What does it calculate?
Choose one of six types. Installment (simple / compound) estimates maturity when you save the same amount every month. Deposit (simple / compound) is for a one-time lump sum. “Simple interest only” is principal × annual rate × years. “Loan (equal payment)” is the monthly payment on a standard amortizing loan. The principal field switches between monthly contribution, lump sum, or loan principal depending on the type.
Simple vs compound interest
Simple interest means you earn (or owe) interest once on the agreed principal for each period—interest does not earn more interest. Compound interest adds each period’s interest to the balance, so the next period’s interest is calculated on a larger amount. At the same annual rate, compound grows faster over time. Real banks use many variants (monthly vs annual compounding, tiered rates, tax, fees). There is no single answer to “which is usual”—it depends on the product. This page is a simplified educational split so you can pick a type without mixing formulas.
Notes
Real products may use different day-count rules, rounding, fees, insurance, prepayment penalties, or variable rates. This page is a rough educational estimate, not a quote from a lender. Numbers you enter stay in this browser and are not sent to a server.
How to use it
Pick a type first. The short hint under the dropdown explains what to enter. Installment savings use monthly payment, rate, and term in months; lump-sum deposits and loans use principal, rate, and months; “simple interest only” uses principal, rate, and years. Currency only changes labels—no FX conversion.
Related information
Mortgages and savings accounts differ by country and bank. APR, APY, compounding frequency, and taxes can all change the numbers you see on a real statement. For tax, legal, or investment decisions, consult a qualified professional.