# Calories burned according to a Garmin...



## npoak (Dec 14, 2006)

I recently started training with a Garmin forerunner 305, for both cycling and running. I've spent some time with the data over the past week or so and so far everything seems to be where it should be (it's always a pain to vest out a new training device to make sure it's numbers are correct). One thing has struck me as a bit off though, it's not even something I care about but found it interesting. The calories used/burned number.

On a recent ride of 24.4 miles (4 laps of the full loop in central park) in around 1h16m on a 46x16 fixed gear with an average cadence of 86, an average pace of 19.8 and an average bpm of 130. the Garmin says I burned close to 3000 cal. I am a 190 pound 32 year old male. That calorie burn seems very high to me. All the other numbers though are what I would expect.

Again, calories burned isn't a number I'm that interested in but still I found how large this number was interesting. I'd expect it to be around 1000 cal or there abouts, not 3000. Are the Garmin f305's calorie burn numbers known to be off? If not what does it use to figure that?


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## Dwayne Barry (Feb 16, 2003)

npoak said:


> Again, calories burned isn't a number I'm that interested in but still I found how large this number was interesting. I'd expect it to be around 1000 cal or there abouts, not 3000. Are the Garmin f305's calorie burn numbers known to be off? If not what does it use to figure that?


Yes that is a unrealistic number. The most powerful cyclists in the world can only work hard enough to burn roughly 1500 cal/hour. So even in two hours they would have a very hard time to burn 3000 calories.


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## npoak (Dec 14, 2006)

Dwayne Barry said:


> Yes that is a unrealistic number. The most powerful cyclists in the world can only work hard enough to burn roughly 1500 cal/hour. So even in two hours they would have a very hard time to burn 3000 calories.


ya, right? So what could have caused this? Is the Garmin just always off at this data point or is there a configuration I over looked?


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## Bianchiguy (Sep 8, 2005)

Did you enter your personal profile information during set up? Sex, age, weight?


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## npoak (Dec 14, 2006)

Bianchiguy said:


> Did you enter your personal profile information during set up? Sex, age, weight?



Yes, that is why I pointed it out in my OP.


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## Bianchiguy (Sep 8, 2005)

Well, I just completed a century ride over this past weekend in mountainous terrain. With a 6.5 hour ride time, my 305 calculated I burned something like 6500 calories. That sounds reasonable to me, but who knows.


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## SilasCL (Jun 14, 2004)

Unlikely. More like 700 calories an hour, not 1000.


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## Dwayne Barry (Feb 16, 2003)

Bianchiguy said:


> Well, I just completed a century ride over this past weekend in mountainous terrain. With a 6.5 hour ride time, my 305 calculated I burned something like 6500 calories. That sounds reasonable to me, but who knows.


Well you can make reasonable estimates. How fit are you? 1000 calories per hour would be quite a high work rate, maybe even pro-like numbers, that's probably an average of ~300 watts. Many well-trained cyclists can do that for an hour but for 6.5 hours?


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## tcruse11 (Jun 9, 2006)

I think you have to take your weight into consideration. You are considerably heavier than most pros (not to bash you, I weight 190 as well). Pros weigh about 165 (?) pounds on average. If I'm not mistake, which I may be, the heavier you are the more calories you burn at a given intensity compared to someone who is lighter.


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## SilasCL (Jun 14, 2004)

tcruse11 said:


> I think you have to take your weight into consideration. You are considerably heavier than most pros (not to bash you, I weight 190 as well). Pros weigh about 165 (?) pounds on average. If I'm not mistake, which I may be, the heavier you are the more calories you burn at a given intensity compared to someone who is lighter.


Sorry, but no. If you're bigger, at the same speed you'll be burning more calories than someone smaller. At the same intensity (by which I will assume power) you'll be burning the same amount of calories.


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## tcruse11 (Jun 9, 2006)

SilasCL said:


> Sorry, but no. If you're bigger, at the same speed you'll be burning more calories than someone smaller. At the same intensity (by which I will assume power) you'll be burning the same amount of calories.


That makes sense. So at 20 mph the heavier rider burns more calories than the lighter rider. However at 200 watts they both burn the same amount of calories. ????


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## SilasCL (Jun 14, 2004)

tcruse11 said:


> That makes sense. So at 20 mph the heavier rider burns more calories than the lighter rider. However at 200 watts they both burn the same amount of calories. ????


