Why 3 days, not a single reading?
A single blood pressure reading, especially one taken at a doctor's office, is affected by the stress of the visit ("white coat effect") and by the natural variability of blood pressure throughout the day. Health authorities recommend the "rule of 3": 3 consecutive days, 3 readings in the morning and 3 in the evening, to get an average over 18 readings that is far more reliable than a single measurement.
One protocol everywhere, a threshold that differs by country
Unlike other tools on this site, the measurement and the home blood pressure monitoring protocol are identical worldwide. Only the threshold used to interpret the average changes depending on the guidelines in force in your country:
- France / Europe (HAS, SFHTA, ESC 2024): hypertension from a home-monitoring average of 135/85 mmHg.
- United States (AHA/ACC 2017, confirmed by the 2025 update): a lower threshold, with an intermediate "stage 1" tier starting at 130/80 mmHg, then "stage 2" from 140/90 mmHg.
- Rest of the world (WHO/HEARTS): a clinical threshold of 140/90 mmHg, which corresponds to the equivalent of the European threshold once translated to home monitoring — this tool therefore applies the same interpretation grid as the France/Europe branch for this region.
In practice, the same average of 133/82 mmHg can be classified as "normal" in France and "stage 1 hypertension" in the United States: this is not an error, just two different diagnostic thresholds. Comparing a result from here with one read elsewhere only makes sense if you selected the same reference country.
An emergency to know about, regardless of your region
Above an average of 180/110 mmHg, this is no longer a routine screening result to discuss at a future appointment: it is a potential hypertensive emergency, which warrants prompt medical attention, whichever branch you selected.
Your readings stay on your device
Like every tool on this site, no reading is ever sent to a server. One nuance is worth spelling out clearly: unlike the other tests on this site (calculated once, nothing kept afterward), this one needs to remember your entries from one day to the next so you can resume the protocol without re-entering everything. This data stays stored locally in your browser, only on this device, never transmitted nor accessible to anyone else — you can erase it at any time with the button provided for that purpose.
The link with cardiovascular risk
High blood pressure is one of the main modifiable cardiovascular risk factors. If this log confirms elevated blood pressure, our "What is my cardiovascular risk?" tool lets you estimate your overall 10-year risk.
