Age:
Weight (kg):
HR:
Sex:
VO2max (optional):


This is based on the following formula which was found in a paper titled "Prediction of energy expenditure from heart rate monitoring during submaximal exercise" by L. R. KEYTEL, J. H. GOEDECKE, T. D. NOAKES, H. HIILOSKORPI, R. LAUKKANEN, L. VAN DER MERWE, & E. V. LAMBERT that was published in the Journal of Sports Sciences. I also found that Polar cites this paper as a source for their OwnCal(TM) calculation. They also cite a bunch of other studies. The formula for calculating energy expenditure in this article uses all of the factors that Polar says they use. So this may or may not be the formula they are using. Here are the formulas adjusted to Calories and separated into gender specific formulas:

Using VO2max
Men: C/min = (-59.3954 + (-36.3781 + 0.271 x age + 0.394 x weight + 0.404 x VO2max + 0.634 x HR))/4.184
Women: C/min = (-59.3954 + (0.274 x age + 0.103 x weight + 0.380 x VO2max + 0.450 x HR)) / 4.184

Without VO2max
Men: C/min = (-55.0969 + 0.6309 x HR + 0.1988 x weight + 0.2017 x age) / 4.184
Women: C/min = (-20.4022 + 0.4472 x HR - 0.1263 x weight + 0.074 x age) / 4.184
weight is in kg