8 Financial Calculators
— Calculations That Stay in Your Browser

When to use it

After a consultation, the numbers do not stay in your head. You heard “you just pay this much a month” but come home without knowing the total. These tools let you enter the numbers yourself before signing.

• When you want to check the monthly payment and total interest after a loan consultation
• When you want to know when you will finish paying if you keep using card revolving credit
• When you want a rough idea of the tax before transferring a home or other property

The 8 calculators

To see the explanation and the input screen together, use the page for each purpose.

• Loan repayment calculator, Deposit & savings interest calculator
• Revolving credit calculator, Late payment interest calculator, Early repayment fee calculator
• Capital gains tax quick estimator, Gift tax quick estimator, Financial income tax quick estimator

💰 Loan repayment — Reflects principal, annual rate, term, repayment method and grace period. It shows the interest saved and the time shortened by extra monthly principal repayments, and the total cost including any additional costs you enter, such as stamp duty and guarantee fees.

🏦 Deposit & savings interest — Calculates deposits and installment savings, simple and monthly compound interest separately. It reflects base and bonus rates, payment at the start or end of the month and the subscription date, checks eligibility and limits for ordinary taxation, cooperative deposits and tax-free savings, and shows the tax by item and the after-tax amount.

💳 Revolving simulator — Reflects not only the balance, fee rate, payment ratio and minimum principal payment but also new monthly spending, extra payments and the number of days in the billing cycle. If it is not paid off within the chosen period, it shows the expected balance and a warning.

⚠️ Late payment interest — Enter the overdue amount, contract rate, penalty rate, and the start and planned repayment dates. It counts the days between the dates automatically and, across a year boundary, splits the calculation into 365-day and 366-day periods. It caps the penalty at 3 percentage points and the rate at the legal maximum of 20%.

✂️ Early repayment fee — It does not use a fixed default rate. Enter the actual rate from your agreement or the company's disclosure, plus the loan start date, maturity date, repayment date and fee-free amount, and it calculates a fee proportional to the actual days within the usual 3-year fee period.

🏠 Capital gains tax (quick) — Enter the transaction amounts, the purchase, contract and sale dates, the number of homes in the household, regulated areas, the period of residence and the land transaction permit date. It distinguishes the surcharge for 2 or 3+ homes in regulated areas after May 10, 2026, the regional transition periods for existing contracts with evidence of a down payment, short-term holding and unregistered rates, and exclusion from the long-term holding deduction.

🎁 Gift tax (quick) — Reflects the valuation on the gift date, relationship, gifts from the same person in the last 10 years and deductions used, debt assumed in the gift, marriage and childbirth deductions, generation-skipping and whether you file on time. When the conditions apply, it applies the 10-million-won aggregation threshold for prior gifts, the combined 100-million-won marriage/childbirth deduction and the 40% generation-skipping surcharge for minors receiving over 2 billion won. It does not calculate non-cash property before the value under tax law is confirmed.

📈 Financial income comprehensive tax (quick) — Separates domestic interest and dividends with tax withheld, dividends eligible for gross-up, overseas financial income without withholding, and tax-free or separately taxed income. It roughly estimates the 20-million-won threshold, comparative taxation, dividend gross-up and dividend tax credit, the 14–30% separate taxation of dividends from high-dividend companies in 2026, and local income tax.

How to use it

1. Choose a calculator from the list on the left (the row of buttons at the top on a phone). They are grouped into loans & credit, deposits & savings, and taxes.
2. Enter numbers in the input fields in the middle. Amount fields add commas automatically.
3. Press Calculate. If a field is empty or invalid, a message appears right there.
4. The results appear below in a table. Loans and revolving credit also show a month-by-month table.
5. Check term explanations and easily missed points in the Terms & cautions panel on the right.

What you will see

Borrowing 100 million won at 5% a year over 360 months (30 years) with equal payments gives a monthly payment of about 537,000 won, and interest over 30 years of about 93 million won. The numbers show that the interest is on a similar scale to the principal.

If 5 million won is 30 days overdue at a 6% contract rate plus a 3-point penalty, 9% a year applies and the late interest is about 37,000 won. When an adult child receives a gift of 300 million won from a parent, the tax base is 250 million won after the 50-million-won deduction, and with the filing credit the result is about 38.8 million won.

All three tax calculators are quick estimates. The capital gains calculator determines the usual multi-home surcharge and the basic requirements for temporarily owning two homes. Other special rules — inherited homes, registered rentals, rural homes and so on — are too complex, so it does not output an arbitrary tax amount. The gift tax calculator reflects marriage and childbirth deductions and gifts with assumed debt, but it cannot automatically confirm property valuations or whether a debt is recognized under tax law, and it blocks the start-up funds and family business succession special rules. The financial income calculator uses the tax base of your other comprehensive income but does not automatically determine the foreign tax credit, other credits and reductions, non-business lending income or actual withholding categories. Before filing, always use the Hometax (hometax.go.kr) simulation or consult a tax professional.

Loan and deposit results also differ from reality. Real loans carry additional costs such as handling fees, stamp duty and guarantee fees, and with a variable rate the monthly payment changes. Savings are calculated on the start- or end-of-month timing you chose, but real results depend on actual payment dates, each company's day count and rounding, and whether you meet the bonus conditions. Final eligibility for cooperative deposits and tax-free savings must be confirmed with the financial company. The results are not financial or tax advice.

How personal data is handled

These calculators calculate everything in your browser. Numbers you enter, such as loan amounts, property values and income, are not sent to the server and are not stored.

If you refresh or close the page, the numbers you entered disappear. Copy any results you want to keep into Financial Records yourself. But do not write account or card numbers anywhere — the calculations do not need them.

Frequently asked questions

Q. The result differs from what my bank told me.

A. The calculator reflects the principal, rate and term you enter, plus the grace period, extra repayments and additional costs. The financial company's actual payment dates, prorated first-month interest, rounding, rate changes and costs you did not enter can make the result differ. Follow the company's repayment schedule and notices for the exact amount.

Q. Can I use the capital gains tax result for my tax return as it is?

A. No. It reflects the usual multi-home surcharge and regulated areas, but it cannot settle exclusions from the number of homes, various special rules and reductions, or aggregation within the same year. Use it only to gauge the scale, and use the Hometax (hometax.go.kr) simulation or consult a tax accountant before filing.

Q. The late payment interest came out lower than the rate I entered.

A. That is because the usual 3-point penalty cap and the 20% legal maximum rate are applied in turn. There may be product-specific exceptions, so check your actual agreement as well.

Q. It says the revolving balance will not be paid off within 120 months.

A. The payment ratio is so low that the principal barely goes down. Check the actual fee rate and minimum payment in the card company's terms. If the terms are hard to read, copy the relevant part into Direct Input.

Q. Are the amounts I enter recorded anywhere?

A. No. All calculations happen in your browser. You can look up unfamiliar terms in the financial glossary (Korean).