BP LogMorning blood pressure surge calculator
Enter morning and evening home readings to see the morning-minus-evening difference in the top number, the home measure researchers use for morning surge.
Morning minus evening
Enter home readings taken after waking (before medicine and coffee) and before bed, ideally over a week. One reading per line, like 132/84.
0 found
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Enter at least one morning and one evening reading.
What morning surge means
Researchers use “morning surge” for the rise in blood pressure around waking. With a 24-hour monitor it can be measured directly; with a home cuff, the practical version is the difference between your morning and evening readings. Heart attacks and strokes are more common in the morning hours, which is why the morning rise has been studied for decades.
Our guide to morning vs evening blood pressure covers what the research shows and how to take both readings.
How it is calculated
The tool averages the top number of every morning reading and every evening reading, then subtracts the evening average from the morning average. A positive difference means mornings run higher. The calculation comes from the shared code library behind the BP Log apps.
Common questions
Is blood pressure normally higher in the morning?
Often, yes. Blood pressure rises as you wake up, and in many home-monitoring studies morning readings come out higher than evening ones. A small morning-evening difference is common.
How big a difference matters?
There is no cutoff in the 2025 ACC/AHA guideline. In the Japanese J-HOP study, a morning-minus-evening difference in the top number of 20 mmHg or more was linked to higher cardiovascular risk, independent of the average. It is worth showing your doctor a consistently large gap.
Should I take my blood pressure medicine at night instead?
Do not change when you take medicine without talking to your doctor. In the large TIME trial, taking usual blood pressure medicine in the evening instead of the morning made no difference to heart attacks, strokes or deaths.
- Difference between morning and evening home blood pressure and cardiovascular events: the J-HOP Study (Hypertension Research, 2021): In 4,258 Japanese adults, a morning-minus-evening systolic difference of 20 mmHg or more was linked to higher cardiovascular risk independent of average home blood pressure
- Morning blood pressure surge: pathophysiology, clinical relevance and therapeutic aspects (Integrated Blood Pressure Control, 2018): Review of morning surge definitions and evidence; no outcome trials of lowering the surge itself
- Muntner P, et al. Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association (Hypertension, 2019): How to measure; home protocol of 2 readings a minute apart, morning and evening, for 7 days; cuff sizes by arm circumference; white coat and masked hypertension definitions; home 130/80 corresponds to office 130/80
The free iPhone app times two readings a minute apart, averages them, keeps your morning and evening numbers apart, and builds a report for your doctor.
Other ways to track: desktop, Excel and printable logs