I measured my resting heart rate using the runtastic chest strap and It is 54. I am 27 years old and my current weight is 75 kilograms (165.3 lb).
I used the Formular which according to wikipedia was the least objective to get my max heart rate:
205.8−(0.685×27) = 187.305
With this data Runtastic calculated the following heart rate zones:
Easy: 120 - 132 Fat Burning: 133 - 146 Aerobic: 147 - 159 Anaerobic: 160 - 172 Red Line: 173 - 187
But according to this image on wikipedia which uses the fox and haskell formula, my fat burning rate should be approximately 115 - 135 which is totally incoherent with the zones calculated by runtastic.
What is going on here? I know that it is not possible to say it with absolute precision, but what would my fat burning zone approximately be?