How To Tighten A Treadmill Belt (Adjust, Align & How Tight?)

Treadmills help you stay in shape and reduce the risk of injury associated with outdoor running. There’s a wide variety of treadmills for walking or running, and you can find them in every gym.

Over the past few years, we've also seen a lot more people buying treadmills to use at home too. This is great for personal fitness, but you need to understand how to maintain them properly.  

Treadmills are made up of many components, but the most crucial part is the running belt. The belt needs to be fitted correctly and with the proper tension so you can use the treadmill safely. This guide will explain how to tell when your belt is loose and how to tighten treadmill belt correctly.  

The treadmill belt, sometimes called the track, walking belt, or running belt, is the part of the device you’ll have the most contact with. It goes across the top of the treadmill deck, and it’s the component that your feet will land on as you’re running.  

The treadmill belt is designed to glide smoothly over the rollers, so you have a running surface that moves with you. It will help to absorb the impact when you land so that there’s considerably less impact on your joints than hitting the ground. This helps to protect your body while you exercise on a treadmill 

There are different types of treadmills, but generally, all belts are pretty similar. They are primarily made from rubber, but there are three different thicknesses to choose from: 

  • Single Ply  
    This is a single piece of rubber that is wrapped around your treadmill deck. It’s generally the simplest and cheapest option.  
  • 2-Ply  
    With 2-ply belts, the top is made from rubber or rubber PVC, and the underside is made from cotton, polyester, urethane, or sometimes mono-filament. This makes the belt a little heavier but much more durable. Plus, the bottom layer helps to make the belt quieter which is perfect in a home gym situation. The majority of treadmills have a 2-ply belt, and it's often considered the middle-road best option.  
  • 4-Ply   
    These are the heaviest type of belts with additional layers added in. Often this is rubber, but sometimes 4-ply counts the layer of glue as an actual layer. These types of belts are more durable but can be expensive. They help dissipate the heat generated on the belt to keep it cool, and the cushioning can make them quiet. The disadvantage is that the extra weight can put a strain on your mechanism and impact the longevity of the treadmill Your treadmill belt is an important component that lets you exercise effectively and safely, so it's good to understand what you have going on under your feet.  
What Is A Treadmill Belt

Reasons Why Your Treadmill Belt Might Be Slipping 

Before you can solve the issue with your treadmill belt, it’s good to understand why it’s happening. Here are the main reasons that your treadmill belt might be slipping: 

Drive Belt May Be Loose 

The drive belt connects the motor to the front roller. If this becomes loose, then the front roller can start to slow down and speed up randomly. This will cause the treadmill belt to slip and can be hazardous to the user. You’ll need to tighten or replace the drive belt to solve this issue.  

Walking Belt May Be Too Loose 

The most common reason for slipping is that the walking belt is too loose, which happens naturally over time because the rubber stretches out. This will cause the belt to slip, and if it becomes too loose, the treadmill might not work at all. You can check if the walking belt is too loose by seeing if you can lift it more than a few inches from the treadmill deck. If it is too loose, you'll need to tighten it before using the treadmill again. 

The Belt Needs Lubrication 

Your treadmill belt has a lubricant applied to the underside so that it can glide over the rollers. This is usually a silicone lubricant that will last a while, but it will eventually dry out. When the lubricant starts to dry out, the belt can jolt or slip when you’re using it, which makes it a safety hazard.  

You can reapply the lubricant yourself fairly easily by purchasing a new spray-on lubricant, removing the treadmill belt, and applying it to the underside. Make sure you consult the manufacturer's guide to check which lubricants work with the material first.  

The Pulley OThe Front Roller May Have Lost Its Grip 

The pulley is used to align the belt and keep the weight balanced. If the pulley has lost its grip, then the belt will start to drift off to one side and can start to slip. Eventually, if left unchecked, the whole belt can slip from the treadmill, which is a huge risk to any user. If your belt is starting to go to one side, check the front roller because it may need to be replaced.  

How To Tighten Treadmill Belt

Adjusting Treadmill Belts (How To Guide) 

To adjust the treadmill belt, you won’t really need many tools but make sure you have a good wrench handy. Note that some treadmills will require an Allen wrench. 

