Ecgboxes to Seconds Calculator
Calculate ecgboxes seconds quickly with our cardiovascular system tool. Get results based on evidence-based formulas with clear explanations.
Reviewed by Rahul Singh, Health & Wellness Specialist
Formula
Time (seconds) = Number of boxes x (box size in mm / paper speed in mm/s)
At standard 25 mm/s paper speed, each small box (1mm) equals 0.04 seconds and each large box (5mm) equals 0.20 seconds. Heart rate can be calculated as 60 divided by the R-R interval in seconds.
Worked Examples
Example 1: Converting R-R Interval to Heart Rate
Problem:An ECG shows 3 large boxes and 2 small boxes between consecutive R waves at standard 25 mm/s paper speed. What is the R-R interval in seconds and the heart rate?
Solution:Total small boxes = (3 large x 5) + 2 small = 17 small boxes\nTime per small box at 25 mm/s = 1mm / 25mm/s = 0.04 seconds\nR-R interval = 17 x 0.04 = 0.68 seconds = 680 milliseconds\nHeart rate = 60 / 0.68 = 88.2 bpm
Result:R-R interval: 0.68 seconds (680 ms) | Heart Rate: 88 bpm
Example 2: Measuring PR Interval Duration
Problem:A PR interval spans exactly 4 small boxes on a standard ECG recording at 25 mm/s. Is this within normal range?
Solution:PR interval = 4 small boxes x 0.04 seconds = 0.16 seconds = 160 milliseconds\nNormal PR interval range: 0.12 - 0.20 seconds (3-5 small boxes)\n0.16 seconds falls within the normal range\nThis indicates normal AV conduction time
Result:PR interval: 0.16 seconds (160 ms) | Status: Normal PR interval
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy