Press
Everything here is checkable. If anything below is wrong, tell me and I will fix it rather than argue about it.
Live, updated continuously, and reported whether or not they are flattering. Methodology at /method.
What this is
Penny Millionaire is a month-long public experiment in exponential growth. Participants drop a penny, real or symbolic, and ask two other people to do the same. The site publishes the resulting branching factor live: the real number of people each participant actually brings.
Contributions are voluntary personal gifts to that month's featured participant. Participants are never paid and receive nothing for taking part or for inviting anyone. It is not a charity and nothing is tax-deductible.
Facts, with sources
- The last US penny struck for circulation was minted November 12, 2025, at the Philadelphia Mint, ending 232 years of production.
- Roughly 114 billion pennies remain in circulation. They are still legal tender and still spend.
- The Treasury has publicly encouraged Americans to spend their on-hand pennies to smooth the transition.
- The cent cost 3.69 cents to mint in FY2024.
- About 333 pennies per American, roughly $3.33 — about one jar.
- Legislation to end the cent permanently has passed one chamber and is pending in the other. It is not law.
A correction worth making in advance: the penny has not been discontinued, demonetized, or rendered worthless. Production for circulation stopped. Every cent already minted remains legal tender indefinitely.
The short version
After 232 years, they're retiring the penny.
Before it goes, let's do something ridiculous.
ONE PENNY.TWO PEOPLE.ONE MONTH.ONE MILLIONAIRE.
The arithmetic is famous. One person tells two, thirty times over, and you have more people than exist. Nobody has ever measured whether people actually do it. That number is on the front page and it updates live.
The Treasury asked Americans to spend their pennies. I'm asking you spend one here, and watch it grow.
What I will and will not say
- Will: publish every number, including the bad ones.
- Will: tell you exactly how the branching factor is computed and where it is biased.
- Will not: claim to be physically collecting coins. No coin moves. The penny is a unit, not an object.
- Will not: predict a total. The exponential table is arithmetic, not a forecast, and it is labelled as such everywhere it appears.
- Will not: discuss my personal finances. The experiment is the story.
Images
Free to use with credit.
The cat is Tito. He appears in the artwork because he was there. He died shortly before launch, and he is not part of the pitch.
Contact
One person answers this. Replies are usually same-day.