Savings Interest Calculator
Enter rate and term to see the maturity amount of a Korean deposit or installment savings after Korea’s 15.4% interest tax, with tax-free and credit-union options.
Loading the tool…
User reviews
No reviews yet. If you’ve used this tool, be the first to leave one.
Savings Interest Calculator: complete guide
Walk through the steps and examples, or jump straight to the topic you need.
At a glance
- Product types
- Deposit (put the money in all at once) and installment savings (put money in every month).
- Interest method
- Choose between simple interest and monthly compound interest.
- Tax
- Choose from the standard rate of 15.4%, the cooperative deposit rate (1.4% for accounts opened through 2025, 5.9% for 2026, 9.5% for 2027 and later), or tax-free. These are Korean rates.
- Installment calculation
- For each installment, interest accrues only for the remaining period.
- Cross-check
- It checks whether principal plus after-tax interest matches the maturity payout.
- Comparison
- For installment savings, it compares with putting the same amount in all at once.
- Limit
- It calculates periods up to 600 months.
- What it doesn't do
- It does not fetch real product rates or recommend products.
How to use Savings Interest Calculator
Choose deposit or installment savings
Choose deposit if you put in a lump sum once, or installment savings if you put money in every month. Depending on the type, the amount field is labeled as the amount to deposit or the amount to deposit each month.
Choose the interest method and tax
Choose simple or monthly compound interest as written in the terms of the product you opened. Savings and deposits in Korea are often simple interest. The standard tax rate is the default; please check the conditions of your account for preferential or tax-free eligibility.
Enter the amount, rate, and period
Enter the annual rate before tax. The period is in months. If a value is invalid, it does not calculate and shows the reason.
Check the maturity payout
Principal, interest before tax, tax, and interest after tax appear in order. For installment savings, it also shows how much the interest differs from putting the same amount in all at once.
What it’s good for
It also shows why installment savings interest is small
If you put 100,000 KRW a month into a 3% per year installment savings account for a year, the interest is 19,500 KRW, not 36,000 KRW. That is because only the money from the first month earns twelve months of interest, while the money from the last month earns just one month's worth. This tool compares it with putting the same principal in all at once from the start and writes down how big the difference is. You haven't misread the rate.
It shows the amount after tax
Interest is taxed. You can calculate with the standard tax rate (15.4%), the rate for deposits at Korean cooperative financial institutions (1.4%, 5.9%, or 9.5% depending on the year you open it), or tax-free, and the rate is shown on screen. It also checks for itself whether principal plus after-tax interest matches the maturity payout, so it is easy to follow where and how much was deducted.
Worked examples
Installment savings · 100,000 KRW per month · 3% per year · 12 months
Simple interest · standard taxPrincipal 1,200,000 KRW
Interest before tax 19,500 KRWDeposit · 10 million KRW · 3% per year · 12 months
Simple interest · standard taxInterest before tax 300,000 KRW
Tax 46,200 KRW
Maturity 10,253,800 KRWWhy the results differ at the same rate
Swipe the table sideways to see the rest.
| Type | Period interest accrues | Result |
|---|---|---|
| Deposit | The whole period | Close to the stated rate |
| Installment savings | From each deposit to maturity | Feels like about half of a deposit |
| Monthly compounding | Interest earns interest again | Slightly more than simple interest |
When the result isn’t what you expected
The installment savings interest comes out too small
That is normal. Money put in the last month earns only one month of interest. The difference from putting the same amount in all at once is written below the result, so compare them.
It differs from the bank's calculation
The payment date and the interest calculation reference date differ by bank. This tool calculates by month, so a difference of a few days can change the amount by a few won.
I don't know how much the tax is
Usually it is the standard rate. For deposits at Korean cooperatives such as credit unions (Shinhyup), community credit cooperatives (Saemaul Geumgo), and agricultural cooperatives (Nonghyup), the rate is lower up to 30 million KRW per person across all cooperatives, and depending on the year you opened the account it is 1.4% (the special rural development tax only) through 2025, 5.9% for 2026, and 9.5% for 2027 and later. The old tax-favored comprehensive savings (9.5%) is closed to new accounts. Please check what you were told when you opened the account.
I don't know whether it is compound or simple
Unless the terms say compound, treating it as simple interest is closer to reality. You can also switch between the two methods to see how much they differ.
Key terms
- Simple interest
- A method where interest accrues only on the principal.
- Monthly compound interest
- A method where the interest added each month earns interest again.
- Interest income tax
- The tax on interest. In Korea, 14% income tax plus 1.4% local income tax, a total of 15.4%, is common.
- Maturity payout
- The amount you actually receive: principal plus after-tax interest.
Savings Interest Calculator FAQ
Should I choose simple or compound interest?
Choose the method written in the terms of the product you opened. Savings and deposits in Korea are often simple interest. Unless it says compound, calculating with simple interest is closer to reality.
What if the tax rate changes?
The tax rate is not fixed; it is something you choose. This tool does not judge preferential or tax-free eligibility, so please check the conditions of your account yourself.
It differs from the bank's calculation by a few won
The payment date and the interest calculation reference date differ by bank. This tool calculates by month, so it can differ from the real payout by a few won.
How much do I get if I cancel early?
It is not calculated. The early-termination rate differs by product and is usually much lower than the contract rate. You need to check with the bank directly before canceling.
Is Korea's comprehensive financial income taxation reflected?
It is not reflected. If your interest income is large, separate taxation may apply, so get tax advice if that applies to you.
Are the amounts I enter saved?
They are not saved. Refreshing returns it to its initial state.