TR kJ/Cal calculation suprisingly low

For me tracking energy intake and expenditure is what works. It has taken me 50 plus years to realize it but I have been very succesful with getting fit using tracking. It has been an absolute life changer and I would recommend it to anyone struggling with any type of weight issue. Before I open up a huge can of worms I will say that if I have learned anything it is that everyone is different and each person has to find a sytem that works for them. Another thing I have also discovered is that depending on the app, website, program, or computer you use the calculations for calories burned can be substantially different from program to program. I have spent a fair amount of time comparing various calulators and usually take 2 or 3 and average them to get a more accurate result. ALL of them including TR have metrics to plug in your height, weight, age etc for the record so it should be comparing apples to apples so to speak. With that being said the values that TR shows are the lowest I have seen ANYWHERE. For example a regular app I use has the amount of calories burned for TR Baxter @ 90 mins is 1130. TR shows 740, Cycling. com 1078, and the list goes on and on. Most are in the 1000ish or a little higher range for my metrics. Point here is that TR values seem to be low to the extreme side. For those who don’t track or don’t care to track this is moot information but for those that do I’m interested in your thoughts.

TR uses power to measure kJ (power * time), and converts that into calories. The calories reported are the calories consumed just by the workout, and do not include the calories consumed by your underlying metabolism.

I don’t know the approach used by the other calculators you mention, so can’t comment on them specifically. But other calculators may not use power, may use heart rate, and may also include calories consumed by your metabolism. These all contribute to reasons why other calculators over-report workout calories

There can also be differences in the body mechanical efficiency assumed by different calculators (I think TR is about 23%)

The TR algorithm IMO is the most accurate approach for calculating calories from workouts - power only; no heart rate; exclude calories for underlying metabolism.


What is the kj number from your power meter?

Sounds about right , baxter at 250FTP is 875KJ/Kcal.
Apps like myfitnesspal and most others just give a “feel good” estimate and will spit out crazy numbers like 700Kcal for an hour at 24kph. Or 1000Kcal for an hour of regular swimming.

The most accurate way is to just measure output Like TR does and add that to your BMR.

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Seperate power meter isn’t set up on the trainer bike. It’s a smart trainer (Kickr core) and it’s tied to TR so it shows TR values. On other apps I go by time spent and speed range with my metrics plugged in.

Then you’re comparing an educated calculation (TR) with pretty much an educated guess (the others). Time spent and speed range carry way too many variables to create a reliable number.

There’s a good blog from the TR guys explaining the calculation here:


Yes I have also heard that many of the apps calculate high for a “feel good” result. The only issue with that is most of them are in the same range or ballpark where as TR shows more than 25% less. In addition using an average of some of the apps has produced stellar results for me personally so I’m on the fence about them being WAY too high. TR may very well be more accurate and it’s only to my advantage since it will force me to cut my intake to match.

Nuff said, the numbers you’re getting from TR are the correct ones.

Unlike every other app you’re using, TR is actually measuring power, not estimating. Power and energy expenditure are very tightly correlated and there’s little to no room for interpretation.

The only case where your numbers might be way off is on a dumb trainer with no power (using Virtual Power).


The main reason calculators go wong is that they assume metabolic efficiency is a fixed % when it varies very considerably, not least related to the fitness of the individual. So whilst the basal metabolic rate estimate might be about right (based on height/ weight/ gender), the exercise related bit is wrong. We looked at a lot of factors when making our calculator (including but not limited to working out the equations for metabolic efficiency vs FTP). bw alex


This could be due to increased metabolic rate after exercise.

So you burn 750 kCals during the workout, but your metabolic rate is increased so you burn an extra couple hundred throughout the rest of the day.

TR and power based apps are designed for accuracy and thus cannot/will not predict something that may vary wildly among different people.

So you could be getting “lucky” with the other apps, where the overestimation of calories burned during the workout just happens to correlate closely to the sum your actual calories burned during the workout PLUS the extra calories burned during recovery.

For other people, it may be way off, and could result in overeating and weight gain.

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Yep. Also varies men vs women, and vs the exercise intensity.

At the end of the day, the most important question is why you want to know calories consumed. If for weight loss, the best evidence will be the scale - as over the period of weeks/months of an exercise/diet program, if it’s working the scale will say so, regardless of what calorie counts may say.

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This right here is the case. I also use an Apple Watch during my workouts and the AW ‘active calories’ and TR reported are pretty dang close.

I asked 4 guys at the bar and they all disagreed with the expert that’s my problem with the expert’s answer


Most other posts are correct including the reference to the TR blog post - calories burned calculated as an estimate from power is far more accurate than HR based estimates or height/weight/distance calculations. Some apps used to provide an estimate purely on distance (ignoring work completely).

Imagine coasting down a hill for 10 miles casually without putting any power. You really don’t burn any calories outside of metabolic losses, but a simple calculation of height/weight/distance would possibly claim a 500 calorie burn. This is a contrived extreme example but just tries to get the point across. It’s not even a criticism of the other sites, they have too little information to give very accurate results.

I think any training app / power meter / garmin or wahoo bike computer will show you very consistent calorie estimates when used with a power meter and they will be very close to the TR number.


TR is high on my trust radar. Garmin (without power meter and HRM) gives the wildest calorie expenditure and is lowest on my trust radar. Paired with HRM and PM it gives similar results to TR

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This is the answer. I used to wonder why long rides would be over by 1-2000 calories when using the same GPS file with heart rate data on certain websites/apps - the answer is that some apps add the calories you’d be burning anyway, so if you exercise for 12 hours and your BMR for a day is 2000, it’ll add 1000 on to the ‘calories burned’.

TR will give you the number of calories that you burned on the bike, accurate to one of the highest levels possible (as cycling is an activity that’s relatively easy to measure output for)

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You are way overestimating the “afterglow effect.” It is so small that you might as well ignore it, at least when talking about estimated calories burned.

I don’t think I am.

It’s a debated topic. You’re welcome to believe whatever you want.

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Yes, you are.

Science >> belief.

It’s very difficult to measure post exercise calorie burn in the lab, because subjects have to be willing to spend basically a day in the lab to do the exercise, then proceed with normal living for the duration after.

So there’s not as much studies on this, as say VO2 max.

Here’s one study where post exercise calorie burn over the 14hrs post exercise was an additional 37% of the energy expended during exercise.

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