Calculator
Compounding-interest calculator
Estimate how a starting amount plus monthly investing could grow over time in yen, with a yearly breakdown.
Tools
Simple calculators for calm planning.
These tools are here to make the numbers feel less abstract. They are designed for beginners in Japan who want a plain-English way to test a few simple investing scenarios.
Available now
Live tools, with more to come
Keep expectations modest: these are educational planning aids, not forecasts or personal advice.
Calculator
FIRE / retirement number calculator
Work out a rough retirement target in yen, compare it with your projected portfolio, and see whether your current plan looks on track.
Future tool
NISA contribution planner
A simple helper for thinking about contribution pace, annual limits, and how to spread regular investing across the year.
Future tool
Expense tracker
A simple way to understand your real living costs so you can estimate the spending number behind a 4% rule style FIRE target more clearly.
How to use these
Useful for rough planning, not certainty
A calculator can help you see the basic trade-offs: how much comes from your own contributions, how much might come from growth, and how much difference time can make.
It cannot tell you what markets will do next, and it cannot replace personal tax, legal, or investment advice. Think of these tools as a simple first pass.
Important note
Educational tools only
All figures shown here are estimates based on the assumptions you enter. Real returns vary, fees matter, taxes can matter outside tax-sheltered accounts, and your personal situation may be different.
Try the FIRE / retirement number calculator