Understanding Loan Interest in Japan

Interest is the price of borrowed money, quoted as a percentage a year but collected day by day. Japan adds a layer most countries lack: hard statutory caps on consumer-loan interest, plus a legal limit on how much unsecured credit licensed money lenders may extend at all. Know those rules and you can read any loan offer — from a mega-bank card loan to a consumer-finance storefront — in about ninety seconds.

How the rate becomes a charge

A lender quotes an annual rate (年率). The charge you actually pay is that rate applied to the balance you actually owe, for the days you actually owe it. On the standard daily-balance method, a ¥300,000 balance at 15% accrues roughly ¥123 a day (300,000 × 15% ÷ 365). Pay ¥100,000 off mid-month and tomorrow's accrual drops by a third. This is why the term of a loan matters so much more than intuition suggests: the rate sets the speed, the term sets the distance, and the distance is what you pay for.

Two loans at the same rate can still cost differently if fees sit on top — arrangement fees, guarantee company charges (保証会社)， card annual fees. Japanese consumer credit discloses these; the honest way to compare across offers with different structures is total repayment at the same term, which folds every cost into one number. The personal loan calculator runs exactly that comparison.

The statutory caps: 20% — 18% — 15%

The Interest Restriction Act (利息制限法) caps annual interest on consumer loans by principal size:

• Under ¥100,000: 20% per year
• ¥100,000 to ¥999,999: 18% per year
• ¥1,000,000 and above: 15% per year

Interest charged above the cap is not enforceable — the borrower can claim the excess back. The caps are why large bank card-loan limits are typically priced near the 15% line rather than the 18% one, and why ¥1,000,000 is a real threshold in product pricing, not a psychological one. The caps apply per loan contract, so several separate loans each under ¥1,000,000 can each legally carry 18%.

The one-third-of-income rule (総量規則)

Separately, the Money Lending Business Act's total quantity rule caps unsecured consumer credit from licensed money lenders at one third of the borrower's annual income, counted across all such lenders. A ¥6,000,000-a-year earner cannot hold more than ¥2,000,000 of money-lender unsecured debt in total. Bank loans and mortgages sit outside the rule — banks apply their own affordability screens instead. When a consumer lender rejects you for "quantity" reasons, this is usually the arithmetic at work, and no amount of explaining your bonus will move it.

What the term does to the total

On a ¥1,000,000 loan at the illustrative 8% rate, the equal instalment is about ¥31,300 over 3 years and about ¥20,300 over 5. The longer term frees ¥11,000 a month of cash flow — and costs roughly ¥216,000 of total interest instead of roughly ¥128,000. Nearly ¥90,000 of extra price for a comfort the borrower usually under-uses. The general law: at the same rate, total interest grows roughly with the square of the term, because both the smaller payments and the longer exposure compound. Use the loan calculator's term selector to watch it happen.

Interest in reverse: what lenders pay you

The same mathematics runs in your favour on deposits and investments — compounding at whatever rate the product pays, minus a flat withholding tax of about 20.315% on interest outside tax-free wrappers. The compound interest calculator shows the saving side; this guide's lesson is the same on both sides of the ledger: the rate is the speed, the term is the distance, and the total is what actually happens to your money. For what happens when several loans are merged into one, read debt consolidation basics next.