How to Take Blood Pressure Manually
By the BP Monitor Lab editorial team · Written from manufacturer documentation and published guidance, not from our own device testing · Last checked: August 28, 2026
Manual measurement is the method every automatic monitor is judged against, and it is also the method most likely to be done badly. Both of those things are true at once, and the reason is the same: the accuracy lives in the operator.
What this page is. An explanation of how the auscultatory method works and where it goes wrong, written for people who want to understand it. It is not a training course, and reading it will not make you competent to measure blood pressure for clinical decisions. If you are monitoring your own blood pressure at home, the right tool is a validated automatic monitor, not a stethoscope.
What the Auscultatory Method Actually Is
A cuff is inflated around the upper arm until it squeezes the brachial artery shut and blood stops flowing through it. The pressure is then let down slowly. As soon as the cuff pressure drops just below the peak pressure in the artery, blood starts jetting through the narrowed vessel in bursts, and those bursts make a sound you can hear with a stethoscope placed over the artery.
The pressure on the gauge when those sounds first appear is the systolic reading. Keep letting the pressure down and the artery stays open for more of each heartbeat, until eventually it never fully closes and the sound stops. The pressure when the sound disappears is the diastolic reading. That is the whole idea. Everything else is care.
Korotkoff Sounds, in Five Phases
The sounds are named after Nikolai Korotkoff, who described them in 1905, and they are conventionally split into five phases. Only two of them are recorded.
| Phase | What you hear | What it marks |
|---|---|---|
| I | The first clear tapping sounds appear | Systolic pressure |
| II | A softer, swishing quality | Nothing recorded |
| III | Crisper and louder tapping returns | Nothing recorded |
| IV | The sound suddenly becomes muffled | Diastolic in some children and in pregnancy, when phase V is unclear |
| V | Sound disappears completely | Diastolic pressure in adults |
Phases II and III exist to be listened through, not written down. The trap in them is the auscultatory gap, described below.
The Equipment
- • A sphygmomanometer. The cuff plus a pressure gauge. Mercury columns were the old standard and have largely been retired on environmental grounds, so aneroid dial gauges are what most people meet now.
- • A stethoscope. The bell or the diaphragm sits over the brachial artery, below the lower edge of the cuff and not underneath it.
- • A cuff that fits. The sizing rules are identical to the automatic case, and a cuff that is too small reads high whether a machine or a person is reading it. See cuff sizing.
- • A calibration check. Aneroid gauges drift. They need checking periodically against a known reference, which is a maintenance burden an automatic monitor does not put on you in the same way.
How It Is Done
The preparation is the same as for any reading: five minutes seated and quiet, back supported, feet flat, arm bare and supported at heart height. Our technique guide covers that part in full, and none of it becomes optional because a person is holding the gauge.
- 1. Find the pulse first. Feel the radial pulse at the wrist, inflate until it disappears, and note that pressure. This is the palpated estimate.
- 2. Inflate 20 to 30 mmHg above that. Guessing high enough matters, because starting below the true systolic is how the top number gets missed entirely.
- 3. Place the stethoscope over the brachial artery, in the crook of the elbow, below the cuff rather than tucked under it.
- 4. Deflate at 2 to 3 mmHg per second. Slower than feels natural. This single number is responsible for a large share of manual measurement error.
- 5. Record phase I and phase V to the nearest 2 mmHg, without rounding to the nearest five or ten.
- 6. Let the arm rest before repeating. Back-to-back inflations congest the arm and change the next reading.
Where Manual Measurement Goes Wrong
These are the errors that belong to the method rather than to the patient, and they are the reason the AHA's measurement statement spends so long on technique.
- • Deflating too fast. At 5 or 10 mmHg per second the gauge sails past the true points between beats.
- • Terminal digit preference. People round to a zero or a five without noticing. It is visible in any large set of hand-recorded readings and it is a genuine bias, not a rounding nicety.
- • The auscultatory gap. In some people the sounds vanish for a stretch after phase I and return later. Someone who starts listening inside that gap records a systolic far too low. Palpating first is what prevents it.
- • Hearing. The sounds are quiet. Ordinary age-related hearing loss makes phase V genuinely hard to place, and no amount of care compensates for not hearing it.
- • Expectation. Knowing what the last reading was, or what you hope it is, moves what people record. Automatic devices are indifferent in a way humans are not.
- • An uncalibrated gauge. Aneroid dials drift quietly and nothing on the device tells you.
Why Validation Studies Still Use It
If manual measurement is this error-prone, it is fair to ask why it is the reference. The answer is that the errors above are operator errors, not method errors, and a validation study controls for them: trained observers, calibrated equipment, two people reading independently, and a protocol that discards disagreements. Under those conditions the auscultatory method is the closest practical stand-in for the pressure inside the artery. That is what an automatic monitor is measured against when it is tested to ISO 81060-2, which asks for a mean difference within 5 mmHg and a standard deviation of no more than 8 mmHg. None of those controls exist on a kitchen table.
So Should You Learn It?
If you are monitoring your own blood pressure, no. A validated automatic monitor removes the hearing, the timing and the reading judgement in one go, and the guidance that asks for home measurement assumes exactly that kind of device. Buying a stethoscope to check your own blood pressure adds three new ways to be wrong and removes none.
It is worth learning if you are being taught it as part of clinical training, if a clinician has specifically asked you to use one, or simply because you want to understand what the machine on your table is imitating. That last reason is a good one, and it is most of why this page exists. For a side-by-side of the two approaches, see manual versus digital monitors.
Frequently Asked Questions
How do you take blood pressure manually?
You inflate a cuff above the point where the brachial pulse disappears, then let the pressure down slowly while listening over the artery with a stethoscope. The pressure at which tapping sounds first appear is the systolic reading. The pressure at which they disappear is the diastolic reading. This is called the auscultatory method, and doing it accurately takes training and practice.
What are Korotkoff sounds?
They are the sounds heard through a stethoscope over the brachial artery as a blood pressure cuff deflates, named after Nikolai Korotkoff. They are described in five phases. Phase I is the first appearance of clear tapping, which marks systolic pressure. Phase V is the point where the sounds disappear, which marks diastolic pressure in adults.
Is manual blood pressure more accurate than an automatic monitor?
In trained hands under good conditions it is the reference method, which is why validation studies compare automatic monitors against it. In untrained hands it is usually worse than a validated automatic cuff, because it adds hearing, timing and reading judgements that the machine does not make. Accuracy here belongs to the operator at least as much as to the equipment.
How fast should you deflate the cuff?
Slowly, at roughly 2 to 3 mmHg per second. Letting the pressure down faster is one of the most common sources of error, because the needle passes the true systolic and diastolic points between heartbeats and the reading lands low or high by several mmHg.
What equipment do you need to take blood pressure manually?
A sphygmomanometer, which is the cuff with a pressure gauge, and a stethoscope. Aneroid gauges are the common type now that mercury devices have largely been retired for environmental reasons. Aneroid gauges drift over time and need periodic calibration checks against a known reference.
Should I buy a manual blood pressure kit for home use?
For almost everybody monitoring their own blood pressure at home, no. A validated automatic upper arm monitor gives more reliable numbers with far less that can go wrong, and it removes the hearing and timing judgements that make manual measurement hard. Manual kits make sense if you are being trained to use one, or a clinician has asked you to.
Why do some readings end in a zero?
That is terminal digit preference, and it is a well-documented bias in manual measurement. People unconsciously round to the nearest zero or five when reading a dial, which clusters recorded readings on round numbers. It is one of the reasons automatic devices are preferred in research and increasingly in clinics.