Calculate simple interest using principal, rate, and time. Find total interest earned and final amount for basic interest calculations. Everything runs locally in your browser — nothing is uploaded.
Calculate total price including sales tax. Enter the pre-tax amount and tax rate to see the exact tax amount and final total. Everything runs locally in your browser — nothing is uploaded.
Calculate monthly mortgage payments with amortization schedule. Enter loan amount, interest rate, and term to see total interest paid. Everything runs locally in your browser — nothing is uploaded.
Calculate monthly car loan payments, total interest, and total cost. Enter loan amount, rate, and term for a complete auto financing picture. Everything runs locally in your browser — nothing is uploaded.
Calculate heart rate training zones by age. Find your target heart rate ranges for different exercise intensity levels. Everything runs locally in your browser — nothing is uploaded.
Convert time between different time zones. Enter a time and your source/target time zones and see the converted result. Everything runs locally in your browser — nothing is uploaded.
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, months, and days. The calculator converts all time inputs to years for consistent calculation.
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.