Yen & Zen is a small, independent project: a growing collection of practical calculators and converters for anyone living in or travelling to Japan. The site is built and maintained from Yokohama by a civil engineer working in renewable energy who has spent years navigating Japan's paperwork, taxes and quirks as a non-Japanese resident in a Japanese-Spanish household.
Every tool here exists because we needed it ourselves. The Japanese era converter, the kazoedoshi calculator, the JR Pass break-even—these are the tiny, repeated computations that come up over and over when your life or trip touches Japan, and that the bigger generic calculator sites tend to either get wrong or wrap in three pages of ads.
Our promise is simple: every calculator is free, gets to the answer fast, works on phones, and explains the underlying rule in plain language. No accounts. No newsletters. No "premium tier".
How the site is funded
Yen & Zen is funded by display advertising (Google AdSense) and—on a few specific pages where it's relevant—affiliate links to services like rail passes or currency transfer. We never recommend a service we wouldn't actually use, and affiliate placements are always disclosed on the page itself.
Accuracy
We pour real care into the math behind these tools and cite official sources (national tax agency, JR Group, etc.) where applicable. That said, tax codes, fares and rules change. Always confirm important figures with the official source before making a financial decision.
Get in touch
Spotted a bug, got an idea for a calculator, or just want to say hi? See the contact page.