Interest Calculator

Calculate compound interest with annual/monthly contributions, begin/end timing, tax, and inflation.

Interest Calculator helps you project compound interest with annual and monthly contributions, tax, and inflation. Enter initial investment, annual contribution, monthly contribution, interest rate, and years, review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Interest calculator does Interest Calculator is built for money decisions — loans, savings, payments, and taxes. Project compound interest with annual and monthly contributions, tax, and inflation. You enter initial investment, annual contribution, monthly contribution, interest rate, and years, then Simple Calculators computes the result instantly. Rates, fees, and tax rules vary by lender and country, so treat results as planning numbers, not a contract. How the math works Annual and monthly contributions are combined into a monthly deposit stream. Interest may compound at the frequency you choose. An optional tax rate reduces the effective return; inflation adjusts ending purchasing power. The formula: FV = P × (1 + r ÷ n)^(n × t) + D × ((1 + r ÷ n)^(n × t) − 1) ÷ (r ÷ n). P is the starting amount, D is the deposit each compounding period, r is the yearly r…