The ECG paper speed is ordinarily 25 mm/sec. As a result, **each 1 mm (small) horizontal box corresponds to 0.04 sec (40 ms)**, with heavier lines forming larger boxes that include five small boxes and hence represent 0.20 sec (200 ms) intervals.

## How many seconds is a normal ECG?

Normally **between 0.12 and 0.20 seconds**.

## What is 10 seconds on an ECG?

If the heart rate is irregular, count the number of QRS complexes on the ECG and multiply by 6 to obtain the average heart rate in bpm (the ECG displays a period of 10 seconds; thus, 6 × 10 seconds = **60 seconds** [1 minute]).

## How many boxes are in a 6 second strip?

The second method can be used with an irregular rhythm to estimate the rate. **Count the number of R waves in a 6 second strip and multiply by 10**. For example, if there are 7 R waves in a 6 second strip, the heart rate is 70 (7×10=70).

## How many seconds is each small block?

Each small block equals **0.1 mV**. Within the large blocks are 5 small blocks, each representing 0.04 seconds.

## How do you calculate ECG blocks?

Youtube quote:*So 30 large squares equals six seconds because five small squares equals zero point two zero seconds. So when you add up all these large squares thirty of them you get your six seconds.*

## What is the second method of determining the heart rate?

Youtube quote:*The number of squares between each QRS complex and multiplying by 40 milliseconds. Gives you the cycle length of a patient's heart rate. You then divide 60,000.*

## How do you calculate heart rate on ECG small box?

When the rhythm is regular, the heart rate is 300 divided by the number of large squares between the QRS complexes. Because there are 5 small boxes in one large box, an alternative, more tedious way is to **count the number of small boxes for a typical R-R interval and divide 1500 by this number** to determine heart rate.