Count the number of large squares between two consecutive R waves and use 300 ÷ number of large squares
Count the number of small squares between two consecutive R waves and use 1500 ÷ number of small squares
Count the number of QRS complexes in a 6-second strip and multiply by 10
Use the sequence 300, 150, 100, 75, 60, 50 for R-R intervals spanning 1 to 6 large squares
For irregular rhythms, use the 6-second strip method
For regular rhythms, use the large-square or small-square method