Savings Calculator
Enter your monthly deposit, period and annual rate to get simple or monthly-compound interest and the after-tax payout in real time. All calculations run in your browser.
Enter the amount, period and rate to see the result.
How to use
- Enter the monthly deposit, period (months) and annual rate.
- Choose simple/monthly compound and the tax type.
- The after-tax payout, total principal, pre-tax interest and tax appear in real time.
Calculation basis and verification sources
Deposits are assumed at the start of each month. Simple interest is monthly deposit × (annual rate ÷ 12) × n(n+1) ÷ 2, while monthly compounding uses an annuity-due formula. The Korean ordinary-tax preset is 15.4%: 14% income tax plus local income tax equal to 10% of that tax.
Law checked: 2026-08-07. Tax exemption and reduced rates depend on product, enrollment date, and eligibility, so no universal preferential preset is offered. Enter the product's actual deposit timing and tax rate, and check its day-count, bonus rate, early-termination rate, and rounding rules.
Frequently asked questions
What is the difference between simple and monthly compound interest?
Simple interest accrues only on the principal, while monthly compound interest also accrues on the interest added each month. Most Korean installment savings products use simple interest.
How much is the interest income tax?
For ordinary taxable Korean deposits, the preset is 15.4%: 14% income tax plus local income tax equal to 10% of that tax. Exemption and reduced rates depend on the product and eligibility, so verify the product and enter its rate manually.
When are deposits assumed to be made?
Deposits are assumed at the start of each month (annuity due). Actual products may differ slightly depending on how they calculate interest.
Practical example and verification criteria
Savings Calculator: Before calculating, check whether amounts are before or after tax, whether a term is in days, months, or years, whether a rate is annual or monthly, and whether start and end dates are inclusive. Align body measurements and currency, length, and time units as well. On-screen defaults may be illustrative assumptions, so replace them with your own conditions.
Savings Calculator: For a quick check, start with 100,000 × 12 → 1,200,000 + interest as a small input whose result relationship you can verify directly. Confirm that the input summary, units, and options match your intent before applying the tool to real values or a copy of the source; this reduces setup mistakes.
Savings Calculator: Read the input summary and formula, then check reversible relationships such as principal plus interest, net amount plus tax, or start date plus term. Test values around rounding, zero, one, and date boundaries. Compare health, finance, tax, and administrative results with current official information for the applicable region and effective date.
Savings Calculator · Work record: For real work, record the input conditions, selected options, and result together. Do not assume the same state will remain after a refresh or device change. Preserve important results separately using copy, download, a screenshot, or another method the page supports, then reopen them in the target environment.
Savings Calculator · Error check: If an error or unexpected result appears, reduce the input, run again with default options, and then change one condition at a time. Recording error messages and boundary values helps distinguish format issues, unsupported cases, and browser resource limits, and prevents an empty result from being mistaken for success.
Savings Calculator · Scope of use: Check the page guidance for browser processing versus server lookup, storage location, and supported scope. Use sensitive source material or secrets only when strictly necessary. High-impact work such as legal, financial, or medical decisions or changes to an operational system requires current authoritative information and a separate verification process.
This result is an estimate for reference only and may differ from actual figures depending on applicable rules and individual circumstances. Confirm important decisions with the relevant authorities or a professional.