How to Calculate Heart Rate for Irregular Rhythm

Irregular Heart Rate (BPM) Calculator

Designed for Atrial Fibrillation and Arrhythmias

Number of Beats Counted (QRS Complexes): Count the pulses or R-waves on an ECG strip during the observation period.

Observation Duration (Seconds): 6 Seconds (Standard Method) 10 Seconds (More Accurate) 15 Seconds 30 Seconds 60 Seconds (Full Minute)

Estimated Heart Rate:

0 BPM

Calculating a heart rate when the rhythm is irregular (like in Atrial Fibrillation) is different from calculating a regular pulse. In a regular rhythm, you can simply measure the time between two beats. In an irregular rhythm, the interval between beats (the R-R interval) changes constantly.

The 6-Second Method

The most common clinical technique for irregular rhythms is the 6-second method. This provides an average heart rate over a specific period rather than a momentary snapshot.

Step 1: Obtain a 6-second strip (on an ECG, this is usually 30 large boxes).
Step 2: Count the number of R-waves (the tall peaks) within that 6-second window.
Step 3: Multiply that number by 10 (since 6 seconds x 10 = 60 seconds).

Why Accuracy Matters

If you only count for 10 seconds and multiply by 6, a single missed beat can change your calculation by 6 BPM. For highly irregular rhythms, counting for a longer duration (like 15 or 30 seconds) provides a more stable average.

Observation Period	Multiplier
6 Seconds	x 10
10 Seconds	x 6
15 Seconds	x 4

Example Calculation

Suppose you are looking at a 6-second ECG strip for a patient with AFib. You count 9 R-waves (peaks) within those 6 seconds.

Math: 9 beats × 10 = 90 BPM.

Irregular Heart Rate (BPM) Calculator