Before you sign up for a bank product, instantly see "how much will I actually get at maturity" and "how much do I need to repay each month" with a fully offline interest calculator. No account, no network, no permissions required.
💰 Deposit Calculator
Enter the principal, annual rate, and term, choose simple or compound interest, and instantly get pre-tax interest, tax withheld, and the after-tax payout. The tax rate defaults to 15.4% (Korea standard) but can be edited directly to match tax-free or reduced-tax products.
📈 Savings (Installment) Calculator
Enter the monthly deposit, annual rate, and term to see the maturity payout along with pre-tax and after-tax interest.
🏦 Loan Repayment Calculator
Enter the loan amount, annual rate, and term, choose a repayment method (equal principal & interest / equal principal / lump-sum), and get the monthly payment and total interest.
📊 Principal vs. Interest Visualization
See the ratio between principal and interest at a glance with a simple bar chart on the results screen.
🌏 Korean / English support
Pick your preferred language right in Settings.
🔒 Privacy-friendly
No sign-up or login needed. Amounts and rates you enter are stored only on your device and never sent to any server.
Deposits, savings, loans — let Simple Interest Calculator handle the math.
Calculate deposit, savings, and loan interest with after-tax amounts, offline