Privacy policy
The dates you enter are calculated and saved in your browser. This page lists everything else that happens when you visit — including the analytics and advertising scripts that load on every page.
At a glance
| Data | Where it goes | How to remove it |
|---|---|---|
| Dates and settings you enter in a calculator, and periods you log | Calculated in your browser and saved in this browser's local storage (plus session storage for the open tab, so a reload keeps your result). Not sent to our server, and not included in our analytics or ad requests. | Period calculator: "Start over" (inputs) and "Clear history" (logged periods). Period tracker: "Delete entire log". The other calculators keep their last entry until you clear this site's data in your browser settings, which removes everything. |
| Shared result links | The dates sit after the # in the link. Browsers don't send that part to our server. Anyone you give the link to can see those dates. | Delete the link where you shared it. |
| Page visits | Our self-hosted Plausible Analytics (analytics.lingyi.systems): page address without the # part, referring site, browser and device type, approximate location. No cookies. | Use a content blocker to stop the request; there is no per-visitor profile to delete. |
| Advertising requests | Google AdSense, loaded on every page. Google receives standard request data such as your IP address, browser and the page address (without the # part), and may set or read cookies. | Google Ads Settings; your browser's cookie controls. |
| Email you send us | Our mailbox at contact@onlineperiodcalculator.com. | Ask us to delete your messages. |
Your calculator data
- Where it is calculated: in your browser. The site is static pages — there is no server-side program that receives your inputs.
- Where it is saved: local storage in this browser, so the tool remembers your last entry, and session storage for the open tab, so a reload keeps the result on screen (cleared when the tab closes). Another device or browser will not see either.
- Shared and carried-over links: when you open a link that carries dates after the
#, the page reads them and removes them from the address bar before the analytics and ad scripts load, so those scripts see only the plain page address. - What we can't promise: any script running on a page can technically read that page. We keep your dates out of the requests we control and checked the requests the analytics and ad scripts actually send (October 2026); we don't claim more than that.
Analytics
Plausible Analytics runs from our own installation. Per Plausible's published data policy, it sets no cookies and no persistent identifiers, stores the page hostname and path (not query strings or the # part), and derives browser, device and approximate location from the request without storing raw IP addresses or user-agent strings; visitors are counted with an identifier that rotates daily. Page views, outbound-link clicks, file downloads and form submissions are recorded as events and shown to us as aggregate statistics.
Advertising, cookies & consent
This site has applied to Google AdSense. The AdSense script already loads on every page while Google reviews the site, and in our own test it contacted Google ad servers and set cookies on doubleclick.net before any ad was shown. Once ads run, Google and its partners may use cookies and similar identifiers to serve and measure ads, including ads based on your visits to this and other websites.
- Consent for the EEA, UK and Switzerland: a consent message is not live yet. We are adding Google's certified consent message and will update this page when it is on.
- Your choices now: turn off personalized ads in Google Ads Settings, block third-party cookies in your browser, or use a content blocker.
- How Google uses the data: How Google uses information from sites or apps that use its services.
What we don't do
We don't sell the dates you enter, don't require an account, and don't store health information on a server. If a feature ever needs more than in-browser storage, it will be off by default and explained on this page before it ships.
Deleting your data
On the period calculator, "Clear history" removes logged periods and "Start over" clears saved inputs; in the period tracker, "Delete entire log" removes its records. The other calculators remember your last entry on this device and have no delete button of their own — clearing this site's data in your browser removes those, everything above and the theme preference. That deletes every copy of your calculator data we know of, because no other copy is made. It does not delete what Google or our analytics server recorded about the visit itself — see the table above for those choices.