Is this a diagnostic guide?

No. This is educational reference for nurses learning to identify rhythms. Diagnosis is the clinician's responsibility.

What if the rate is borderline?

Outside 60–100 bpm with otherwise NSR-looking morphology means sinus brady or sinus tach — see those references.

How do I verify on the strip?

Walk calipers across 6+ R-R intervals to confirm regularity, and check lead II for upright P waves before every QRS.

Normal sinus rhythm — an educational nurse reference.

What normal sinus rhythm looks like on a strip, the intervals that confirm it, and what to verify with calipers.

Recognizing this rhythm at the bedside means matching pattern, intervals, and clinical context. This page covers the educational pattern; calipers and your clinical judgment carry it across the line.

What RN PocketPal does

Identifying traits

Rate: 60–100 bpm
Rhythm: regular
P wave: present, upright in lead II, before every QRS
PR interval: 0.12–0.20 sec
QRS: < 0.12 sec
QT: rate-dependent (use QTc)

Verify with

Calipers across at least 6 R-R intervals to confirm regularity.
Lead II for P-wave morphology.
Patient's clinical context (sinus tachycardia and bradycardia look like NSR with rate variation).

Who it’s for

For Nurses and nursing students learning rhythm interpretation.

Ten seconds of this rhythm, from a real recording

73 bpm · 10 seconds · each large grid square is 0.20 seconds. Amplitude is normalised for practice, so the vertical scale is not calibrated millivolts — read rate, regularity, and shape here, not voltage.

What to notice in this strip

Every QRS here is preceded by an upright P wave, and the R-R intervals march out evenly — walk calipers across three beats and the fourth lands where you predicted.

Counting the rate on a strip like this

The strip above is exactly ten seconds, so counting every QRS complex across it and multiplying by six gives the rate — the method that works whether the rhythm is regular or not. When the rhythm is regular, you can shortcut it: divide 300 by the number of large squares between two R waves.

Rhythms this gets confused with

Known-answer practice — RN PocketPal does not interpret your patient's monitor. To work through strips with the answer revealed after you commit, open Rhythm Practice.

Strip source: MIT-BIH Arrhythmia Database v1.0.0, record 100. Lead/channel 0, 10-second window, resampled to 100 Hz, zero-mean/unit-variance normalized for bundled practice use. Used under the Open Data Commons Attribution License v1.0. Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet. Circulation. 2000;101(23):e215-e220.

Frequently asked questions

Is this a diagnostic guide?: No. This is educational reference for nurses learning to identify rhythms. Diagnosis is the clinician's responsibility.
What if the rate is borderline?: Outside 60–100 bpm with otherwise NSR-looking morphology means sinus brady or sinus tach — see those references.
How do I verify on the strip?: Walk calipers across 6+ R-R intervals to confirm regularity, and check lead II for upright P waves before every QRS.

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Reviewed by RN PocketPal Clinical Team, RN. Last reviewed May 7, 2026.