Exactly. One caveat, on flat ground, they'd be burning pretty similar amounts of calories, with aerodynamics playing a larger role than weight.

But power is power, and that will determine calories burned. Of course each person is a bit different in efficiency, i.e. how many calories they burn in putting out a certain amount of power, but this is a relatively small range.


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## tcruse11 (Jun 9, 2006)

I just plugged your stats into a calorie calculator at bikejournal.com and it says you burned 1,669 calories.


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## npoak (Dec 14, 2006)

Hmm, interesting info here. Thanks. Like I said. I'm not concerned with calories burned, just was curious.


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## Wookiebiker (Sep 5, 2005)

It sounds quite high actually...

My general numbers, I'm 230 pounds and a decent cyclist with 20ish % bodyfat currently. If I go out for a hard effort where my average HR is in the low-mid 140's I burn about 1000 calories per hour.

Looking at the speeds I ride on the terrain I ride, I generally can sustain around 290-310 watts of power which puts my caloric burn pretty close to correct (I use a Polar HR monitor to keep track of my caloric burn).

On a century I did this past weekend with just over 4400 feet of vertical climbing and 102 miles ridden I burned just over 5800 calories completing the century right at 6 hours averaging 16.9 mph.

The reality is you are probably closer to 900-1000 calories.


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## Bianchiguy (Sep 8, 2005)

What about effort? A ride of the same duration on relatively flat ground vs one with say, 6000 feet of climbing?


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## Bianchiguy (Sep 8, 2005)

I guess Garmin needs to tweak their calories burned estimator:idea:


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## zeeke (Aug 22, 2006)

Its a long standing issue with the garmin, it calculates calories based off of heart rate and distance/time. Its way way off, right at 50% most of the time.

If you use sport tracks and then hit the calcuate button on each activity it gets a little closer to the real ballpark. Plus its a better diary type program anyway keeping up with daily/weekly/monthly stats etc with full maps and stuff. It has its share of bugs though.


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## Argentius (Aug 26, 2004)

*not a chance...*

Your insticts are right, that's not a realistic number at all. Most calorie counters seem to overestimate by a quarter or a third, I think because they underestimate the efficiency of a road bike.

But, that number is like triple the realistic result. Perhaps your data have artifacts? Sometimes, my garmin has given me temporarily screwy results, like a 4,000' climb in 1 mile in the middle of my ride. That would probably mess up the calorie count...


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## npoak (Dec 14, 2006)

zeeke said:


> Its a long standing issue with the garmin, it calculates calories based off of heart rate and distance/time. Its way way off, right at 50% most of the time.
> 
> If you use sport tracks and then hit the calcuate button on each activity it gets a little closer to the real ballpark. Plus its a better diary type program anyway keeping up with daily/weekly/monthly stats etc with full maps and stuff. It has its share of bugs though.


I'm a mac guy. I'm using the motionbased.com log, though for some reason that changes some of the values to things. The data is on par on the device itself but for some reaosn motionbased.com changes the time, distance and messes up some of the speeds here and there....it seems totally random too.

I use a paper riding journal anyway, the garmin gives me the data points I want so I leave it at that.


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## Brad2021hk (Nov 23, 2005)

Sounds more like the number of calories burned running rather than cycling over 26 miles. Maybe it uses distance and weight to calculate calories burned in a run more than time and heart rate. The Forerunner is marketed to runners.


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## parity (Feb 28, 2006)

forums.motionbased.com has everything you need to know about the edge 305. The answer to how it calculates the calories burned is by speed, weight & time:

http://forums.motionbased.com/smf/index.php?topic=4325.msg26968#msg26968


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## asgelle (Apr 21, 2003)

npoak said:


> Are the Garmin f305's calorie burn numbers known to be off?


I've ridden with a Forerunner 305 along side a Power Tap. The Garmin calories burned is off by around a factor of 2,


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## Touch0Gray (May 29, 2003)

hey guys, not a 305 user but I am a garmin user. I've said it before and I will repeat it over and over and over. If you have a question/problem with Garmin....hardware/software/frimware...call them. They have the best customer service I have ever had the opportunity to deal with.
If their units are wrong they WANT them to be accurate and will do their best to upgrade the firmware. That said there is a firmware update as of yesterday (June 6,2007)
Seriously, call Garmin...they are great.


