A diary, not a diagnosis. Built by software people, not clinicians.

Tonelva is a blood pressure diary for iPhone and Android, made by a small independent software team. We are not doctors, nurses, pharmacists or a medical organisation, and we do not present ourselves as any of those. That is the first thing you should know, because in health content the authority of the author changes how much weight a page deserves.

What we are is careful. Everything published here is built from the published guidelines of the American College of Cardiology and American Heart Association and of the European Society of Cardiology and European Society of Hypertension, and from the measurement protocols those bodies describe. Where a question is clinical, we say so and point at the person who should answer it rather than paraphrasing them badly.

Why the site exists

It started with a contradiction we could not resolve while building the app. A reading of 135/85 is stage 1 hypertension according to one perfectly reputable source and high-normal blood pressure according to another, equally reputable. Both are correct within their own framework. Almost nothing on the web explains that, because most pages are written for one country and quietly assume its guideline is the guideline.

For somebody anxious about their numbers, that is genuinely distressing: they read two trustworthy pages, get two different answers, and conclude that nobody knows. So we made a rule. Every category shown in the app and on this site appears under both frameworks, side by side, with a plain explanation of why they differ. It is the single most useful thing here and it is why the site exists at all.

What we will not do

We do not diagnose. We do not set targets — yours is individual and belongs to your clinician. We never suggest starting, stopping or changing a medication, and we do not publish anything that reads as a plan to follow instead of speaking to your doctor.

We also refuse the tone that dominates this category. Health content aimed at people over fifty is frequently either alarming or condescending, and both are bad for the reader in a specific and measurable way here: anxiety raises blood pressure, so a page that frightens somebody about their number can change the next number they record. We write calmly on purpose. Accuracy delivered without drama is the whole editorial job.

The thing we say most often, and mean

No phone can measure blood pressure. Not a camera, not a fingertip on the screen, not an app that asks you to hold still. Blood pressure measurement requires occluding an artery and detecting the pressure at which flow returns, and a phone has no way to do it. Apps claiming otherwise are measuring something else, or nothing at all.

We repeat it because the app stores are full of them, and because somebody who trusts a fingertip reading instead of buying a validated cuff may never find out their real numbers. If a single paragraph on this site is worth quoting elsewhere, we would like it to be that one.

How we make money, stated plainly

Logging readings and keeping unlimited history are free in the app. A Pro subscription adds the PDF report, medication reminders, longer trend windows and export. That is the entire business model.

This website carries no advertising and no affiliate links. We take no commission on cuffs, monitors or anything else, and we accept no sponsorship from device manufacturers, pharmacies or clinics. That matters in this category more than in most: the moment a page here earned money from a cuff recommendation, every other claim on the site would deserve more scepticism. So we do not make any.

How the app is built

There is no server, no account and no cloud sync. Readings live on your device, the categories are derived rather than stored so switching between the two scales re-renders your whole history instantly, and the PDF is generated on the phone. The App Store label reads Data Not Collected because that is literally true.

The trade-off is real and we would rather name it than sell it as a feature: no backup from us, no sync between devices, and no way for us to recover a lost history. In a category where several free apps monetise health data, we think holding none of it is the right call, and Apple Health sync gives you a recovery path that does not involve us at all.

Two design choices are worth explaining because they came from watching real use. The entry screen takes three taps, because the twenty-eighth reading of a monitoring week is the one people skip and every second of friction costs completions. And morning and evening are averaged separately rather than merged, because blood pressure rises on waking and a single daily number destroys the pattern a clinician actually wants to see.

On being non-clinicians writing about health

There is a fair objection to a software team publishing health reference material, and we would rather address it than hope nobody raises it. Our answer is about scope. We write about what the published guidelines say, how a measurement protocol works, and where two standards differ — questions with documented answers that can be checked against a source. We do not write about what any of it means for you, because that requires clinical judgement we do not have.

That line is why you will find a long explanation of why a cuff that is too small reads high, and no explanation at all of whether your reading warrants treatment. The first is physics and documented practice. The second is medicine. Keeping the two apart is the main thing that makes a site like this defensible, and where we have drifted across the line we would like to be told.

Editorial rules

We do not invent numbers. Where a claim would need a study we do not have, we describe the direction of the evidence and name the guideline body rather than manufacturing a percentage or a risk figure.

We show both frameworks every time, including where doing so makes an answer less tidy. A reader deserves to know that the label depends on which side of the Atlantic the page was written on.

Our comparison pages name situations in which a competitor is the better choice, and mean them. Facts about other apps come from public store listing data on a stated date and from the developers' own descriptions; we do not speculate about features we cannot verify and we do not repeat review complaints as though they were established.

We correct errors visibly, and guidelines change, so pages here can fall behind. If you find something wrong or out of date — particularly if you work in this field — write to [email protected]. We fix it and note that we have, rather than editing quietly.

Who this is for

Somebody who has just been given a cuff and told to keep a record for a fortnight. Somebody managing hypertension long-term who wants their own numbers rather than only the ones taken in a clinic, where the white coat effect is real. And somebody keeping a record for a parent or a partner, which happens more often than the app stores seem to assume.

There is a reader we are not trying to serve, and saying so saves time: if you want an app that measures your blood pressure without a cuff, coaches you, or connects to a wellness programme, this is the wrong one. The first of those is not possible, and the other two are not what we built.

What we are working on

Bluetooth cuff pairing is the most requested feature and the one we are most cautious about. Every manufacturer implements it differently, a half-working integration is worse than typing three numbers, and the manufacturers' own apps already do it. If we ship it, it will be because we can support a small number of devices properly rather than claiming broad compatibility we cannot honour.

Wider language coverage matters more than it looks. This is a condition managed by people in their sixties and seventies, and reading a health app in a second language is a real barrier — one that mostly affects exactly the markets where the alternatives are weakest. Beyond that, the improvements we care about are unglamorous: better handling of an interrupted monitoring week, clearer prompts when a reading looks like it was taken without a rest period, and a report layout that survives being printed in black and white on a busy practice printer.

Why the section is called Vitals

A small naming decision that reflects an editorial one. A blog implies opinion, frequency and personality; what that section actually contains is reference material — pages meant to be returned to, checked against and quoted rather than read once. The test for publishing something is not whether the topic would attract traffic, but whether we can say something true and specific that the pages currently ranking do not. In this subject that gap is usually the same one: they show a single guideline and never mention that another exists.

Where to start

If you have a reading in front of you, the category checker shows it on both scales in a second. If you have been asked to monitor at home, read the seven-day protocol first — it is short, and doing it properly is worth more than any number of casual readings. If you are preparing for an appointment, the average calculator produces the figure a clinician actually wants. And if you have ever been confused by two websites giving you different answers, start with why the American and European guidelines disagree.