There are three main issues that come up, and we’ve dealt with each one separately here:

1. How To Tighten Treadmill Belt  

If your treadmill belt isn’t moving correctly, then it's probably too tight. Lift the belt from the center, and if you can't lift it 3-4 inches and fit your hand under, then it's probably too tight. If that's the case, then follow these steps: 

  1. 1
    Disconnect The Treadmill  
    Make sure the treadmill is completely disconnected and switched off before starting. This is important to make sure you stay safe.  
  2. 2
    Locate The Roller Bolts  
    Your treadmill will have two roller bolts on the base at the rear, one on the left and one on the right.  
  3. 3
    Loosen The Bolts  
    Use your wrench to loosen the bolts by turning them to the left one quarter turn at a time. Make sure you loosen both bolts in sequence, or you could damage the belt.  
  4. 4
    Check The Belt  
    After every quarter, turn on both bolts check the belt again. Keep going until you can lift the belt and fit your hand underneath.  

2. How To Loosen A Treadmill Belt 

If your treadmill starts to jolt or the belt is slipping when you’re running, it may be too loose. Lift up the belt from the center, and if it goes higher than 3-4 inches, it's definitely too loose. You’ll then need to follow these steps.  

  1. 1
    Disconnect The Treadmill   
    Again, make sure everything is turned off and all power supplies are disconnected.  
  2. 2
    Find The Roller Bolts    
    Find the two roller bolts on the back on the treadmill. 
  3. 3
    Tighten The Treadmill Belt   
    Use your wrench to tighten each bolt by turning them right, one quarter turn at a time. Ensure you do both bolts (so tighten the right bolt, then the left bolt each time) and keep going until you feel it tighten. 
  4. 4
    Check The Belt  
    If the belt is tight enough now and only lifts 3-4 inches from the deck, then the problem is solved.    

3. How To Align A Treadmill (Left Or Right)

  1. 1
    Disconnect The Treadmill    
    Completely disconnect the power source and pull out the cord to make sure it’s switched off.    
  2. 2
    Work Out The Direction     
    Check the belt to see which way it’s moved. This will determine which side you need to work on. 
  3. 3
    Adjust The Roller Bolt    
    Roller bolts are located on the back of the treadmill, one on the left and one on the right. If the belt has moved to the left, use your wrench on the left rear roller bolt. If it's moved to the right, then use the wrench on the right rear roller bolt. Tighten until the belt has gone back to the center.  
  4. 4
    Check The Treadmill   
    Plug everything back in and check the treadmill belt to make sure it’s in the right place and moving correctly.  
Adjusting Treadmill Belts

People Also Ask (FAQs)

How do you tighten the belt on the Proform treadmill? 

To tighten a Proform treadmill belt, you’ll need to follow the steps above but make sure you use an Allen wrench to tighten the bolts. Proform is a good quality brand and should have easy to follow instructions. 

How to tighten a Nordictrack treadmill belt? 

A NordicTrack treadmill belt uses idler bolts which are basically the same as roller bolts we described in this guide. Simply tighten both bolts equally to tighten the belt. Nordictrack is a high-quality treadmill manufacturer, so their instructions should be pretty easy to follow. 

How do you test a treadmill belt? 

You need to test a treadmill belt to make sure there’s not too much or too little friction. The best way to test it is to stand on it and move up and down to see if it moves with you a little. You should also be able to hold the handles and walk on the treadmill pretty easily without any difficulty. 

You can also feel underneath the center of the treadmill belt. It should feel smooth so that the belt can glide over it.  

Why does the belt on my treadmill move to the side? 

If your treadmill belt is moving side to side, it means it needs to be recentered and tightened. Make sure both roller bolts are equally tight, so it doesn't lean to one side. 

When should I replace my treadmill belt? 

The biggest sign you need to replace your treadmill belt is if it’s become noticeably damaged. Look for frayed edges and loose threads, which indicate the belt needs to be completely removed and replaced. Your treadmill belt should last for about 300-500 hours of us, which is generally about 3-5 years, and after this, it should be replaced.  


The belt is one of the most important parts of a treadmill, and it’s essential to keep it in good condition. Some people think as soon as there’s an issue with the treadmill belt, then they need to replace the whole machine, but in reality, it’s really easy to sort yourself.

Hopefully, this guide has given you a clear explanation of tightening a treadmill belt and giving you the confidence to do it whenever you need to.  

Last Updated on January 25, 2023

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Andrew White

Andrew White is the co-founder of Garage Gym Pro. As an expert fitness professional (gym building nerd) with over 10 years of industry experience, he enjoys writing about everything there is to do with modern fitness & the newest market innovations for garage gyms. When he isn’t testing out products for his readers, he’s usually out surfing or playing basketball.