Longevity · Explainer
How to Measure Your Blood Pressure Properly
The most predictive number in medicine, the cheapest to measure, and the one most people get wrong at home in the same four ways.
By Julien Malet, · Updated 2026-09-09
If you do one thing from this site, do this. Elevated blood pressure is a leading modifiable risk factor for cardiovascular disease and stroke, it produces no symptoms until it produces a serious event, and a cuff costs about $40.
Home measurement is also more informative than the reading taken in a clinic — provided you do it correctly, and most people do not.
Buy the right device
An upper-arm cuff, validated, automatic. Not a wrist monitor and not a finger device — both are meaningfully less accurate.
Check the cuff size. This is the most common purchasing error. A cuff too small for your arm reads falsely high, sometimes by a lot. Measure your upper-arm circumference and buy accordingly; if you are between sizes or muscular, buy the larger.
Look for validation. Independent lists of validated devices exist (validatebp.org in the US, among others). Plenty of cheap monitors have never been validated against a reference standard.
Expect to spend $35–60. Above that you are buying app connectivity, not accuracy.
The measurement protocol
The four things people get wrong are all in here.
- No caffeine, exercise or smoking for 30 minutes beforehand.
- Empty your bladder. A full bladder raises readings measurably.
- Sit for five minutes doing nothing first. This is the step everyone skips and it is worth several points.
- Sit properly: back supported, feet flat on the floor, legs uncrossed.
- Bare arm, cuff on skin, not over a sleeve.
- Arm supported at heart height — resting on a table, not held up and not hanging down. An unsupported arm adds several points.
- Do not talk. Talking during measurement raises readings.
- Take two or three readings, one minute apart, and record the average — not the lowest, which is the tempting error.
Measure at the same times on measuring days. Morning before medication and coffee, and evening, is the usual pattern.
What the numbers mean
Using the current American College of Cardiology / American Heart Association categories:
| Category | Systolic | | Diastolic | | --- | --- | --- | --- | | Normal | under 120 | and | under 80 | | Elevated | 120–129 | and | under 80 | | Stage 1 hypertension | 130–139 | or | 80–89 | | Stage 2 hypertension | 140 or higher | or | 90 or higher | | Hypertensive crisis | over 180 | and/or | over 120 |
Home readings tend to run slightly lower than clinic readings, and thresholds for home monitoring are usually set a few points below the clinic ones. Your doctor interprets against the right threshold — bring your log rather than a single number.
Two patterns only home measurement finds
White-coat hypertension — high in the clinic, normal at home. Common, and it can lead to unnecessary treatment.
Masked hypertension — normal in the clinic, high at home. This is the dangerous one, because it is untreated hypertension that looks fine at every appointment. It is associated with cardiovascular risk similar to sustained hypertension, and a clinic visit will never find it.
That second pattern is the strongest argument for owning a cuff.
What moves it
- Aerobic exercise. Among the most effective non-drug interventions.
- Weight loss, if applicable. Roughly 1 mmHg per kilogram in many people.
- Sodium reduction, meaningful particularly in salt-sensitive individuals.
- Alcohol reduction. Direct and reasonably fast.
- Potassium intake from fruit and vegetables. Note the interaction caution if you take an ACE inhibitor, ARB or spironolactone.
- Sleep. Poor and short sleep raise it.
- Medication, which is cheap, well studied and effective. Not a failure.
Beetroot and nitrate-containing supplements produce small, real reductions — a few mmHg in some trials. Worth knowing, and not a substitute for the interventions above or for treatment.
Track it alongside the other biomarkers worth measuring, and take the log to your next appointment.