Calculate simple interest using principal, rate, and time. Find total interest earned and final amount for basic interest calculations. Figures never leave your device — every calculation runs locally in your browser.
Calculate monthly mortgage payments with amortization schedule. Enter loan amount, interest rate, and term to see total interest paid. Figures never leave your device — every calculation runs locally in your browser.
Calculate monthly car loan payments, total interest, and total cost. Enter loan amount, rate, and term for a complete auto financing picture. Figures never leave your device — every calculation runs locally in your browser.
Calculate compound interest on a single principal. See how your money grows over time with different compounding frequencies. Figures never leave your device — every calculation runs locally in your browser.
Calculate customer churn rate by dividing customers lost by total customers. Monitor retention health for your subscription business. Numbers never leave your device — every calculation runs locally in your browser.
Calculate revenue growth rate by comparing current period revenue to previous period. Track your business growth over time. Numbers never leave your device — every calculation runs locally in your browser.
SI = P × R × T / 100, where P = principal, R = annual interest rate (%), T = time in years. Total amount = P + SI.
Simple interest is calculated only on the principal. Compound interest is calculated on principal plus accumulated interest. Simple interest produces lower returns over time.
Years only — the time field is a plain year count. Convert months or days to fractional years yourself before entering.
Short-term loans, car loans, some personal loans, and educational examples. Most mortgages and long-term investments use compound interest.
No. All calculations run locally in your browser. No financial data is transmitted.
$10,000 at 5% for 3 years gives Simple Interest $1,500.00, Total $11,500.00, and Annual interest $500.00 (principal × rate ÷ 100 × years). Try the $50k/8%/5yr preset: $20,000 interest on a $70,000 total.
Last updated October 2026