Privacy policy
Updated 8 October 2026
In short: Calcuralab needs no registration and uses no advertising. The values and expressions you type are not sent to a server; the calculations run in your own browser. Without your consent the site keeps your settings only for the duration of this tab’s session. Remembering your settings and progress permanently, and Google Analytics statistics, are used only if you allow them, and you can change your choice at any time.
1. Controller
The controller of this website is Atte Mäkinen. For privacy matters you can contact us by email at attm7358@gmail.com.
2. What data is processed, why and on what basis
2.1 Delivering the site and security
The site is published on the service of Cloudflare, Inc. (Cloudflare Workers). When you open the site, your browser sends the usual connection data to Cloudflare’s servers: your IP address, the requested address, the type of browser and device, and the time of the request. This data is needed to deliver the site to you and to keep the service secure (for example, to prevent abuse and denial-of-service attacks). Cloudflare processes the data to provide the service, and as its own controller for the security and operation of its network. You can read more in Cloudflare’s privacy policy.
Legal basis: legitimate interest (GDPR Art. 6(1)(f)): delivering the site and maintaining its security.
2.2 Data stored in your browser
The site uses your browser’s storage for three purposes. See the exact list in Cookies and storage.
- Necessary: remembering your choice, and the site’s files (cache and service worker) that let the site work quickly and without a network connection. Your language, theme and other choices are also kept for the duration of this tab’s session. These do not require consent because they are needed to provide a service you have requested (Directive 2002/58/EC, Art. 5(3); Finnish Act on Electronic Communications Services 917/2014, Section 205).
- Settings and progress: if you allow them, your browser remembers when you return your chosen language, theme and number of decimals, hiding of explanations, the topics and functions you viewed last, and your exercise history and electricity progress. The data is stored only in this browser and is not sent to anyone. Legal basis: consent (Directive 2002/58/EC, Art. 5(3); Act 917/2014, Section 205). Without consent this data is kept only for the duration of this tab’s session.
- Statistics: Google Analytics, see 2.3.
2.3 Statistics (Google Analytics)
If you allow statistics, the site loads Google’s Google Analytics 4 service and sets cookies (_ga and _ga_…) in your browser. Without your consent
nothing is loaded from Google and no cookies are set. The statistics help us understand which parts of the site are used and how to improve it.
Google Analytics receives the following data: a random identifier in the cookie, the pages viewed (the topic address and title, not the expressions you type), page view times and visits, your browser, device, language and approximate location (country or city; Google Analytics 4 does not store IP addresses). Google signals and ad personalisation are turned off, and the data is not used for advertising. The site does not send your name or email address to Google Analytics.
The statistics are processed by Google Ireland Limited (EU) and Google LLC (United States) as the service provider. The site owner is the controller of the data. Data may be transferred outside the European Economic Area; transfers rely on the EU–U.S. Data Privacy Framework, which Google is certified under, and where necessary on the European Commission’s standard contractual clauses. More information: Google’s privacy policy.
Legal basis: consent (Art. 6(1)(a) and Act 917/2014, Section 205). You can withdraw your consent at any time in Cookie settings; withdrawing stops the sending of data and deletes the Google Analytics cookies from this browser. Withdrawal does not affect the lawfulness of processing carried out before it. If your browser sends a do-not-track signal (Do Not Track or Global Privacy Control), statistics are not used.
2.4 Contacting us
If you send the site owner an email, your message and your address are processed so that we can reply and deal with the matter. Legal basis: legitimate interest in replying to enquiries (Art. 6(1)(f)).
2.5 Sharing
The share button opens your device’s own share function or copies the page address to the clipboard. The address is not sent to the site owner.
3. Recipients and transfers outside the EU
Data is processed to deliver the site by Cloudflare, Inc. (United States) and, only with your consent, for statistics by Google Ireland Limited and Google LLC (United States). Data may therefore be transferred outside the European Economic Area. Transfers rely on the EU–U.S. Data Privacy Framework, which both companies are certified under, and where necessary on the European Commission’s standard contractual clauses. Data is not sold or disclosed for marketing purposes.
4. Retention
- Connection data (Cloudflare): in line with Cloudflare’s practices. The site owner does not store it.
- Your consent choice: 12 months, after which you are asked again.
- Settings and progress stored in your browser: once allowed, until you delete them (see below) or clear your browser data; without consent, only for the session.
- Google Analytics cookies: at most 13 months. Statistics collected in Google Analytics are kept for at most 14 months.
- Emails: for as long as handling the matter requires, and no longer than 12 months after the last message, unless the law requires longer retention.
5. Your rights
Under the GDPR you have the right to access your data, to have it rectified or erased, to restrict or object to processing, and to data portability (Art. 15–21). You can also withdraw any consent you have given at any time (Art. 7(3)). Because the site can be used without identifying yourself, the site owner is usually unable to link data to you (Art. 11). You can send requests to attm7358@gmail.com; we will reply without undue delay and within one month at the latest.
You also have the right to lodge a complaint with a supervisory authority. In Finland, the supervisory authority is the Office of the Data Protection Ombudsman.
Personal data is not used for automated decision-making or profiling.
6. Children
The site is intended for studying by people of all ages. It does not ask the user for data, and using it requires no registration. Statistics and permanent remembering are used only with consent. A minor should allow them only together with a guardian.
7. Cookies and storage
Your choice is shown in the consent bar on your first visit. You can change it at any time. The site stores the following data:
| Storage | Category | Purpose | Kept |
|---|---|---|---|
calcuralab.suostumus (localStorage) | Necessary | Remembering your consent choice. | 12 months |
Cache (derivaatta-…) and service worker | Necessary | The site’s files, so that the site works quickly and without a network connection. Updated when the site is updated. | Until you delete it |
derivaatta.kieli, derivaatta.teema, derivaatta.desimaalit, derivaatta.selitykset | Settings and progress | The chosen language, theme (light or dark), number of decimals and hiding of explanations. | If allowed, until you delete it; otherwise for the session |
derivaatta.tila | Settings and progress | The topic and tab you viewed last, and the simulator’s values, such as the function you typed and the positions of the controls. | If allowed, until you delete it; otherwise for the session |
derivaatta.tehtavat, sahko.* | Settings and progress | Exercise history, and progress and choices in the exercises and electricity sections. | If allowed, until you delete it; otherwise for the session |
derivaatta.eleohje | Settings and progress | Whether you have seen the graph’s usage hint. | If allowed, until you delete it; otherwise for the session |
_ga, _ga_… (cookies, Google) | Statistics | A random Google Analytics identifier and session state for anonymous usage statistics. Set only if you allow statistics. | At most 13 months |
You can change your choice with the button below. You can also delete all the site’s data from this browser with the other button, or in your browser’s settings (site data and cache). If you block storage in your browser, the site still works but does not remember your choices.
8. Changes
We update this policy when needed, for example if new features are added to the site. The current version is always on this page, and the update date is shown at the top. Copyright, terms of use and other matters are on the Terms and copyright page.