# A blood pressure log your doctor can actually use

> A list of numbers gets skimmed. Six columns, a consistent time of day and a one-page summary get read. Here is what makes the difference.

Source: https://apps.swtlm.com/blog/blood-pressure-log-for-your-doctor · TLM Apps — focused mobile apps from a team of engineers.
Published: 2026-07-14 · Updated: 2026-07-14 · TLM Software Design

A useful log has six columns and fits on one page: date, time, systolic,
diastolic, pulse and a note. That is the whole difference between a record that
gets read during a ten-minute appointment and ninety unsorted rows that get
skimmed. The two columns people leave out are the time of day and the note, and
they are exactly the two that decide how everything else is read.

This is about record-keeping: what to write down and how to present it. It is
not medical guidance. How often to measure, at what times, and what any number
means for you are questions for the clinician who asked you to keep the log,
and their instructions override anything here.

## What goes in each row

**Date and time.** Blood pressure varies through the day in most people, so a
reading without a time is a number without a context. Two readings a week apart
at the same hour are more comparable than four readings on one day at random.

**Systolic and diastolic.** Both, always, written the way the device shows
them. Recording only the top number throws away half of the data.

**Pulse.** The monitor already shows it and it costs nothing to write down.

**Which arm.** Readings can differ meaningfully between arms. Pick one, use it
every time, and write down which one so nobody has to wonder.

**A note, when there is something to note.** "Straight after the stairs",
"slept badly", "new cuff". Three words. This is the column that turns an
alarming outlier into an explained one, and the reason never to delete a
reading you did not like.

## What makes a log get read

A log competes for attention with everything else in a short appointment. Three
things decide whether it wins.

**One page.** Not four screenshots. One page, in order, with the most recent
readings where they can be found.

**A summary at the top.** How many readings, over what period, and the average
and range of each number. That paragraph is what gets read first and sometimes
all that gets read.

**Consistency over volume.** Twenty readings taken at the same time each day
say something. Sixty taken whenever you remembered say much less, because the
variation between them is mostly the clock.

## The summary line, in detail

"A summary at the top" is the advice everyone gives and almost nobody makes
concrete. Here is what belongs in it, and why each part earns its space.

**How many readings, over what period.** Twenty-eight readings over four weeks
and twenty-eight readings over four days are different documents. The count
alone is meaningless; the count with its window is the first thing that tells
someone whether the rest is worth reading.

**An average for each number, separately.** Systolic and diastolic do not move
together, and averaging them into one figure destroys the only comparison worth
making.

**The minimum and maximum for each.** The average hides the thing an average is
worst at showing. Two logs can share a mean and describe completely different
months, and the range is what separates them in one glance.

**How you felt, counted.** If you have been noting whether a reading came on a
bad day, a normal one or a good one, the tally of those belongs in the summary
too. It is the only column that carries anything the monitor could not measure.

Some apps also print a classification band next to the average — normal,
elevated, one of the high stages — against the standard published ranges. That
is a convenience for reading the number, not a finding. It is arithmetic
applied to your own average, it knows nothing about you, and it is not a
diagnosis. [Ours](https://apps.swtlm.com/blood-pressure-diary) prints one and says exactly that next to it.

## Reminders, and the quiet cost of them

The most common failure of a home log is not a wrong entry. It is a missing
fortnight, because measuring at a fixed time is a habit nobody has yet. A daily
reminder fixes most of that, and it is worth knowing how one is built.

A reminder can be scheduled by the phone itself, or it can be sent from a
server. The first needs nothing but a time; the second needs a push token, a
device registered against your install, and a service that knows when to ping
it. For a reminder that says the same words every day at eight, the server
buys you nothing and costs you a permanent connection between a health app and
somebody's infrastructure.

If an app asks for notification permission, that alone tells you nothing.
What tells you something is whether the app also needs an account, or works
without ever reaching a network. [Ours](https://apps.swtlm.com/blood-pressure-diary) schedules its reminders locally and has no
messaging service behind it at all — the same reason it needs no account, which
[where your health app data goes](https://apps.swtlm.com/blog/where-your-health-app-data-goes)
unpacks.

## Paper or an app

Both work. They fail differently, which is the useful way to choose.

**Paper** cannot be lost to a phone upgrade, needs no battery, and is already
in the format the appointment uses. It is easy to skip a row, easy to misread
your own handwriting six weeks later, and the summary has to be worked out by
hand.

**An app** takes seconds per entry, cannot be misread, keeps the time stamp
without being asked, and can produce the one-page summary automatically. It is
lost if you lose the phone and have no export, which is the failure worth
designing against: **whichever app you use, export it once, early, and confirm
the export actually opens.** An app you cannot get data out of is a diary you
are renting.

## Where the readings go

Health readings are the most sensitive thing most people put into a phone, and
what happens to them varies enormously between apps that look identical. The
short version: a tracker does not need a server to do this job, since the
arithmetic is trivial and the data is tiny. An app that requires an account has
made a choice rather than met a constraint.
[Where your health app data goes](https://apps.swtlm.com/blog/where-your-health-app-data-goes) covers
what to check, and where the stores make each app declare it.

## What we built

[Blood Pressure Diary](https://apps.swtlm.com/blood-pressure-diary) is the version of the above we
wanted to exist. A reading is one screen — the two numbers, the pulse, how you
felt, an optional note — with the date and time filled in for you. The monthly
view gives the summary described above without being asked. And it produces the
one-page PDF, summary at the top and readings in order, which is the artefact
an appointment actually uses.

It works fully offline, has no sign-in and no cloud sync, so the readings sit
on the device and nowhere else. Reminders are scheduled by the phone; there is
no messaging service involved. There are no ads, and there is no subscription.

Since honesty about our own monetization is the point of writing any of this:
logging, the journal, the graphs and the reminders are free permanently. The
PDF report and CSV import/export are free for the first two months, and after
that a single **$1.99** purchase unlocks them for good and removes the periodic
offer banner. Nothing about the core diary is ever locked, and nothing renews. The reasoning
behind one-time rather than monthly is the same everywhere we apply it —
[what a puzzle game subscription costs](https://apps.swtlm.com/blog/what-a-puzzle-game-subscription-costs)
sets out the three models and how to tell them apart on a listing.

The interface is deliberately large-print and plain, because the people most
often asked to keep one of these are not the people best served by a dense
dashboard. Why we build that way rather than the other way is on the
[About page](https://apps.swtlm.com/about).

The rest of what we make for tracking and sleep is on the
[Health & Sleep page](https://apps.swtlm.com/health).

## Frequently asked questions

**What should a blood pressure log include?**

Date, time, systolic, diastolic and pulse, plus which arm and anything unusual about that reading. Time of day is the column people leave out and the one that changes how the rest is read.

**How many readings should I bring?**

Ask the clinician who asked you to keep it — the number and the schedule are part of the instruction, and they vary by why you are measuring. What is universal is that readings taken at a consistent time are worth more than more readings taken at random.

**Is an app better than paper?**

Only in the ways that matter to you. Paper cannot be lost to a phone upgrade and needs no battery. An app is faster to enter, cannot be misread, and can produce a printed summary — which is the format a consultation actually uses.

**What makes a log get ignored?**

Length without structure. Ninety unsorted rows across four screenshots is not something anyone can read in a ten-minute appointment. One page with an average and a range gets read.

**Should I leave out the bad readings?**

No. A log with the unusual readings removed is a log that cannot answer the question it was kept for. If a reading was taken in unusual circumstances, note the circumstance next to it rather than deleting the row.