If you are among those who constantly worry about how many calories you burn, you’ll learn two important ideas in this article:

  1. You can’t trust estimated calorie burn on cardio machines, because they are likely inaccurate, and
  2. Worrying about calorie burn is not the path towards fitness success over the long term

Here are 3 reasons why estimated calorie burn on cardio machines is likely inaccurate:

Reason #1 – Estimated Calorie Burn Includes Your RMR

Everyone has a unique amount of calories they need to ingest to maintain their body weight. This is referred to as your resting metabolic rate (RMR), meaning that if you lay down all day and didn’t move you would still be burning calories just by being alive (breathing, organ function etc.) Your RMR is a huge determinant of how many calories you need to consume each day.

Treadmill and other cardio machines include RMR within their calorie estimates. So the calorie estimate you see on display is not just how many calories you have burned during your activity, but also how many calories you have burned just being alive during that time. This leads to an over inflation on how many calories you burned from exercise.

For example, if a 175 lbs man exercises for a half hour at a moderate pace, he will burn around 270 total calories…according to his machine. For an accurate count, he’d need to subtract around 40 calories from the 270 for the calories he used just by being alive for the half hour.

The greater your workout time and the heavier you are, the more overinflated the number becomes. If you rely on exercise to create a large caloric deficit, you’ll want to consider this over estimation.

Reason #2 – Cardio Machines Assume You Are A 180lb Man

Calorie estimations are very difficult because individuals vary so widely. In order to correctly estimate caloric expenditure, many factors need to be considered: total energy cost of exercise depends on weight, gender, age, height, amount of muscle, and disease state.

Treadmills rarely take the aforementioned into account. If you are exercising on a cardio machine and fail to give it any input such as your height, weight, or age, your estimates will be very off. The cardio machine will use a default runner based off a typical man weighing 160-180 lbs. If you weigh less then a typical man your calorie estimates will be over inflated, and vice versa.

Reason #3 – Cardio Machines Do Not Take Into Account Exercise Efficiency

Efficiency can be described as how easily your body uses calories to do work. Someone who is highly efficient would be able to do more exercise using fewer calories.

There are many factors that effect exercise efficiency1 that may also throw off the estimated calorie burn shown on a machine:

1. Muscle Fiber CompositionFast twitch fibers are less efficient then slow twitch fibers. Thus your efficiency and potentially calories burned will depend on your genetic disposition and your overall training history.

2. Exercise Technique – Improved technique produces fewer extraneous body movements and increases efficiency.

Take for example, a competitive swimmer vs. a person who rarely swims. If asked to travel the same distance at similar speeds, the experienced swimmer would burn less calories due to smoother strokes and an understanding of buoyancy that make the activity require less effort.

The same applies to cardio machines. Although they are less technical then swimming those who improve their form will have different energy cost then those who are unfamiliar.

A relevant example is holding up your body on the handrails on a machine like the Stairmaster. Bracing yourself with your arms makes the activity easier, yet the machine fails to adjust for this measure.

3. Fitness Level – More fit individuals perform a given task at a higher efficiency because of decreased energy expenditure from non-exercise tasks such as temperature regulation, increased circulation, and waste removal.

The above is not meant to bash using cardio machines in your quest to lose fat. Increasing efficiency is not necessarily a bad thing for fat loss. With an increase in efficiency also comes with an increase in ability. More efficient exercisers can push themselves harder.

In fact, best fat loss practices encourage you to increase the intensity of your cardio workouts, not necessarily the duration.

How Do You Accurately Estimate Calorie Burn From Exercise?

Over all, there’s too much variation to get an accurate estimation of how many calories you burned if you rely on the number calculated by a cardio machine. If you really need the number of calories burned, it may be more accurate (and more time consuming) to calculate manually, or to rely on a calorie burn tracker like BodyBugg, which has its own limitations.

At the end of the day, it is important to get your diet in check so you don’t have to rely on the “burn it off” mentality. Understand that no amount of exercise will get you shredding fat if you’re not maintaining it with a proper diet. Attempting to out-exercise a bad diet is a losing proposition.

Consider weight training, followed by interval training, as your preferred method of burning fat. Throw in steady state cardio if you don’t want to limit your workout to strength training, but remember…don’t trust the machine.

If you’re serious about losing weight, check out these 101 Proven Tips to Lose Weight Fast.



  1. Alexander Mar 04, 2013 - 23:25 #

    Once again, thanks for the advice given. I didn’t know about reason #1 previously.

  2. warren Mar 06, 2013 - 08:19 #

    A very informative article, when it comes to loosing weight and tracking your process counting calories burned was very important to me.

    I was counting the calories I eat and also the calories I burn, the reason for this was that I would eat back maybe half or all of the calories burned. In the beginning it seemed accurate and was working as I was shedding the fat, dropping pounds and my BF% was dropping.

    Where it starts to get difficult is when you hit the dreaded plateau. After tinkering with my diet and trying to accurately calculate my burn I noticed that if I tighten up my diet and record calories I eat more accurately and not bother with eating back the burned amount I will continue to drop the pounds and BF.

    So far I dropped 21lbs and reduced my bf% by 8% however I’m finding it harder at this moment in time to keep up with dropping 2lbs a week. I have continued to increase the intensity of my workouts and changed them up and my bf% seems to keep going down (if I trust the machine which calculates it for me.)

    This website has played in big part in educating me to do and eat the right things…

    Keep it up!

  3. Patrick Koch Mar 06, 2013 - 09:30 #

    Warren, congrats on the hard work.. In my experience weight loss is rarely linear. You are taking all the right steps though. Keep arming yourself with knowledge. And I’m glad Builtlean has helped.

  4. Krassi Mar 06, 2013 - 20:08 #

    Thank you Pat for the light brought to this always disputable gym matter.
    I knew that the treadmills were not accurate because each one (different model) gives me different readings for the same exercise, but so are the bicycles.
    Not that I really bother how much calorie I burn, but I need to track and measure somehow my exercises.
    What do you think about the heart rate monitors? Are they any closer to the truth?
    Thank you again.

  5. Patrick Koch Mar 07, 2013 - 23:06 #


    I have had trouble finding information on the formulas the heart rate monitors use. My intuition tells me they are slightly better but its hard to say. This could be a good question to ask a company rep.

  6. Krassi Mar 08, 2013 - 13:17 #

    Thanks Pat,
    I also have the feeling that they might be a bit better indicator, but what I found strange is when I do moderate cardio I hardly break a sweat, but my heart rate is 140/150. When I do streingth training I hardly breath and my sweat runs like a river, but my heart rate is 120/130.
    I do not think I burn more calorie keeping the treadmill turning.
    Thank you for the article and for the advice. I will check with Suunto rep here about the formula.

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