Forerunner 305: HRM and Calories Query

Hi All

Love my Forerunner 305 and I use the HRM function. Two weekends ago I did a 20 mile hike, mostly around canals and generally flat with only a small hill involved, it said i burned about 2000 calaries which seemed about right as I'd hardly seen my hearbeat go above 105.

However this weekend I did another 20 mile hike, this time with 2800ft of steep hills, and every step was battling mud and i don't think my HR dropped below 130 at any point. It said I burned 2000 calories. At the very start of the walk I spent ten minutes climbing up a very steep hill (at least 45%) and it gave me calories burned of 35. Now I know my HR was similar to running during this time and would have expected to see 200 at least burned, similar to my old HRM which was an ALDI cheap job.

Does the Forerunner calculate calories burned using the HRM at all? Or is it all based on the distance travelled? My two similar lengh hikes at varying effort levels would say that it only takes distance into account.

Anyone know or how to make it use the HRM to calculate calories burned?



  • I don't think it takes into account the HRM. I have a 205 which doesn't have one but is very similar. I think it might take into account your weight but I am not sure.
  • I think it does a weight v distance v time calculation.  It is not accurate.  If you upload your data into sporttracks you will get a more accurate assessment. 
  • I dont think it takes into account heart rate. I two hour fell runs comes out the same as two hours on flat roads. Definately not right. I suspect its fairly accurate for road running, but is under estimating for fell runner and over estimating for cycling.
  • Thanks I figured as much, it always seems about right for the roads. There's no massive point me wearing the HRM part then as I don't really need to know my HR on route.

    Does Sportstracks calculate it properly then?


  • I doubt you will find any program that can calculate specific calorie burning rate, as there would be too many parameters involved.  A general rate can be given with your height/weight data calculated against time/distance, as this will provide enough information to calculate how much work you've done.  However your personal details, such as your muscle/fat ratio, your metabolic rate, how hydrated you are, the timing of your workout (morning vs evening), even how much caffeine is in your system, are going to affect the speed your body burns calories, and make a calculation pretty much impossible, IMHO.

    I'd love to be wrong tho!

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