How Savings Grow in Japan
Japanese savings live in two main containers. The ordinary deposit (普通預金) pays a variable rate, lets you withdraw at any moment, and is where salaries arrive and daily life happens. The time deposit (定期預金) locks a sum for a fixed term at a fixed rate, usually earning more for the patience. This calculator is deliberately container-agnostic: you enter the rate your product actually pays, the amount you start with, and what you add each month, and the page projects the balance year by year with the compounding frequency you select. At ordinary-deposit-style rates the interest line will look thin — that honesty is the point.
Two protections and two frictions shape real returns. On the protection side, the Deposit Insurance Corporation of Japan covers principal plus interest up to ¥10,000,000 per depositor per bank — spreading large sums across institutions is the classic response. On the friction side, interest income from deposits is generally subject to a flat withholding tax of about 20.315% (income tax, resident tax and the reconstruction surtax), and the projection here shows pre-tax growth, so discount the interest line accordingly when it matters. Both effects are easy to hold in your head once the calculator has shown you the raw arithmetic.
Why the rate is an input, not a fact
Deposit rates in Japan have moved through decades that future generations will study — long years near zero, and a recent period of change as policy shifted. A calculator that hard-coded "today's" rate would be quietly wrong within months. So this page never states one: the 0.50% pre-filled is labelled as an illustrative example, not a market rate, and every figure recomputes the moment you type the rate your bank actually publishes for your product. What the page contributes is the structure — how deposits, interest and time combine — which stays true whatever the rate column says.
From saving to investing
Once an emergency fund of a few months' expenses sits in ordinary deposits, the next yen saved faces a choice: keep it in deposits, where the nominal return is small but the balance is insured, or move it toward investments, where the range of outcomes is wider in both directions. Japan's tax-free wrappers changed the arithmetic of that choice — the reformed NISA (from January 2024) allows ¥3,600,000 of purchases a year within an ¥18,000,000 lifetime ceiling. The Investment Growth Calculator runs that side of the decision, and the saving and investing guide walks through the whole ladder.
Frequently Asked Questions
What interest rate should I enter?
The rate your bank or institution publishes for your specific product and term. The 0.50% pre-filled is an illustrative example only — NOT a current Japanese market rate. Finance Atlas never pre-fills a market rate, because rates move and stale numbers mislead.
Is my deposit protected?
Principal plus interest is protected up to ¥10,000,000 per depositor per bank by the Deposit Insurance Corporation of Japan. Amounts above that limit are not covered — spreading across banks is the conventional response for large sums.
Does the projection include tax?
No — it shows pre-tax growth. Interest on deposits in Japan is generally subject to a flat withholding tax of about 20.315% (including the reconstruction surtax). If the tax matters to your decision, discount the interest line accordingly.
Which compounding frequency should I choose?
Match your product: many Japanese time deposits pay simple interest at maturity rather than compounding, while ordinary deposits credit interest periodically. If you are unsure, run the projection twice — the gap between frequencies at deposit-level rates is small, and seeing it is useful.
Should I save or invest?
Deposits are insured and quiet; investments are neither, but their long-run expected return is higher. The usual sequence is an emergency fund of several months' expenses in deposits first, then long-horizon money in tax-free wrappers such as NISA. The Investment Growth Calculator and the saving-and-investing guide cover the second step.
Related Japan Calculators & Guides
- Japan Compound Interest Calculator — the mathematics of growth
- Japan Investment Growth Calculator — projecting invested money
- Guide: Saving and Investing in Japan
- Guide: Understanding Loan Interest in Japan — compounding in reverse
Disclaimer: Finance Atlas is not a licensed bank, lender, card issuer or financial adviser in Japan. This calculator provides educational estimates only and does not constitute financial advice or a credit offer. Confirm exact figures with your lender, issuer or bank.