'''There are three simple methods to determine the hart frquency (HF):'''
# Count the small (1mm) lines between two QRS-complexes. Hens, the ECG paper runs with 25 mm/sec through the ECG writer, therefore: [[
Afbeelding:HFformule.png]]This method work fine in case of tacycardia (>100 beats/minute)<br>
# To determine the frequency of a normal sinus ritme: Use the sequence 300-150-100-75-60-50-43-37. Count from the first QRS complex, the first thick line is 300, the next line 150 etc. Stop the sequence at the next QRS complex. When the second QRS complex is in between two lines, take the mean of the two numbers from the sequence. You can finetune this method with the following more precise sequence: