling.  

While the NordicTrack S 25i can help you stay close to or even under the £1000 mark, spending a few hundred pounds more will get you the NordicTrack S 45i, also under £1500, and the most upgraded treadmill among its siblings. But is the additional expense worth it? Let’s get into the details to help you decide.

NordicTrack S45i vs S25i – A General Comparison of Specs

The comparison chart of the NordicTrack S45i vs. S25i below will help you get an idea about the features of both treadmills, their similarities, and their differences. Read on as we elaborate on each aspect of the two. 

Specifications NordicTrack S 45i NordicTrack S 25i

Motor 3.0 CHP 2.75 CHP
Speed 22 km/h 22 km/h
Incline 0 – 12% 0 – 12%
Running surface 51 x 140 cm 51 x 140 cm
Display 10″ HD touchscreen 7″ LCD screen
Training programs iFit Bluetooth
50+ video workouts
iFit Bluetooth
Web Connectivity Limited
Heart rate monitor
Dimensions 200 L x 90 W x 152 H cm 200 L x 90 W x 152 H cm
Product weight 88 kg 100 kg (boxed)
Max user weight 135 kg 135 kg
Warranty Motor: 10 years
Parts & Labour: 2 years
Frame: lifetime
Motor: 10 years
Parts & Labour: 2 years
Frame: lifetime

Treadmill Performance

Let’s get to the most important features first to check how well either model will work for you. The motor power, speed, and incline specifications are important when considering which treadmill to buy. These will determine the intensity of workouts a treadmill might allow without burning out.

Motor Power

Performance-wise, the S 45i is the clear winner among the two treadmills with its 3.0 CHP motor, in contrast with the 2.75 CHP of the S 25i. While you won’t be able to feel the difference if you’re only going to walk or jog, speeding up can put a strain on the S 25i’s motor in the long term. We have emphasized the importance of motor power in all our best treadmill buying guides, and for good reason. Our experts recommend at least 2.0 CHP for walking, 2.5 CHP for jogging, and 3.0 CHP for running. These are the bare minimum values you can get away with for home use, and pushing too hard on a treadmill with a weak motor can be a recipe for disaster – the machine will break down before you know it! 

Both treadmills feature a SMART-Response drive system, which means that the motor has some form of self-cooling technology and is designed to be quiet during use. We still recommend you exercise caution since, in case of any problems, the brand’s customer service is far from ideal. 

While the S 45i does fulfill the minimum requirements for running, we don’t recommend speeding up too often for long durations; it’s a home treadmill for casual users, not professional athletes. As for the S 25i, it’s best for light to moderate exercise such as walking and jogging with the occasional sprint.


The speed limits on both the NordicTrack S 45i and S 25i are identical, peaking at 22 km/h, so that’s good to have. However, we recommend speeding up sparingly on both these treadmills due to their average motor strength. The S 45i still might be able to keep up with intense running, but it has its limitations. And you know now that going very fast too often on a 2.75 CHP treadmill means setting yourself up for bad news! This is especially true if you’re on the heavier end of the weight spectrum.


Research shows that going from zero to a 7% incline increases energy expenditure by 53%, doubling your calorie burn compared to flat walking. Both these treadmills offer a maximum incline of 12%, so you can have a productive workout with either of the two. 12% incline is pretty good for a home treadmill, unless you’re specifically looking for steep uphill walking, in which case, you should consider getting an incline trainer.


User Comfort and Convenience

Too-small running decks can ruin your workout experience, as can a hard deck that causes knee and back pain. That is why it’s essential to check if the tread belt dimensions allow enough leg and elbow room and whether the treadmill has a built-in cushioning system to save your joints from harmful impact forces. 

Never undermine the importance of a treadmill’s folding feature; it’s super-convenient, especially if you live in limited-space flats. Accessory features such as workout fans and bottle holders can be very helpful too. Below we have discussed how both the treadmill models compare with regard to comfort and convenience.

Running Deck

You don’t have to worry about leg or elbow room with these treadmills, both offering identical tread belts of 51 x 140 cm. That’s enough space for a comfortable run without falling off, even for most tall runners. We’ve always been huge fans of the cushioning feature that NordicTrack integrates into its equipment. These treadmills have that in the form of FlexSelect™ technology that absorbs the impact from your strides and protects you from back and knee pain.


The S-series treadmills are known for their compact footprints. In addition, the hydraulic EasyLift™ Assist technology helps you fold up the running deck vertically against the console to free up your floor space when you’re done using it. All it takes is a gentle push for the deck to go up, so you don’t have to worry about heavy lifting.


Accessory Features

Features like console fans and accessory holders/bottle holders, etc., may seem unimportant, but they’ll definitely add up to your workout experience. Both the treadmills have AutoBreeze fans to keep you cool as you exercise. Both also have accessory holders so you can keep your essentials at hand.

