Savings & Deposit Calculator
Monthly savings or lump-sum deposit — maturity interest and after-tax payout in one place. Standard Korean bank formula.
| # | Monthly | Principal cumul. | Interest cumul. (gross) |
|---|
How to Use
"Monthly savings (적금)" or "Lump-sum deposit (예금)". Most Korean banks use simple interest for savings; deposits sometimes offer compound interest.
Enter monthly amount (savings) or principal (deposit), term in months, and annual rate (%). Toggle 15.4% general tax or tax-free (youth savings, ISA, etc.).
Principal total, gross interest, tax, and net payout appear together. Savings mode shows a monthly accumulation table so you can estimate early-withdrawal payouts as well.
FAQ
How is Korean savings interest computed?
Korean banks use simple interest for regular savings: maturity interest = monthly deposit × annual rate × (n × (n+1)) / 2 / 12, where n is months. Each monthly deposit only earns interest for its remaining time to maturity.
Simple vs compound for deposits?
Simple: principal × rate × years. Compound: principal × (1 + rate/12)^months − principal. Difference is small for under 1 year but grows over 5+ years. Most 1-year Korean term deposits use simple; some 5+ year bond-type products offer compound.
What is the 15.4% general tax?
Korean interest income tax 14% + local tax 1.4% = 15.4% total, automatically withheld at maturity. Tax-incentive accounts (youth savings, parts of ISA, certain tax-free savings) are either tax-free or get a reduced 9.5% rate.
Savings vs deposit — which is better?
At the same rate and total amount, a lump-sum deposit earns roughly 2× the interest of monthly savings, because the full amount earns interest from day 1 while monthly deposits average ~6.5 months. Savings is better for building a habit and turning monthly cash into a lump sum.
Why the monthly accumulation table?
To estimate payout on early withdrawal. Note: banks apply a much lower "early-termination rate" (0.1–0.5%), so actual early payout is less than shown. Confirm the early-termination rate with your bank.
Is my input sent to a server?
No. All computation runs in your browser. Inputs are never sent over the network, never stored in localStorage or cookies.
