If you are healthy and generally fit you can self-test for your recorded max heart rate. I used the 220 minus age and Karvonen formula for 2-3 months. Kept bumping up against my upper limit and was afraid to go beyond it. After discussions here and with a nurse, decided to go with the recorded max to set my HR zones. During my annual checkup the doc concurred. In the absence of other risk factors (poor fitness, family history, cholesterol numbers, blood pressure) he felt it was fine to used max recorded HR instead of some formula.

Summary: Start with a formula for safety and see how that works for you. If you feel that your actual max HR is higher then work your way up to it. Have fun while getting there.