ECG Boxes to Seconds Calculator

ECG is a simple cardiac test to check the cardiac rhythm and the heart’s electrical activity. There are different sensors that are connected to the skin to identify the electrical signals produced by cardiac activity in the form of heartbeats. Electrocardiograms are in the form of boxes and signals. It is quite difficult for a person to interpret the ECG segments.

This article explains the basic details of ECG boxes to seconds calculator. It is an easy tool to convert the ECG segments into seconds to easily grab the details of ECG. In addition, it is also helpful for physicians to discuss the abnormalities associated with ECG segments. This calculator will convert the length of ECG intervals into seconds or milliseconds. In this way, it makes it easy to understand even the minor details and other abnormalities related to the ECG.

How can we measure ECG boxes?

Calipers are the most recommended method to measure the ECG boxes between the two standard points on the electrocardiogram. Here is the following method to measure ECG boxes on an electrocardiogram.

  • Put the measuring tip of one of the calipers at the first point, which is the initial point of the P wave.
  • Put the measuring tip of the caliper at the second point. Do not change the position of the caliper tip at the first point.
  • Pick the caliper up without changing the angles between the measuring tips of the caliper.
  • Place the first measuring tip at the starting point of an ECG box. Put the second measuring tip in a way to maintain a horizontal distance between the two measuring tips.
  • Count the overall number of boxes between these two caliper tips. In this way, you can easily get to know about the ECG boxes.

How can we convert the ECG boxes to seconds?

There are two box patterns on the electrocardiogram. One is the small box and the other one is the large box. Every small box in the ECG measures a segment of 1mm. Whereas, the big box adds a length segment of about 5mm. Both these boxes denote different time duration depending on the speed over the paper set in an ECG machine.

The overall speed on the paper set is about 25 mm/second. It is one of the most common speed values used in most cases. It means that with the passage of every small box on the X-axis, a time interval of 0.04 seconds passes. In contrast, every big box counts for 0.2 seconds. These are the standard values for a paper speed of about 25 mm/second. As the speed of the paper set in the ECG machine increases, the time duration of every box decreases.

Let’s suppose we increase the paper speed up to 50 mm/second. For this paper’s speed, we have to divide the above standard values of 25 mm/second over two to get the time duration of 50 mm/second. After dividing the values, the small box will count for 0.02 seconds. Whereas, the large box will be equal to 0.1 seconds. The formula to calculate the duration is:

Duration of measured distance = no. of boxes * duration of the box

Why is there a need for the ECG boxes to seconds calculator?

There are multiple small boxes in a big box of ECG. You have to manually calculate all boxes in a big box and then multiply their time factor according to the speed. The ECG boxes to seconds calculator is easy to use. You only need to add the overall number of boxes and the paper speed. It will provide you with the time duration of the ECG segments. You do not need to create messy calculations of small and big boxes of the ECG. Add the best values in the ECG calculator to get the accurate time duration of the selected segment.

How to use the ECG boxes to seconds calculator?

There is no such complexity regarding the use of ECG boxes to seconds calculator. This is the way to use this calculator.

  • Count the number of boxes either small or large. Smaller boxes are difficult to calculate. Choose the box type as large. And count the larger boxes and add the number of boxes.
  • Choose the paper speed of the ECG machine you set.
  • That’s it. You just need to put these values and this calculator will provide you with the duration of your desired segment in seconds or milliseconds.

What are the normal ECG values for different waves or segments?

Here are the normal ECG values to differentiate and diagnose the multiple diseases associated with ECG. Let us have a look at the normal values of ECG waves indicating the heart pattern duration.

  • P wave – 80 milliseconds
  • PR interval – 120 to 200 milliseconds
  • QRS complex – 80 to 100 milliseconds (some sources also mention the speed of QRS speed as 80 to 120 milliseconds)
  • ST segment – 80 to 120 milliseconds
  • ST interval – 320 milliseconds
  • T wave – 160 milliseconds
  • QT interval – it should be managed according to the patient’s heart rate.


The ECG boxes to seconds calculator provides an easy evaluation of the ECG boxes distance to the seconds. It is an easy tool to use and diagnose the multiple diseases associated with ECG patterns. There are multiple small boxes in every big box. Every box denotes a specific time duration. You have to manually calculate the number of boxes and multiply them by their time duration. But in the case of this calculator, you only need to put the number of boxes and paper speed. That’s it.

This calculator will provide you accurate duration of your selected segment. There is nothing to worry about the multiplication of boxes to times. Put the number only and get your desired results.

Frequently asked questions (FAQs)

What are the consequences if the time duration of the PR interval increases?

PR interval is increased in case of first-degree heart block. It indicates a disturbance in the electrical conduction system of the heart. In addition, it denotes a decreased speed for the conduction of electrical signals. In a typical first-degree heart block, the time duration of the PR interval increases up to 200 milliseconds.

What happens if the time duration of the ECG segment decreases?

The shortening of the time duration indicates an earlier depolarization of the action potential. In the case of the shortening of the PR interval, it indicates a typical exhibition of Wolf-Parkinson-White syndrome. In this condition, the time duration decreases to 120 milliseconds.

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