Privacy

This site uses Cloudflare to deliver pages and measure browser traffic, plus self-hosted Umami for cookieless page and usage statistics. Calculator inputs and copied contents stay in your browser. The statistics section below explains the data, retention and browser controls.

The German version of this page is the legally binding one.

Controller

HelpfulCalculator – Sören Striewski c/o Autorenglück #35312 Albert-Einstein-Straße 47 02977 Hoyerswerda Germany

Email: contact@helpfulcalculator.com

Server log files

When you request a page, your browser transmits technically necessary data that the host records in log files: IP address, date and time, the address requested, the amount of data transferred, browser type and operating system, and the previously visited page if your browser sends it.

The legal basis is Art. 6(1)(f) GDPR. The legitimate interest is the technically sound operation of the site and the defence against attacks. This data is not combined with other sources and is not evaluated to analyse user behaviour.

Hosting

This site is served on Cloudflare Pages by Cloudflare, Inc., 101 Townsend Street, San Francisco, CA 94107, USA. When you request a page, Cloudflare processes the server log files described in the section above in order to deliver the site and to defend against attacks.

Cloudflare is a processor under Art. 28 GDPR. The processing is governed by Cloudflare’s data processing addendum, which incorporates the European Commission’s standard contractual clauses.

Data may be transferred to the United States. Cloudflare, Inc. is certified under the EU-US Data Privacy Framework; the transfer relies on that certification and, in addition, on the standard contractual clauses.

Log files are retained for Cloudflare’s default retention period and deleted afterwards.

Website statistics

Umami runs on the controller’s Home-Server. The browser sends the public page pathname, at most the referring site’s origin, and fixed event/tool identifiers for valid calculator use, successful result-link copying or engaged article reading. Queries, fragments, calculator values, copied text, email addresses, uploaded files and filenames are excluded. Result-link copies are reported separately from the four core meaningful actions; no count proves a human visitor.

For development diagnostics, fixed categories also record the first real calculator edit, rendered input/calculation errors, failed result-link copies, calculator navigation and a completed search with no results. Search text, error messages and entered values are excluded; these diagnostics remain separate from successful meaningful use.

Additional diagnostics record visible page-time milestones (30, 60 and 180 seconds after one trusted interaction), content-viewport milestones (25, 50, 75 and 90 percent), copy/download attempts and calculator resets, and existing language, outbound and search controls. Only controls available on the page are observed. Outbound destinations are not sent. Visible time is not continuous attention, viewport depth does not prove reading, and a request does not prove a completed copy, navigation or saved download. These events do not change the four core meaningful actions.

IP address and browser information are processed transiently to form pseudonymous session and visit identifiers. Raw IP addresses are not fields in normal analytics event records. Umami does not set analytics cookies or a persistent local visitor ID. The TLS collector is reached through Tailscale Funnel.

Individual analytics records are retained for 180 days; daily aggregates for 24 months. Encrypted backups are retained for 7 days, so deleted records may remain in a protected backup until its expiry. Aggregates do not contain visitor identifiers.

Do Not Track, Global Privacy Control and our explicit internal/test markers disable this site’s Umami integration. The “Turn off Umami in this browser” control stores only analytics.disabled and umami.disabled, each with the value 1, which prevent future Umami collection on this domain. Removing the disable keys restores the ordinary privacy checks. This Umami setting applies separately from Cloudflare’s independent traffic measurement. Questions or objections can be sent to the controller’s contact address above.

Cloudflare Web Analytics supplies a separate browser traffic and performance reference. It is subject to Cloudflare’s Web Analytics privacy information. Its totals and Umami visits use different collection rules and are not a bot percentage or a count of proven people.

Cookies

This site sets no cookies.

Local storage

Browser storage holds calculator preferences and, when you choose it, the Umami disable setting:

These values are not transmitted to us or to anyone else; they stay in your browser and contain no identifier that could recognise a device or a person.

hc-unit-system is created only when you use the unit switch yourself. The legal basis is section 25(2)(2) TDDDG (the act was called TTDSG until it was renamed on 14 May 2024; the section number did not change): the storage is strictly necessary to provide the service you explicitly requested — the calculator in the unit system you chose. No consent is required for this, which is why there is no cookie banner.

hc-recent is different, and we treat it differently. A list of pages you have visited is a convenience, not a necessity, so it is off until you switch it on. Nothing is written until you press the button on the home page that offers it; before that press, no such key exists and this site stores nothing about where you have been. That press is the consent required by section 25(1) TDDDG. The same block offers a button that stops the recording and deletes the list.

hc-lang-hint is written once, at the moment you dismiss the notice offering this page in the other language — it records only that you dismissed it, so it does not come back. It holds the single value off and nothing else: no page address, no time, no identifier. Its legal basis is section 25(2)(2) TDDDG as well, on the same reasoning as the unit switch: acting on a preference you expressed by clicking is the service you asked for.

Your browser settings can delete the stored values at any time.

What you type into a calculator

Everything you enter into a calculator is computed in your browser. Calculation does not send the inputs to our server. Private inputs are kept out of newly generated share links. An incoming or older link can nevertheless contain inputs in its URL; opening or reloading it sends that URL to the hosting server, where it may be logged.

Publicly shareable fields can be included in a result URL. Anyone receiving that URL can read those values. Check the address before sharing sensitive information.

Links to sources

Every calculator names the source of its figures. Those links lead to other people’s servers. Only when you click one does that provider learn your IP address; their own privacy policy governs what happens then. Those linked servers are contacted only when you open their links.

Your rights

You have the right of access (Art. 15 GDPR), rectification (Art. 16), erasure (Art. 17), restriction of processing (Art. 18), data portability (Art. 20), and objection to processing based on legitimate interests (Art. 21). Please use the email address above.

You also have the right to lodge a complaint with a supervisory authority (Art. 77 GDPR) — for our registered seat, the Saxon Commissioner for Data Protection and Transparency.