Privacy

Your input stays in your browser

What you enter in a calculator is calculated in your own browser. Your input is then not sent to us, and we do not store or log it.

Only if calculating in your browser fails does our server help out. Your input is then sent to the server with every change, and the server uses it only to send back the result. Even then we do not keep or log your input; we only count, per calculator, how often this happens.

For health calculators we do not put your input in the link, so it does not end up in your history or in log files when you share it. For the other calculators your input is in the link after the # sign, so you can share a calculation; your browser does not send that part of the link to the server.

Google Analytics, only with your consent

If you consent to analytical cookies, we use Google Analytics, which we load through Google Tag Manager. Without that consent we load nothing from Google and the site sets no cookies. We do not use advertising networks or any other third-party trackers or analytics services.

Google Analytics then measures which pages you view and a few standard interactions: how far you scroll, whether you click a link to another site and whether you download a file. Google also sees data such as your browser, your device, your language, the site you came from and roughly where you are. What you enter in a calculator and the result are not sent to Google: in a link your input is after the # sign, and Google Analytics does not send that part.

For this Google Analytics sets two cookies: _ga and a cookie whose name starts with _ga_. They stay valid for 13 months. Google Analytics does not store IP addresses.

Google acts as our processor. Google may also process the data in the United States; that happens under the EU-U.S. Data Privacy Framework. We keep the data in Google Analytics for 14 months. Google signals are off, Google Analytics is not linked to any advertising product and we do not use the data for advertising or ad personalization. Sharing data with Google for other purposes is off.

The legal basis is your consent. You give or refuse it in the notice you see on your first visit, and you change or withdraw it through Cookie settings at the bottom of every page. If you withdraw your consent, we remove the Google Analytics cookies from your browser and the site no longer loads Google Analytics. If your browser sends the Global Privacy Control (GPC) signal, we treat it as a refusal: you see no message and we load nothing from Google. You can still allow it through Cookie settings.

Anonymous statistics

We count how often pages are viewed and calculators are used, to improve the site and to show which calculators are popular. For this, your browser sends small messages to our own server: which page you are viewing, whether you got a result or an error message, whether you looked at the explanation of the calculation or shared your result, and the name of the site you came from. What you enter in a calculator and the result are not sent. Nothing is stored on your device for this.

If you use the search box, the message also includes what you searched for: in lower case, without accents or punctuation and with # instead of digits, plus how many calculators were found (none, one or more) and which one you chose. If your search contains an @, / or :, or is longer than four words or 40 characters, the text is not sent.

Our server uses your IP address and browser type only at the moment such a message arrives. From your browser type it tells whether the message comes from a bot and whether you use a phone, tablet or computer. From your IP address and browser type it makes codes, with a key that exists only in memory and is thrown away every night; that is how it counts you only once a day and holds back too many messages. Your IP address and browser type are not stored anywhere. The codes exist only in memory, and without that key they can no longer be linked to an IP address. Cloudflare also passes on the country your connection comes from; we only count that as a total.

We only keep totals: per hour for 35 days and per day without an end date. With those totals we also keep the kind of site visitors came from (search engine, AI service, social network, email, this site itself or direct), the kind of device and the country. If you came from a site that fits none of those kinds, we keep the name of that site for 90 days, except on health calculators. Search terms are kept for 30 days; terms that are searched for more often are kept for 25 months as monthly totals. On health calculators your browser sends no error messages.

The legal basis is legitimate interest: improving the site, showing popular calculators and preventing abuse. Do you not want to be counted? Turn on Global Privacy Control or Do Not Track in your browser. Our server then throws your browser's messages away immediately, without using your IP address or browser type; we only count how many messages were thrown away like this.

What stays in your own browser

Your favorites, your choice of light or dark mode, your country choice and the units you pick yourself are stored in your own browser only (localStorage). They are never sent to us. You can remove them by clearing your browser data for this site.

Your cookie choice is stored there too, with the moment you made it, and is not sent to us either. If you clear it, or if we change what we do with your consent, we ask for your choice again.

Technical data

When your browser asks our server to help with a calculation, the server keeps track in its memory of how many such requests come from your internet address, to prevent abuse. That address does not go into a database or log file; it leaves the memory when the server restarts or once 10,000 other addresses have come in after it.

The site runs behind Cloudflare, which delivers and protects the pages and processes technical data such as your IP address for that purpose as a processor. Cloudflare is an American company, so this data may also be processed outside the European Union.

The site itself runs on a rented server. Its log files contain no IP addresses of visitors and are overwritten automatically. We make a backup of the database every night and keep it for just over two weeks; anything that disappears after a period mentioned above can stay in a backup for that much longer.

Your rights

The statistics contain only totals. We cannot find anything about you in them, so we cannot show, correct or delete anything either. You can object in advance, with Global Privacy Control or Do Not Track.

If you think we do not handle your data properly, you can file a complaint with a data protection authority; in the Netherlands that is the Autoriteit Persoonsgegevens.