The Fine Print

Privacy Policy

Last updated 6 September 2026

The Dollar Time Machine is a single-page calculator. It works without an account, without a login, and without knowing who you are. The only personal information it ever holds is an email address you typed in on purpose.

Information we collect

• Email addresses, and only through the one opt-in form on the site. If you enter your address to receive the monthly update, the address is the only thing submitted — nothing about which yardstick you were looking at, which years you had chosen, or what you did on the page goes with it. Nothing at all is collected if you close the form or dismiss it.
• Anonymous usage data and analytics. Google Analytics records aggregate visit data — pages viewed, approximate region, device and browser type, referring site — and Netlify, which hosts the site, keeps standard server request logs. This data is anonymous and is not tied to your email address or to any identity.

The calculator also keeps one small value in your browser’s own local storage: whether you have already answered or dismissed the email prompt, so it stops asking. That stays on your device and is never transmitted to us.

How we use your data

Email addresses are used to send the monthly index updates you asked for, and to send emergency alerts — the rare case where something needs to reach subscribers outside the normal monthly rhythm. Anonymous usage data is used to improve how the app works: which yardsticks people actually reach for, which parts of the page get used, and what to fix or build next.

That is the whole list. Your address is not used for unrelated marketing, and it is not used to build a profile of you.

Third-party sharing

We do not sell personal data. Your email address is never sold, rented, traded, or handed to advertisers or data brokers.

Anonymous aggregate metrics — totals and trends such as monthly visitors, subscriber counts or which yardsticks are most popular — may be shared with sponsors. These figures describe the audience as a whole and cannot be used to identify you or to contact you.

A small number of service providers necessarily process data on our behalf in order for the site to function: Netlify hosts the site and receives form submissions, Google Analytics provides the anonymous analytics described above, and the newsletter itself is delivered through Kerry’s Substack. Each handles data under its own privacy terms.

Cookies and analytics

Google Analytics sets cookies to tell repeat visits apart from new ones. The site sets no advertising cookies of its own and does not track you across other websites. You can block or clear these cookies in your browser settings, or use a browser-level analytics or tracking blocker, and the calculator will keep working exactly as it does now.

Your choices

Giving us an email address is entirely optional — every feature of the calculator, including the share cards, works without one. If you have subscribed and change your mind, the unsubscribe link in any email removes you from the list, and you can ask to have your address deleted outright.

Changes to this policy

If this policy changes, the revised version appears on this page with a new date at the top. Material changes affecting subscribers will be mentioned in an index update rather than made quietly.

Getting in touch

Questions about this policy, or a request to see or delete your data, can be sent by replying to any index update or through Kerry’s Substack.