Privacy policy

The short version

• Your calculator inputs never leave your browser. Every formula on this site runs locally in JavaScript. The dimensions you type are not transmitted anywhere, not stored, and not visible to us.
• There are no accounts, no sign-in, no newsletter and no contact form.
• We use two third parties. Google AdSense serves the advertising, and it does set cookies. PostHog counts pageviews, and it is configured to store nothing on your device at all. Both are described below, with the opt-out links.
• We do not sell personal information, and we do not share it with data brokers.

Who is responsible

The data controller is Eioto Studio. For anything on this page, including requests about your own data, write to tsuyoshi.gt@gmail.com. A person reads that address; expect a reply within a few working days.

What the calculators do with your numbers

Each calculator is a pure function that is loaded into your browser and evaluated there as you type. The page is static HTML — there is no application server to send anything to. If you enter the dimensions of your driveway, that stays between you and your device. Closing the tab discards it.

Server logs

The site is hosted on Netlify, which serves the files and keeps standard request logs. Those logs contain your IP address, the page requested, the time, your browser's user-agent string and the referring page. They exist so the host can serve traffic, block abuse and keep the site up. We do not use them to build a profile of you, and we do not combine them with analytics or advertising data. Netlify's own handling of that data is covered by Netlify's privacy policy.

Advertising, and the cookies that come with it

Pages on this site carry display advertising supplied by Google AdSense. This is how the site is paid for; there is no paywall and nothing is sponsored content.

• Google and its advertising partners use cookies and similar device identifiers to serve ads, to limit how often you see the same ad, and to measure whether an ad worked.
• Google uses its advertising cookie — the DoubleClick / __gads family — to serve ads based on your visits to this and other sites. Depending on your settings and your location, those ads may be personalised.
• Third-party vendors that Google works with may also place cookies. We do not control those vendors individually and we receive no personal data from them — only aggregate earnings and impression counts.

You can turn personalised advertising off for your Google account and device at google.com/settings/ads. Doing so does not remove ads; it makes them non-personalised. Google's own description of how it uses data from partner sites is at policies.google.com/technologies/partner-sites, and its advertising technologies are documented at policies.google.com/technologies/ads. You can opt out of personalised advertising from many vendors at once via aboutads.info or Your Online Choices in Europe.

Analytics

We use PostHog to count pageviews and to see which calculators people actually use, so we know what to build next. It is configured deliberately narrowly:

• Pageviews and page-leave events only — no automatic capture of clicks or keystrokes.
• No session recording or screen replay. It is switched off in code.
• No identified user profiles. Events are anonymous unless we would explicitly identify someone, and this site never does — there is nobody to identify.
• Nothing is stored on your device. PostHog is configured with in-memory persistence, so it writes no cookie and no local storage entry. The identifier it uses lasts as long as the page is open and is discarded when you leave.
• The trade-off is ours, not yours: because nothing persists, we cannot tell a returning visitor from a new one. We can see that a page was viewed and which calculator it was, and that is all we need.

PostHog processes this on servers in the United States. Their handling is covered by PostHog's privacy policy. If you would rather not be counted, you have three ways to stop it and none of them break anything on the site: a browser-level tracker blocker, a Do Not Track setting, or a Global Privacy Control signal. The last two are checked in our own code before the analytics library is even downloaded — if either is set, no request to PostHog is made at all.

Cookies in summary

This site sets no cookies of its own, for any purpose. There is no login and no preference to remember, and analytics is configured to store nothing, as described above. That leaves exactly one source of cookies:

• Advertising — set by Google and its partners on their own domains, for ad delivery, frequency capping and measurement. Non-essential, and subject to consent where consent is required.

Your browser controls those. Blocking or clearing them changes nothing about how the calculators work, because the calculators never needed a cookie in the first place.

If you are in the EU, UK or Switzerland

Under the GDPR and the UK GDPR the legal bases we rely on are:

• Consent for advertising cookies. Where consent is required, Google's certified consent management prompt collects and records it before personalised ads are served, in line with Google's EU user consent policy. If you decline, ads are served non-personalised.
• Legitimate interest for keeping the site available and secure — the host's request logs described above — and for the aggregate traffic measurement described under Analytics. We do not show a separate analytics prompt, and under the ePrivacy rules we do not need one: storing or reading anything on your device is what triggers that requirement, and our analytics stores nothing at all. No profile is built, nothing is shared onward, and we respect Do Not Track and Global Privacy Control without being asked twice. If you object, either signal stops it, as does any tracker blocker.

You have the right to access the personal data we hold about you, to have it corrected or erased, to restrict or object to processing, to withdraw consent at any time, and to lodge a complaint with your supervisory authority. In practice we hold very little: no account, no address book entry, nothing you typed into a calculator. Write to tsuyoshi.gt@gmail.com and say what you want done and we will act on it, or tell you honestly that we never had the data in the first place.

Data may be processed in the United States by the providers named above. Those transfers rely on the European Commission's standard contractual clauses and, where the provider is certified, on the EU–US Data Privacy Framework.

If you are in California

We do not sell personal information and we do not share it for cross-context behavioural advertising in exchange for money. Advertising cookies set by Google may still constitute "sharing" under the CCPA as amended; the Google ad settings link above is the effective opt-out, and a Global Privacy Control signal sent by your browser is honoured by Google. You may also email us to exercise your rights, and we will not discriminate against you for doing so.

How long anything is kept

• Calculator inputs — never stored, so nothing to keep.
• Host request logs — retained by Netlify under their own retention schedule. We do not export or archive them.
• Analytics events — retained in PostHog under that project's retention setting. We keep no copy anywhere else and do not use the events for anything but aggregate counts.
• Email you send us — kept while the conversation is useful, then deleted.

Children

This site is about buying building materials. It is not directed at children, and we do not knowingly collect information from anyone under 16. Ad serving on this site is not configured for child-directed treatment because the audience is adult homeowners and trades.

Changes

If what the site does changes, this page changes with it, and the review date below moves. We will not quietly widen what we collect. The current version is dated 2026-07-30.