Calu’s rules
How Calu works.
And how well.
Calu helps with four questions: which specialty fits, whether you need a referral, who pays and what to bring. Here are its rules, with figures.
What Calu is
An assistant with fixed rules.
Calu shows you which specialty fits. You decide.
In the app
Calu runs on your iPhone.
We never save what you write to Calu.
Here on the website
Calu knows the most common questions and answers on the home page.
We never save what you write here.
Fixed answers where money is involved
In the app, Calu answers questions about referrals, insurance and costs with texts our team wrote.
What your insurer says is binding.
Ground rules
What always holds for Calu.
In the app and on this website, under Calenu’s intended purpose.
Your practice makes the diagnosis
Your doctor tells you what you have. Calu shows you the way there.
Unsure? Call.
112 in an emergency, otherwise 116117. Calu does not judge how urgent something is.
No “wait and see”
Calu never tells anyone to wait.
Only real appointments
Calu names only practices, times and types of appointment from Calenu’s directory.
In an emergency, 112
In an emergency, call 112. Urgent but not an emergency: 116117, around the clock and free of charge.
The emergency card
Which words show which card.
Certain words show a card with phone numbers. The card informs, and booking stays open.
Emergency
Words such as “chest pain”, “heart attack”, “shortness of breath”, “can’t breathe”, “stroke”, “paralysis”, “heavy bleeding”, “unconscious”, “seizure”, “allergic shock”, “overdose”, “poison”, “blue lips”, “weakness on one side” or “slurred speech”. And German ones such as “Brustschmerz”.
The card gives 112 and 116117.
Crisis
Words such as “suicide”, “kill myself”, “end my life”, “want to die”, “don’t want to live”, “better off dead”, “harm myself”, “self-harm” or “cutting myself”. And German ones such as “will sterben”.
The card gives the Telefonseelsorge, Germany’s crisis line, at 116 123 and 0800 111 0 111, and 112. In the app, 116117 is on it too. Calu on this website also gives 0800 111 0 222.
Seven topics with their own card
Signs in a baby or child, chest pain, trouble breathing, signs of a stroke, heavy bleeding, a sudden severe headache and severe belly pain.
The card says what matters for that topic and gives 112 and 116117.
Two words that mean something together
Each is everyday on its own, but not together. “Pregnant” with bleeding or severe pain. A baby, an infant or “three weeks old” with “fever”, a temperature, “floppy” or “not drinking”.
Then the emergency card appears with 112 and 116117, and for a baby often the card for children.
How Calu reads the words
In English and in German, upper or lower case. Also the way people type: ae for ä, ss for ß, with or without a hyphen, long words apart or together. One mistyped letter in a long word still counts, as in “unconcious”. For some signs it is enough for two words to appear anywhere in the same message, such as “chest” and “left arm”.
The app and the website know the same words.
A “not” changes nothing
“No chest pain” still shows the card. That is on purpose. A card too many costs a glance. A card missing because a “not” was misread costs more.
Measured
How well Calu spots an emergency.
of emergency sentences show the emergency card: 79 of 150. With the lists of September 30 it was 40 of 150.
of crisis sentences show the crisis card: 55 of 130. Before, it was 20 of 130.
of everyday questions show no card: 153 of 160.
emergency sentences show the emergency card.
crisis sentences show the crisis card.
112 and 116117 are on every screen where you look for help, whether a word matches or not. A word list does not recognize every way of putting things: for emergency and crisis sentences worded differently than expected, the card is often missing.
We test the lists with two kinds of test sentences. We use the development sets while writing the lists. They only show whether the lists do what we planned.
A different language model wrote the two blind sets from a short brief, 220 sentences each, without the lists, without earlier test sentences and without a list of situations. The lists were never tuned to their sentences. Our test program shows only how many of their sentences bring up the card. Only they tell how the lists handle sentences nobody foresaw. That is why they come first, added together.
A first blind set of October 1 was not blind enough: we knew some of its sentences when we extended the lists. So its figures are not shown here. It now counts as a development set.
The test sentences are made up, not messages from real people. Almost all of them are German: English sentences are not yet measured on their own.
Blind sets: 440 sentences together, measured on October 2, 2026 with the lists of September 30 and with those of October 2.
Report
A card was wrong?
Calu showed a card where none belongs? Or a card was missing? Write to us.
Send the sentence along if you like, ideally without names.