How to Average Home Blood Pressure Readings: Step-by-Step Protocol
Single blood pressure readings vary from minute to minute. Learn how clinical guidelines structure 4-to-7-day home blood pressure monitoring and how to average systolic and diastolic readings accurately.
Standard Seated Preparation Before Every Reading
Before pressing start on an upper-arm oscillometric blood pressure monitor, avoid caffeine, exercise, and smoking for at least 30 minutes, and empty your bladder.
Sit quietly in a chair with back support for at least 5 minutes. Keep both feet flat on the floor (legs uncrossed) and rest your bare or thinly sleeved upper arm on a table so the middle of the cuff sits at heart level.
How the 7-Day Home Monitoring Schedule Works
Both the UK NICE NG136 guideline and AHA/ACC scientific statements recommend taking at least two consecutive readings, 1 minute apart, each morning (before medications and breakfast) and each evening (before dinner or bedtime) for 4 to 7 days.
Under NICE NG136, all readings taken on Day 1 are discarded because first-day readings frequently reflect an initial alerting response. The remaining morning and evening readings from Days 2 through 7 are averaged separately for systolic and diastolic pressure.
| Protocol Step | Simple Average Mode | NICE NG136 Protocol Mode |
|---|---|---|
| Readings per session | 1–2 seated readings | 2 seated readings, >=1 min apart, AM & PM |
| Duration | Any multi-reading log | 4 to 7 consecutive days (7 days preferred) |
| Day 1 handling | Included in mean | Excluded from mean |
| Calculation | Arithmetic mean of all SBP and all DBP | Arithmetic mean of Days 2–7 SBP and DBP |
Limitations and When to Seek Medical Care
- If a home reading exceeds 180/120 mmHg, wait 5 minutes and retest; if still >180/120 mmHg or accompanied by chest pain, shortness of breath, numbness, weakness, vision changes, or difficulty speaking, seek emergency medical care immediately.
- Do not start, stop, or change blood pressure medication doses without consulting your prescribing clinician.
Related Calculators
Home Blood Pressure Average Calculator
Calculate your average systolic blood pressure, diastolic blood pressure, and pulse across multiple home readings. Choose between averaging all entered rows or applying the NICE NG136 home monitoring protocol (which discards Day 1 readings).
Blood Pressure Calculator (Category, Pulse Pressure & MAP)
Classify an adult blood pressure reading against the 2017 ACC/AHA adult reference table and calculate Pulse Pressure (PP) and estimated Mean Arterial Pressure (MAP) in mmHg.
Printable Blood Sugar & Blood Pressure Log Sheet
Create a clean, clinic-ready weekly or monthly paper log sheet for blood glucose (mg/dL or mmol/L) and blood pressure (mmHg + pulse) — either as a blank printable template for your refrigerator/clipboard or pre-filled with readings.
Frequently Asked Questions
Do I average systolic and diastolic together or separately?
Always average all included systolic numbers together to get the mean systolic, and average all included diastolic numbers together to get the mean diastolic.
Sources and Review Information
- [S12] National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management (NG136). Confirming diagnosis with home blood pressure monitoring. Reference Source
- [AHA-2017] Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA High Blood Pressure Clinical Practice Guideline. Hypertension. 2018;71(6):e13-e115. Reference Source
Prepared by: GlucoBP Editorial & Engineering Team · Verification status: Formula verified against published reference; clinical review pending · Last updated: 2026-11-15