Blood pressure average

1

What does the Blood pressure page show?

One average of your recent cuff readings, with a word for it. Under it, a sentence says which number put you there.

Open the page and the top shows one figure, your top number over your bottom number, with a word beside it. Under it, one sentence says which of your numbers put you in that word. Below sits a map where each dot is one day's readings averaged. Then comes a This week section with a row of marks for Mornings and one for Evenings, each ending on its own average.

The word is one of four. In range means both numbers are under 120 and 80. A little high is a top number in the 120s with the bottom still under 80.

High is a top number from 130 to 134, or a bottom number from 80 to 84. Very high is 135 or more on top, or 85 or more on the bottom. The higher word wins when your two numbers disagree.

History holds every reading Aera can read, up to a year back. Pick Week, Month, 3 months or Year and it shows the average, the lowest and the highest, which go by the top number. A log by day gives each session its own column.

2

What goes into it?

Readings that your cuff saved to Apple Health. Aera reads them from there when it needs them and keeps no copy.

Any cuff whose app saves to Apple Health fills the page. Aera's own screen names Omron, Withings and iHealth as examples. Aera reads up to a year of readings from Apple Health when a screen needs them and keeps no copy, so Apple Health stays the record.

Readings typed into Apple Health by hand count too, and the log labels an untagged one Typed. Readings that no upper-arm cuff could make are dropped as typing slips, such as a top number over 260 or a bottom number over 160. Aera's empty page says Apple Watch's high blood pressure notifications do not save readings, so they do not show here. Why a watch estimate is only a hint is told in Blood pressure.

Each reading also gets a time of day. From early morning to noon it is a morning reading, from noon to five it is midday, and anything later, into the small hours, is evening. Aera's code takes its two sessions, morning and evening, from the European home protocol. Midday readings count in every total but never in the morning or evening averages, and they get their own row only once they are a habit, on 3 days of the week.¹

3

How is the average worked out?

From your newest week of readings, as long as it is recent. Days without a reading are skipped, not counted as zero.

The big figure is the average of every reading in your newest 7 days with readings, taken from the last 14 days. A day with no reading is skipped, not counted as zero. A day with several readings counts several times, because the average runs over readings, not days. The top and bottom numbers are averaged apart and rounded half up.

The map works differently. Each dot is one day's readings averaged, and your latest sitting, the readings of one session on one day, is drawn as one dot of its own, with a tag such as This morning. So a quick re-check shows as one dot on the map, while in the average every reading counts.

Why average at all? A team in Durham measured blood pressure again and again in 444 veterans with high blood pressure, over 18 months, in the clinic, in a research setting and at home. A person's readings varied by about 10% around their own average, about as much at home as in the clinic.²

No single clinic reading in a wide middle stretch could settle, with 80% certainty, whether pressure was under control. Averaging several readings greatly cut the noise, and most of the gain came by 5 to 6 readings. The patients were mostly men with long-standing high blood pressure, chosen for poor control, so your spread may differ.²

Aera's early-read line draws on this. Under 5 readings, the page calls the figure an early read and says how many readings are behind it. The word itself needs readings on at least 3 days. Aera's code takes the 7 days and the 3-day floor from the European home-measurement protocol.¹

4

How does the average get its word?

The higher of your two numbers decides the band. A sentence under the word says which number did it.

Each reading, and the average, takes the highest band either number reaches. So a bottom number of 80 or more lifts you out of In range even when the top number is fine. These are home lines. Aera's code takes the 135 over 85 line from the 2021 European guideline on home measurement, and the lower lines from an American table of home equivalents.¹

The sentence under the word names the number that put you there, in the app's words: your top number was in the 120s, or your bottom number was in the low 80s. It says "mostly" when over half your readings sit in that band, and "on average" when only their average does.

Then it sets your mornings beside your evenings. If their top numbers are less than 5 points apart, it says they are alike. A gap of 5 or more reads as mornings, or evenings, running higher. With fewer than 5 readings it skips this and says the figure is an early read.

The 5 points is Aera's choice: its code sets it at the most a validated cuff may be off on average, and treats a smaller gap as not a real one. Experts from the American, European and international standards bodies agreed the basis of one shared standard for checking such devices.³

5

What happens with a very high reading?

A very high reading from the last couple of hours opens a sheet that tells you to rest and measure again.

If a reading in the last 2 hours is above 180 on top or above 120 on the bottom, the page opens a sheet. It says "That's very high." and tells you to sit quietly and measure again in a minute or two. It says to call emergency services now if you also have chest or back pain, shortness of breath, numbness or weakness, or trouble seeing or speaking. Without any of these, it says to measure again and let your doctor know today.

Aera's code takes this line from the 2025 American guideline. The sheet is separate from the four words: one reading over the line opens it, even when your average is In range.⁴

6

When does it show nothing?

Until your readings cover enough days, and again once they go stale. Aera does not guess.

With no readings at all, the page says "No readings yet" and "Needs a cuff". With readings on fewer than 3 days, it says "Still learning" and counts down the days left for a fair average. The map shows the readings so far.

The figure is current only while your newest reading is under 14 days old. After that the page says "Nothing new" and gives the date of your last reading, with no figure and no colour, so an old check never reads as today. That check stays on the map and in History.

If you turn on the Reminder, Aera sends one note at nine in the morning, once a week has passed since the day of your last reading. A new reading takes that note back.

7

What can't it tell you?

Whether you have high blood pressure. It reads what your cuff saved, and it is not a medical device.

Tap a reading to say what was going on, such as coffee or a short night. Tags stay on this iPhone unless you export a report, and they never change the figure or the word.

The average is only as good as how you measured. Aera sees the numbers your cuff saved, not how you sat or whether you rested first. How to measure, and why arm position moves the numbers, is told in Blood pressure.

Your week also feeds Body age, which looks back further than this page: once the last 30 days hold readings on 3 days or more. The newest 7 days of readings count, and a week counts fully from 12 readings.

Only a doctor can say whether you have high blood pressure or need treatment. If a reading worries you, or you have symptoms, talk to a doctor.