Entertainment and Workout Options

We confess – running on a treadmill eventually gets boring, even for the most motivated of us! Therefore, any features that help us stay immersed in our workout are a welcome addition. A treadmill’s console display, audio features, fitness app compatibility, and built-in workout options can help you stay hooked. Here’s everything we found out about the entertainment and workout options on the S 25i and S 45i:

Display and Audio

The NordicTrack S 25i is not the best in terms of display, with a simple 7-inch LCD, but it’s not too shabby either. While the S 45i is certainly more advanced with a 10-inch iFit-compatible HD touchscreen, the S 25i does have a tablet holder and iFit Bluetooth compatibility to compensate. This means, if you have your own device, you probably won’t miss having that separate touchscreen over the console. 

The S 45i console screen needs internet connectivity to use iFit, but it doesn’t offer any web browsing options that we know about. The LCD on the S 25i doesn’t need WiFi and is only there to display your stats as you work out. Both also have two iPod-compatible 2-inch speakers to take care of your audio needs.

Workout Options

While both treadmills are iFit-compatible and come with free 1-year access to the app, there’s one major difference. The S 25i has iFit Bluetooth, which means you can use the app on your personal device and sync it with your treadmill. The S 45i, on the other hand, offers iFit in all its glory, right there on its console touchscreen. 

Let’s talk about iFit Coach. It’s a pretty cool fitness app, especially if you’re someone who gets bored easily while walking/running. The thousands of workout videos, marathons, challenges, virtual running locations, and live personal training by professional fitness coaches will make sure you stay hooked to your workout. We love how the virtual running feature has exotic locations and is designed to make your treadmill mimic the real-life terrain of your chosen path – very realistic! While it does require your credit card info even to access the free subscription, it’s a worthwhile app to have. 

As for heart rate tracking, both the treadmills have pulse sensors in the handlebars, but with the S 45i, you get the option of adding a chest belt for Bluetooth monitoring.


Other Features

Durability and Sturdiness

Some treadmills tend to look cheap, and you just know they’re not made for long-term use. Others may have small rollers that are more prone to wear, a low eight capacity, or not enough warranty. Here’s everything you should know about the durability of these two treadmills:

Overall Look and Feel

Both the S 25i and S 45i have sturdy frames and were stable enough when we tested them out. They look sleek and impressive and don’t lose points in overall feel, providing enough leg and elbow room. There also weren’t any vibrations or weird noises to be concerned about when our team tested each.

User Weight Capacity

Like most NordicTrack treadmills, both these models have a 135 kg user weight capacity. This is the average weight capacity allowed by modern treadmills of top brands. If you’re heavier or closer to the weight limit, you should consider a more heavy-duty machine, like the Sole F80 with its 150 kg weight limit.

Warranty Package

Admittedly, NordicTrack needs to work on the quality of customer service it provides. Still, it’s good to have an extensive warranty package with the purchase of both these models. There’s a lifetime warranty on the frame, a 10-year motor warranty, and 2 years on parts and labour. All this indicates the durability of these treadmills – manufacturers often don’t offer extensive warranties unless they are confident about their product quality.

Roller Size

The S 45i, as well as the S 25i have 1.9″ rollers, which should be good enough for home use. While our experts generally recommend at least 2.25-inch rollers for heavy running, 1.9 inches should be fine as long as you don’t push too hard.



According to our observation, both treadmills offer equally good value for money. While the S 45i costs a few hundred pounds more, its upgraded motor and console screen are worth the added expense, especially if you plan on speeding up often. For walkers, the S 25i can be a great choice and save them some precious pounds!


Summary and Insights

Reasons to Choose the S 25i over the S 45i

To sum up, you should choose the S 25i over the S 45i if:

  1. You’re not planning on running at high speeds and only need a treadmill for walking/jogging
  2. Your approximate budget is around £1000 (the S 25i is often available at discount)
  3. You have your own device to use iFit Bluetooth or stay entertained, and can do without an HD console touchscreen

Reasons to Choose the S 45i over the S 25i

On the contrary, the S 45i would serve you better if:

  1. You plan on speeding up often for longer periods
  2. You can afford a treadmill priced around £1500
  3. You would like an iFit-integrated touchscreen over the console

Reasons to Look for Alternative Treadmill Options

The NordicTrack S 25i and S 45i might not be the best choices if:

  1. You’re a professional heavyweight athlete. None of the S-series treadmills are designed for professional use
  2. You can afford well over £1500 for a high-quality piece of equipment
  3. You would like high-tech features such as a fancier, larger, web-enabled console screen, and a commercial-grade motor

Alternatives to the NordicTrack S-series Treadmills

Cheaper Alternative

The Sole F63 is great if you need to save a few hundred more and still get a quality machine. With a 3.0 CHP motor and a 150 kg weight capacity, this piece of equipment is built to last! While it lacks a full-color screen and fitness apps, it does offer a tablet holder on the console for your entertainment needs.

A Slightly Expensive Alternative

Spend a few hundred more and grab the NordicTrack Commercial 1750 on discount, also a folding treadmill. With the C1750, you get the S 45i’s 10” touchscreen, but much better motor power at 3.75 CHP, more durable 2.5” rollers that prevent wearing of the belt, 15% max incline, and also a 3% decline option.



The S 45i is the clear winner for us, thanks to its slightly higher motor power and better console screen. However, the S 25i is definitely something to buy if you have budget constraints and only need a walking/jogging treadmill.