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## redjeepjamie (Mar 29, 2007)

*calories burned way off*

I am 6'2" 195 last night I did 22 miles at an average pace of 18.2 and bpm average of 152 and the 305 had my calories at just 1134. Last Sunday I did 71 miles and at 15.5 and only burned 4568. maybe your hight and weight are of in the Garmin user data.


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## npoak (Dec 14, 2006)

asgelle said:


> I've ridden with a Forerunner 305 along side a Power Tap. The Garmin calories burned is off by around a factor of 2,



That is what I wanted to know. Thanks!


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## rbmn9529 (May 13, 2006)

My Edge 305 gives me a higher calorie burn than my Polar F6 did. Even with the correct bio info entered


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## GaryJaz (Sep 21, 2005)

I think Garmin changed the way the Edge computes calories expended in one of their updates recently. I know that I'd burn a lot of calories going downhill before, but now the Garmin Trainer app is showing that I'm not. I don't recall an announcement for the change. Anyone else notice this?


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## pushing_tin (Feb 11, 2007)

I have and Edge 305 and a Forerunner 305. This has been a complaint of mine since I bought them. From what I know neither of them take your heart rate into the calories burned calculations. IMO this would go a long way in making the estimate (it is just that) more accurate.


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## estone2 (Sep 25, 2005)

pushing_tin said:


> I have and Edge 305 and a Forerunner 305. This has been a complaint of mine since I bought them. From what I know neither of them take your heart rate into the calories burned calculations. IMO this would go a long way in making the estimate (it is just that) more accurate.


Would it?

I know a friend of mine was slaughtering themselves today, heart rate at 180, to pump out 200 watts.

My heart rate was 145.


That doesn't help any unless there's an established fitness level.


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## NomadVW (Jun 30, 2006)

pushing_tin said:


> I have and Edge 305 and a Forerunner 305. This has been a complaint of mine since I bought them. From what I know neither of them take your heart rate into the calories burned calculations. IMO this would go a long way in making the estimate (it is just that) more accurate.


Actually it would do absolutely nothing to make the estimate accurate. Heart rate will not = work being done universally. Seems the Garmin's could do a good job using speed and their % gradient with known weight to determine a power estimate similar to that of analyticcycling or kreuze.... ors' (sp). Weight, speed and % grade are useful. HR is not useful.


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## scottmilk9 (Jul 31, 2006)

I biked yesterday, 26miles, but much slowe pace than you, i avg about 13mph with stops and everything, we rode in a no drop group, so we regrouped a couple times and with stop lights, my 305 said i burned 1400calories. With a fixed gear and higher cadence, its possible.


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## pushing_tin (Feb 11, 2007)

I found this reply on the motion based forums.



> The Forerunner calorie calculation is roughly based on the formula
> 
> Energy = Mass * Distance
> 
> ...


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## bleckb (Jun 13, 2005)

*garmin overshoots*



npoak said:


> Hmm, interesting info here. Thanks. Like I said. I'm not concerned with calories burned, just was curious.


My experience is that the Garmin overshoots the calories burned, sometimes by a huge amount. I use fitday for calories, food tracking and such and it always comes in low. I don't know why the Garmin comes in so high some times, but when it says I'm burning 2000 calories in 45 minutes sometimes, I know it's whacked. I suggest finding some other software to track calories consumed and burned and work with that number if you want to have a reasonably accurate sense of things.


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## BigDaddySmooth (May 21, 2004)

I recently purchased a Polar HRM with a calorie counter. It correlates about 99% of the numbers I get from a treadmill so there must be a standardized formula out there somewhere. I just ordered the Garmin forerunner 205 so it is going to be interesting to compare hte calories w/my HRM and the average speed with my cycle speedometer and distance w/my car odometer. Isn't geekdom great?

3000 calories per hr is probably far off for about 200 watts of power you generate riding at 20 mph (unless therewas a 30 mph headwind ;-)). The best pro's in the world doing any aerobic sport (cycling/running/X-C skiing, etc) probably burn 2000 cals per hour at max effort (eventhough the effort may be much shorter duration than an actual hour).

A puny guy like me weighing 140's and running at 8 mph = about 900 cals an hour so there is no doubt the numbers only go up for larger/faster people.


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