A small shift changes everything.

What this site is

Parallax is a small collection of free web calculators built around a single idea: a small shift in how you measure time changes how you experience it. We don't track quarterly KPIs or daily streaks. We track the questions that hit differently when you actually do the math — how old you'd be on Mars, how many weeks of an average human life are still ahead of you, where the years quietly disappear, what date your next planetary birthday falls on.

None of these tools are practical in the conventional sense. They won't help you book a flight, calculate a tip, or track macros. They will, occasionally, change how you spend a Saturday.

The name

The word parallax comes from astronomy. It describes the apparent shift in an object's position when viewed from two different angles. Astronomers use parallax to measure the distance to nearby stars: the tiny shift in a star's position as Earth swings from one side of its orbit to the other reveals how far away the star really is.

The metaphor is the whole site. Every calculator on Parallax is a small parallax shift — a different vantage point on something familiar. Your age viewed from Earth and viewed from Mars. Your life viewed as a number and viewed as a grid. The same time, two perspectives, and the gap between them is where the insight lives.

The four tools

Age on Other Planets — your age recalculated using each planet's orbital period as the unit of measure. You're 30 on Earth, 16 on Mars, just under 1 on Saturn. The same lifespan, eight different clocks.

Life in Weeks — a visualization based on Tim Urban's 2014 Wait But Why essay. Each row is a year, each square is a week. Filled squares are lived; empty ones are still ahead. Most people see roughly 4,000 to 4,680 squares total, depending on the lifespan they assume.

Time Dust — sleep, phone time, work, eating, commuting, waiting in line. Each is a small daily habit. Across a lifetime, they become the largest chapters. This calculator shows how many years each one consumes.

Cosmic Birthday — the exact Earth date your next birthday falls on, on every planet. Mercury birthdays come every 88 days. Saturn birthdays come about every 29 years. Most people only get one Saturn return in a full lifetime. Most people never get a Neptune birthday at all.

Why we built this

The honest answer is: because we wanted to use these tools and couldn't find a single place that hosted all four with a clean, ad-light interface that wasn't covered in pop-ups, mailing list nags, or affiliate spam. Most existing "age on Mars" calculators are buried inside spammy tool aggregators. The "life in weeks" visualization exists in dozens of forms, almost all of them static images. Time-use breakdowns get treated as productivity content, when really they're closer to philosophy.

Parallax is, deliberately, a hub for the curiosity-shaped questions — the kind you'd Google once a year, look at a result that's harder to read than it needs to be, and forget. We wanted the answers to feel finished. To live in a place that loaded fast. And to be free.

How the site is built

Every tool runs entirely in your browser. There is no backend, no database, no account system, and no analytics tracking individual users. The site is plain HTML, CSS, and a small amount of JavaScript. The math happens locally; the page loads instantly; it works offline once you've visited a page once. The only third parties involved are Google AdSense (display ads) and Vercel (hosting). We use a small amount of aggregate analytics through Vercel to know how many people visit, which pages they read, and how long they stay — no individual identification.

The site is hosted on parallaxhub.app, a custom domain on Vercel's free tier. Source code is public on GitHub if you'd like to see how anything is calculated.

How the site is paid for

Parallax shows display ads from Google AdSense. That's the only way it's funded. We don't sell anything, run an affiliate program, or collect email addresses. If you'd like to support the site without buying anything, turning off your ad blocker on this domain is the most useful thing you can do — it costs you nothing and keeps the site running.

If ads ever become intrusive, please tell us. The plan is to keep the site quiet enough that you forget the ads are there.

The data, and what we do with it

Your birthday is the only thing the calculators ever ask for. It is stored only in your browser's local storage so you don't have to retype it across the four calculators. It is never sent to a server we control. Read more on the Privacy page.

We do not collect names, email addresses, location data, or anything else. We don't have a way to identify you. We don't want one.

What's next

The current four calculators are the first batch. Future tools we're considering: a "Birthday of the Day" feature showing the cosmic birthday of a famous historical figure born on today's date; a more detailed "Life in Weeks" view that lets you mark milestones (school, jobs, moves, kids); and a "Sundays Left" countdown specifically for time with parents and grandparents. If any of these sound useful, or if you have a different curiosity-shaped question that needs a calculator, the contact page is the fastest way to reach us.

Who made it

A small team of two, making tools we wanted to use ourselves. We're not VC-funded, we don't have growth targets, and we don't plan to add a paywall. The site costs about $19 a year to run (the cost of the .app domain) and is funded by a small amount of AdSense revenue. If it ever stops being free, we'll tell you why first.

Questions, suggestions, complaints, or stories about how a calculator changed something for you — all welcome. Send a note.

Credits and acknowledgments

The "life in weeks" visualization originates with Tim Urban's 2014 essay Your Life in Weeks on Wait But Why. Oliver Burkeman's 2021 book Four Thousand Weeks: Time Management for Mortals is the best modern treatment of why this kind of math matters. The Stoic tradition — particularly Seneca's On the Shortness of Life and Marcus Aurelius' Meditations — has been thinking about this for two thousand years; we're just adding browser tabs to the conversation.

Orbital periods come from NASA's planetary fact sheets. Time-use defaults come from the U.S. Bureau of Labor Statistics' American Time Use Survey and academic studies on screen-time behavior.